JPS6135175A - Piezoelectric motor - Google Patents

Abstract

PURPOSE:To obtain a piezoelectric motor which has a simple structure and inexpensive and small size by providing two freely rotating clutches around a rotational shaft, securing at one side with the free unit of a platelike piezoelectric unit for deflecting to vibrate and at the other side to the inner wall of a case. CONSTITUTION:Two freely rotting clutches 3, 4 are mounted around a rotational shaft 2 in the same direction. A platelike piezoelectric unit 7 which deflects to vibrate like a bimorph piezoelectric unit is rotatably supported at one end to a case 1 via a pin 8, and the free end through a coupling member 16 at the outer wheel of the first freely rotating clutch 3 to convert the deflecting vibration of the unit 7 into the rotary force of the clutch 3. Further, the outer wheel of the clutch 2 is secured directly to the inner wall of the case 1. Thus, when the unit 7 is deflected vibrate, the rotation operation of the prescribed direction can be performed at the shaft 1.

Description

[Detailed Description of the Invention] [Industrial Application] The present invention relates to an actuator that uses piezoelectricity to convert electrical energy into rotational motion. The present invention relates to a piezoelectric motor in which a rotating shaft is intermittently driven to rotate by a combination of two free-rotating clutches that prevent rotation in one direction and a piezoelectric plate that bends and vibrates.

[Prior Art] A rotary actuator that converts electrical energy into rotational torque using a piezoelectric body is conventionally known. The actuator of the second type is essentially a low-speed, high-torque type and does not require a reduction gear, so it is possible to construct a compact and lightweight drive system. Further, since the rotation angle of one step is small, there are advantages such as minute positioning is possible. Therefore, although not particularly limited, it is extremely effective as a rotary actuator for driving the joints of an industrial robot, for example.

A rotary piezoelectric actuator such as B is described in, for example, Japanese Patent Laid-Open No. 57-173384. The conventional technology combines a plurality of two types of laminated piezoelectric bodies, and fixes and separates the rotating shaft from the case by expanding and contracting the first laminated piezoelectric body, and expands and contracts the second laminated piezoelectric body. The rotary shaft is driven by alternately repeating the relative rotational movement of the rotary shaft with respect to the case.

[Problems to be Solved by the Invention] As mentioned above, the conventional rotary piezoelectric actuator of the type B requires a plurality of two types of laminated piezoelectric bodies to be assembled in the case, and has a large number of parts. The problem is that the structure is complicated and difficult to assemble. In addition, the external shape inevitably becomes a large-diameter disk or columnar shape, which may become an obstacle in downsizing devices that use it.

The purpose of the present invention is to solve the problems of the prior art, have an extremely simple structure, can be manufactured with a very small number of parts, and can be manufactured not only in the shape of a disk or cylinder but also in the shape of an elongated prismatic or round bar. Since you can freely design the external shape of the motor, even in places where there is no space to mount a normal rotary motor, it is possible to design the external shape of the motor to fit the available space and install it, especially in OA equipment. It is an object of the present invention to provide a piezoelectric motor with a new structure that is effective in cases where miniaturization is required, such as in portable devices and portable devices.

[Top Means for Solving the Problems] The present invention, which can achieve such objects, comprises a rotating shaft, first and second free-rotating clutches into which the rotating shaft is inserted and fixed; is rotatably supported with respect to the case, the other end is fixed to the outer ring of the first free-rotating clutch, and the plate-shaped piezoelectric body bends and vibrates; It is a piezoelectric motor whose outer ring is fixed to the inner wall of the case in the same direction as the free rotation clutch.

In case B, the plate-shaped piezoelectric body housed in the case may have a so-called bimorph structure in which a piezoelectric plate is attached to both sides of an elastic thin plate, or a so-called unimorph structure in which a piezoelectric plate is attached to one side of an elastic thin plate. It may also have a type structure. Note that in these piezoelectric motors, the number of plate-shaped piezoelectric bodies may be only one, or a plurality of plate-shaped piezoelectric bodies may be arranged at symmetrical positions with respect to the rotation axis.

[The first and second free-rotating clutches, in which the rotating shafts are inserted, have a bearing-like appearance, and their internal mechanisms allow the inner and outer rings to freely rotate in one direction, but not in the opposite direction. The structure is such that if you try to rotate it, it will lock and connect the two. Therefore, the rotating shaft fixed to the inner ring rotates irreversibly.

Here, as mentioned above, one end of the plate-shaped piezoelectric body is pivotally supported on the inner wall of the case, while the other end is fixed directly or indirectly to the first free-rotating clutch. The outer ring of the first free rotation clutch vibrates in the circumferential direction due to the bending vibration of the piezoelectric body. At this time, if the rotating shaft is locked by the first free-rotation clutch, the rotating shaft will also rotate at a constant angle.

