JPH0667229B2 - One-way rotation drive - Google Patents

Description

The present invention relates to a unidirectional rotation drive device driven by a standing wave, which is applicable to a rotary ultrasonic motor (vibration wave motor) and the like.

[Conventional technology]

It is known that ultrasonic vibration generated by applying an alternating voltage to an electrostrictive element or a piezoelectric element can be converted into rotational movement or linear movement, and ultrasonic waves that use the movement thus obtained as a driving force. Various motors have been proposed.

Since this ultrasonic motor does not require a winding coil, it has the advantages that it has a simple structure and can be downsized as compared with conventional electromagnetic motors, and it can obtain high torque even at low speed rotation. ing.

The representatives of this type of ultrasonic motor are as follows.

(1) A motor using a traveling wave that vibrates a rod-shaped vibrating body and moves in the length direction.

(2) A motor in which two types of standing waves having different phases in time and space are generated in a ring-shaped vibrating body, and these standing waves are combined into a traveling wave.

(3) A motor that combines vertical vibration and torsional vibration, or vertical vibration and lateral vibration of a vibrating element.

[Problems to be solved by the invention]

In the motor of (1), it is necessary to provide an absorber at the end of the rod-shaped vibrating body and cancel the reflection of the traveling wave at the end or provide an energy feedback system. However, even if an absorber is provided at the end of the vibrating body, the vibration absorbed by the absorber changes to heat, and the efficiency cannot be improved. Further, the structure becomes complicated when the energy feedback system is provided.

The motor of (2) requires special consideration, such as superimposing two types of standing waves, and has a complicated structure and is difficult to control efficiently.

The motor of (3) also had to synthesize two types of vibrations, and had a complicated structure and poor efficiency.

[Object of the Invention]

The present invention provides a one-way rotation drive device capable of efficiently converting a standing wave applied to a vibrating body into a rotational motion, based on a principle different from a method using a traveling wave and a vibration synthesis method that have been conventionally performed. The purpose is to get.

[Means for solving problems]

According to the conventional idea of traveling wave motors, a standing wave is a superposition of waves traveling in opposite directions, so if the strength of both waves is equal, move the object in a specific direction. I can't.

However, as a result of experiments, standing waves have movement abilities in different directions, and it is possible to move an object in a particular direction by selecting only the movement abilities in that particular direction. Do you get it.

That is, when a bending standing wave is excited in a vibrating body such as an elastic body, its abdomen vibrates in a direction perpendicular to the vibrating body,
The node vibrates in a direction parallel to the vibrating body, but the abdomen,
It is empirically derived that there are kinetic forces opposite to each other with the node as a boundary, and kinematic abilities in the same direction exist at an arbitrary point on one surface of the vibrating body and a point on the back side thereof.

Therefore, the present invention provides a position between a node and an antinode of a standing wave generated in an annular vibrating body having a length that is an integral multiple of the wavelength of the vibration generated by the vibration source, from the antinode of the standing wave to the node direction. An extractor such as a convex portion that selects the motion component is provided, and the motion component in a specific direction of the standing wave is extracted by this extractor, and the contact body such as the rotor contacting the extractor and the vibrating body are relatively moved in a specific direction. It is designed to rotate.

[Principle of Invention]

As described above, the inventor has found that the standing wave partially has motion abilities in different directions, and if only the motion abilities in the specific direction are selected, the object can rotate or move.
The experiment that supports it will be described.

As shown in Fig. 1, a plate-shaped elastic body (thickness 15 mm, width 10 mm, length
250mm brass rod) 1 is vibrated by a vibration source 2 such as a Langevin oscillator (excitation frequency 43.2KHz),
A bending standing wave was generated in the elastic body 1, the roller 3 was pressed against the elastic body 1, and the relationship between the rotation direction and the position was examined.

As a result, as shown in FIGS. 2A and 2B, A to H and A'to
It was found that the rotation direction changes alternately at the position H '.

On the other hand, the wavelength λ of the bending wave will be calculated from the formula λ ² = 4π ² (E / 12ρ) ^1/2 · b / ω. Here, E is Young's modulus, ρ is the density of the rod, b is the thickness of the rod, and ω is the angular frequency. Therefore, (E / ρ) ^1/2 = 3480 × 10 ³ (vertical vibration speed of the bar) b = 5 ω = 2π × 4.32 × 10 ⁴ , and thus λ = 26.9 [mm].

Comparing this value with FIG. 1, it can be seen that the central portion of the elastic body 1 has a pitch of approximately 13 mm, which is close to λ / 2.

From this, the position where the rotation direction of the roller 3 changes is considered to be the node or antinode of the standing wave, and can be described as follows.

The rotation direction of the roller 3 is opposite between the front and back of the elastic body 1, and the rotation is the same in the region of λ / 4 from the node to the antinode,
The rotation directions are opposite to each other in the adjacent areas.

Here, a qualitative consideration is given to the above.

If vibration is present as a traveling wave Uy = A · sin (ωt−kx) (k = 2π / λ) in the thickness direction on a plate with a thickness of 2e (e is a plate thickness of 1/2), the wave is a traveling direction component. With Ux = −e · Uy ′ = e · A · k · cos (ωt−kx), each part of the traveling wave makes an elliptic motion.