Next, when the piezoelectric plate returns to its original shape, the outer ring of the first free rotation clutch also rotates in the opposite direction.

At this time, the rotating shaft is free from rotation of the outer ring of the first free rotation clutch. Furthermore, even if the rotating shaft attempts to rotate in the rotational direction of the outer ring of the first free-rotating clutch, it is locked by the second free-rotating clutch, so the rotating shaft remains at that position without rotating in the opposite direction. Next, the plate-shaped piezoelectric body is deflected and displaced again, so that the first
The outer ring of the free rotation clutch rotates, and the rotating shaft that is locked to it also rotates in the same direction. At this time, the rotating shaft is free from the outer ring of the second free-rotating clutch, so even though the outer ring of the second free-rotating clutch is fixed to the inner wall of the case, the rotating shaft can rotate freely. By repeating the following actions, the rotating shaft rotates in a fixed direction.

By reversing the mounting directions of the first and second free rotation clutches, the rotating shaft can be rotated in the opposite direction. Further, by changing the frequency of the voltage applied to the laminated piezoelectric body, it is possible to freely adjust the rotation speed.

[Example] Hereinafter, the present invention will be explained in more detail based on the drawings. Fig. 1 is a sectional view showing an embodiment of the piezoelectric motor according to the present invention, Fig. 2 is a front view with a part of the case removed, and Figs. 3 and 4 are explanations of its operation. Figure - is. The piezoelectric motor shown in this embodiment has an elongated columnar case 1
The external appearance is such that the rotating shaft 2 is inserted through the center.

This rotating shaft 2 has first and second free rotating clutches 3,
It is inserted into and fixed to the inner ring of 4, and both ends thereof are supported by bearings 5. The outer ring of the first free rotation clutch 3 is fixed to a cylindrical holding member 6.

In the second embodiment, two bimorph plate-shaped piezoelectric bodies 7 are used, and they are arranged at symmetrical positions with respect to the rotation axis 2. One end of the plate-shaped piezoelectric body 7 is pivotally supported on the inner wall of the case 1 by a pin 8, and the other end is fixed to the holding member 6.

Further, the outer ring of the second free-rotation clutch 4 is fitted into and fixed to a fixing member 9, and the fixing member 9 is fixed to the inner wall of the case 1.

Here, the first and second free-rotating clutches 3゜4 have an external structure similar to a kind of bearing as described above, and their internal mechanism allows the inner ring and outer ring to rotate freely in one direction but in the opposite direction. If you try to rotate it in that direction, it will lock and connect the two. Therefore, when used in bearings,
The rotating shaft will only rotate in one direction. Such first and second free-rotating clutches 3.4 are mounted in the same orientation. Therefore, the first free-rotating clutch 3
If a rotational force is applied in one direction to the outer ring of the second free-rotating clutch 4, and at that time the rotating shaft 2 is locked to it and tries to rotate together, the inner ring of the second free-rotating clutch 4 will be The rotating shaft 2 becomes free and can rotate. On the other hand, if the outer ring of the first free rotation clutch 3 is rotated in the opposite direction, it will be able to rotate freely in relation to the inner ring, but even if the rotating shaft 2 tries to rotate in that direction, The relationship between the inner ring and the outer ring of the free rotation clutch 4 locks the inner ring from rotating in the same direction, and as a result, the rotating shaft 2 cannot rotate in that direction. In this way, the rotating shaft 2 rotates in only one direction when the first free-rotating clutch 3 rotates and oscillates.

The plate-shaped piezoelectric body 7 bends and vibrates as shown in FIG. 3 by applying an alternating voltage to it.

In other words, when no voltage is applied to the piezoelectric plate 7,
As shown in FIG. 3A, the plate-shaped piezoelectric body 7 is in a straight state, but when a positive voltage is applied, it curves convexly, for example, toward the left in the drawing, as shown in FIG. 3B. Here, one end of the plate-like piezoelectric body 7 is rotatably attached to the inner wall of the case 1 by a pin 8, and the other end is fixedly connected to the first free rotation clutch 3 via the holding member 6, so that this deflection The deformation causes the first free rotation clutch 3 to rotate by an angle θ. The present invention drives the rotating shaft 2 by utilizing the rotation of the first free-rotation clutch 3 caused by the bending deformation of the plate-shaped piezoelectric body 7.