Now, assuming that a standing wave is excited in the plate, and the vibration in the thickness direction is Uy = Asinωt · sinkx ……, as in the case of a traveling wave, the equation is accompanied by vibration of the X-direction component, and Ux = −e・ Uy ′ =-e ・ A ・ k ・ sinωt ・ coskx ....

According to the equation, the standing wave of the plate is different from the standing wave of the string (e = 0), and it can be seen that the node of Uy = 0 vibrates in the X direction at −e · A · k · sinωt. Also, from Uy / Ux =-(1 / ek) tankx ..., it means that each part of the plate is performing linear vibration with inclination (-tankx) / (ek). (Fig. 3) Considering the vibration pattern of the standing wave of the plate based on the above consideration, it becomes as shown in Fig. 4.

Comparing FIG. 4 with the above experiment, it can be seen that the rotation direction and the vibration direction of the roller 3 correspond to each other.

Considering the case where a traveling wave is excited in an annular elastic body assuming the above results, the above results will be examined. When exciting a traveling wave in an annular elastic body, a sine wave standing wave with a phase shift of π / 2 is synthesized from a spatial position shift of λ / 4.

sin (ωt-θ) = sinωt · cosθ-cosωt · sinθ = sinωt · cosθ + sin (ωt + π / 2) · cos (θ + π / 2) Overlapping standing waves with wavelengths λ / 4 shifted means the third In the figure, the right half is overlapped with the left half, and the same kind of longitudinal vibration and transverse vibration are superposed on the node N and the antinode L. However, at that point, two vibrations that are not necessarily orthogonal are superimposed.

Since the two vibrations are out of phase with each other by π / 2 in time, it can be seen that the node N and the antinode L have the same elliptical motion with a phase difference of π, but other points also have the same elliptic motion as shown below. You can see that

X component at any point; -e-A-k-sin ωt-coskx-e-A-k-sin (ω
t + π / 2) ・ cos (kx + π / 2) = -e ・ A ・ k ・ sin (ωt-kx) Y component at an arbitrary point; Asinωt ・ sinkx + Asin (ωt + π / 2) ・ sin (kx + π)
/ 2) = Acos (ωt-kx) That is, even if an equation is assumed as a bending standing wave, the synthesis of traveling waves by two types of standing waves is explained, and the equation is considered to be close to the actual vibration. To be

Conventional ultrasonic motors, whether of the traveling wave type or the vibration synthesis type, have been devised so that the contact point with the movable body makes an elliptical motion.However, in the standing wave type motor described here, Is considered to drive the movable body by linear vibration as shown in FIG.

The reason why the movable body can be driven even by the linear vibration as shown in FIG. 3 is that the movable body cannot completely follow the vibration because the acceleration of ultrasonic vibration is extremely large. It also appears in the phenomenon of friction reduction due to vibration.

From the above, the standing wave has movement capabilities partially different in rotation direction, and it is possible to move the object in a specific direction by selecting only the specific direction.

[First Embodiment] A first embodiment of the present invention (an ultrasonic motor capable of rotating one rotor at a constant speed) will be described below with reference to the drawings.

As shown in FIGS. 5 and 6, the ultrasonic motor of this embodiment includes a contact body (for example, a rotor) 74 rotatable about an axis (not shown), a vibrating body (for example, an elastic body ring) 70. ,
A vibration source (for example, a piezoelectric ring) 71 and a high frequency power source 76 are provided.

The contact body 71 is a disc or ring formed of a synthetic resin such as acrylic or a metal plate, and is in pressure contact with the vibrating body 70.

The vibrating body 70 is made of metal such as brass or aluminum,
An extractor (for example, a convex portion such as a protrusion) 73 (width is an angle α) for selecting a specific moving direction of the bending standing wave,
As shown in FIG. 7, between the node N and the antinode L of the bending standing wave S (1 /
At a position of 4 wavelengths), a region for every odd multiple or even multiple of 1/4 wavelength (λ / 4), for example, an interval (in terms of angle) of 1/2 wavelength (λ / 2) of the standing wave to be excited. β) are provided at equal intervals.

That is, the standing wave S is λ at the portion of the antinode L and the node N per wavelength λ.
The first to fourth sections a1 to a4 are divided by / 4 lengths, and the extractor 73 is provided in the odd-numbered sections a1 and a3 or the even-numbered sections a2 and a4. Therefore, the interval P of each of the extractors 73 is equal to λ / 2.

The vibrating body 70 has a ring length that is an integral multiple of the wavelength λ of the standing wave S. Further, the width of the extractor 73 is set to be equal to or less than a quarter wavelength of the standing wave.

The vibration source 71 is attached to the vibrating body 70 by attaching piezoelectric ceramics polarized in opposite directions alternately at the same intervals as the extraction body 73. The pasting position is such that the node of the standing pasting is near the extract body 73.

In such a configuration, the device operates as follows.