The operation of the piezoelectric morph configured as shown in B is as follows. When viewed from the direction of the white arrow in Figure 4 ζ, the rotation axis 2
This shows the operation when rotating counterclockwise. Here, the first free-rotating clutch 3 is installed in such a direction that the inner ring is locked when the outer ring is rotated counterclockwise, and the second free-rotating clutch 4 is installed so that the inner ring is locked when the outer ring is rotated counterclockwise. It is installed in the direction that will be in a free state with respect to the outer ring when it is applied. Furthermore, when no voltage is applied to the plate-shaped piezoelectric body 7, it is in a straight and flat state, and when a positive voltage is applied, the upper side is bent to convex toward the left in the drawing, and the lower side is deformed to convex to the right in the drawing. . Below A
-D and C correspond to the numbers in the drawings.

A: No voltage is applied to the piezoelectric plate 7 and it extends straight. This is the initial state.

B. A positive voltage is applied to the piezoelectric plate 7 to curve it convexly in a predetermined direction. Then, the outer ring of the first free rotation clutch 3 rotates counterclockwise.

At this time, since the inner ring of the first free rotation clutch 3 is locked, the rotating shaft 2 also attempts to rotate counterclockwise. Second
In the free rotation clutch 4, the inner ring is free to rotate counterclockwise relative to the fixed outer ring, so
As a result, the rotating shaft 2 rotates one step counterclockwise in response to the bending deformation of the piezoelectric plate 7.

C0 Next, the voltage application to the plate-shaped piezoelectric body 7 is canceled to return it to its original straight state. Then, the first free rotation clutch 3
The outer ring of rotates clockwise. The inner ring is in a free state with respect to the movement of B, and the clockwise rotation of the rotary shaft 2 is prevented by the second free rotation clutch 4, so the rotary shaft 2 does not move and remains in the first free state. Only the outer ring of rotary clutch 3 will rotate clockwise.

D. Apply a positive voltage to the piezoelectric plate 7 again to bend and deform it. The state is exactly the same as in B above, and the rotating shaft 2 further rotates one step counterclockwise. By repeating these operations, the rotating shaft 2 can be rotated counterclockwise one step at a time.

As is clear from the above explanation, the rotation shaft can be rotated clockwise or counterclockwise by changing the mounting direction of the first and second free-rotation clutches, and the laminated piezoelectric The rotation speed can be freely adjusted by changing the frequency of the applied voltage.

In particular, the structure shown in Example B can have an elongated appearance, so even in places where there is no space to mount a normal rotary motor, the motor can be designed and installed to fit the available space. is possible.

Although the preferred embodiments of the present invention are as described above, it is strongly believed that the present invention is not limited to such specific configurations, and various modifications are possible within the scope of the claims. Needless to say, it is. For example, in the above embodiment, two sets of plate-shaped piezoelectric bodies are provided, but in principle, it is also possible to use only one set, or in some cases, three or more sets of plate-shaped piezoelectric bodies may be arranged in parallel at symmetrical positions about the central axis. Both are possible. Further, during operation, an alternating voltage may be applied or a pulse voltage may be applied.

[Effects of the Invention] Since the present invention is a piezoelectric motor constructed as described above, it is a matter of course that it has all the advantages of piezoelectric rotary actuators in the prior art. Since it can be designed and manufactured to suit the available space even in places where it seems that there is no space to mount a rotation/type motor, it is possible to mount a motor, and in particular, it is possible to downsize OA equipment and portable equipment. It is extremely effective in some cases. Furthermore, since a free-rotation clutch is used, the mechanism is simplified and durability can be improved, and the number of parts can be reduced, which can produce excellent effects.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an embodiment of the piezoelectric motor according to the present invention, Fig. 2 is a full view of the piezoelectric motor with a part of its case removed, and Figs. 3 and 4 are explanatory diagrams of its operation. be. DESCRIPTION OF SYMBOLS 1... Case, 2... Rotating shaft, 3... First free rotation clutch, 4... Second free rotation clutch, 7... Plate-shaped piezoelectric body.

Claims (4)

[Claims] 1. a rotating shaft, first and second free rotating clutches into which the rotating shaft is inserted and fixed; one end rotatably supported with respect to the case and the other end fixed to an outer ring of the first free rotating clutch; The piezoelectric motor is composed of a plate-shaped piezoelectric body that flexibly vibrates, and the second free-rotation clutch has an outer ring fixed to the inner wall of the case in the same direction as the first free-rotation clutch. 2. 2. The piezoelectric motor according to claim 1, wherein the plate-like piezoelectric material is a bimorph piezoelectric material. 3. The piezoelectric motor according to claim 1, wherein the plate-like piezoelectric body is a unimorph type piezoelectric body. 4. Claim 1, wherein the plate-shaped piezoelectric body and the first free-rotation clutch are fixedly connected via a holding member.
The piezoelectric motor according to item 2 or 3.