When a sinusoidal voltage is applied to the vibration source 71 by the high frequency power supply 76 to cause bending vibration in the vibrating body 70, for example, when the ring is excited so that the ring length becomes a standing wave of 9 wavelengths, every half wavelength of the standing wave Node N of the standing wave in the vicinity of the extraction body 73 arranged at equal intervals in
Occurs. Therefore, the motion component of the standing wave in the specific direction is transmitted to the plurality of extraction bodies 73, and the contact body 74 rotates in one direction.

According to the embodiment described above, the bending standing wave S generated in the vibrating body 70 is divided by the λ / 4 length between the antinode L and the node N per wavelength λ, and the first to fourth sections are divided. Since a1 to a4 are set and the extractor 49 is provided in the odd-numbered sections a1, a3 or the even-numbered sections a2, a4, when the standing wave S is excited in the vibrating body 70, the extractor 73 causes the extractor 73 of FIG. It vibrates in the direction of the solid arrow.

Since this vibration includes a motion vector parallel to the surface of the vibrating body 70, the contact body 74 in contact with the extracting body 73 can be rotated.

That is, it is possible to select the motion component in the specific direction of the bending standing wave from the motion components generated in the opposite directions for each quarter wavelength.
The contact body 74 can be rotated in one direction. Therefore,
It is possible to realize a rotary ultrasonic motor with a standing wave having a simple structure.

When a bending traveling wave is excited in a ring-shaped elastic body,
In order to make the standing wave as small as possible, special consideration is required, such as superimposing two types of standing waves. However, this is not necessary in this ultrasonic motor that positively uses the standing wave.

Furthermore, since it is not necessary to generate and synthesize two types of ultrasonic waves as in the conventional case, an ultrasonic motor can be realized by using only one type of high frequency power supply 76.

[Second Embodiment] Next, a second embodiment of the present invention (an ultrasonic motor in which two rotors have different rotation speeds) will be described with reference to FIGS. 8 and 9.

In the vibrating body (for example, elastic body ring) 243 of this embodiment, the extraction bodies (for example, protrusions such as protrusions) 249 and 250 for selecting a specific motion direction of the bending standing wave are the nodes and antinodes of the bending standing wave. At intervals (between quarter wavelengths), areas a1 and a3 at odd multiples of quarter wavelength or areas a2 and a4 at even multiples of quarter wavelength, for example, an interval of half wavelength of the standing wave to be excited. Are provided at equal intervals.

The vibrating body 243 has a ring length that is an integral multiple of the wavelength of the standing wave. The widths of the extractors 249 and 250 are not more than a quarter wavelength of the standing wave and are different from the widths of the extractors 249 and 250.

Further, contact bodies (for example, rotors) 241 and 242 that come into contact with the extraction bodies 249 and 250, respectively, are provided on the concentric circles.

The vibration source is the same as that of the first embodiment.

Therefore, when bending vibration is generated in the vibrating body 243 and, for example, excitation is performed so that the ring length becomes a standing wave of 9 wavelengths, the extraction bodies 249 and 250 arranged at equal intervals for every 1/2 wavelength of the standing wave.
A node of a standing wave occurs near. At that time, extract 249,25
Since the width of 0 is different, the extraction amount of the unidirectional motion component is different between the extraction body 249 and the extraction body 250. Therefore, the contact body 241
The rotation speed can be different while rotating the contact body 242 and the contact body 242 in the same direction.

Third Embodiment Next, a third embodiment (an ultrasonic motor that rotates two rotors in opposite directions) will be described with reference to FIGS. 10 and 11.

This embodiment is a rotary motor that simultaneously rotates the contact bodies 114a, 114b, which are rotors, in opposite directions. The vibration source in this embodiment is the same as that in the first embodiment.

The vibrating body 110 of this motor includes the first extractor 113a in the inner row.
And the second extractors 113b in the outer row are provided coaxially. The extractor 113a in the inner row is positioned at the odd-numbered a1, a3 of the λ / 4 section of the standing wave caused by the vibration source, and the extractor 113b in the outer row is the even-numbered a2, a4 in the same λ / 4 section.
Position. By this, 1 attached to the vibrating body 110
By driving the two vibration sources to excite, it is possible to cause the two contact bodies 114a and 114b to simultaneously perform rotational movements in mutually opposite directions.

[Modification]

Although the three embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and the following modifications are possible, for example.

(1) In each of the above-described embodiments, the example in which the contact body rotates has been described, but the contact body may be fixed and the vibrating body may rotate. That is, it is sufficient that the vibrating body and the contact body rotate relative to each other.

(2) Although the convex portion is shown as the extractor, it may be a roller or a wave-shaped irregularity.

(3) In the vibration source of each of the above-described embodiments, piezoelectric elements such as piezoelectric ceramics are arranged in an annular shape, but an appropriate number of piezoelectric elements may be attached to the vibrating body.

(4) Although the Langevin oscillator and the piezoelectric ceramic are shown as the vibration source in each of the embodiments, a magnetostrictive oscillator or the like may be used. Further, the vibrating body may be vibrated by using a permanent magnet or an electromagnetic magnet.

(5) In each of the above-mentioned embodiments, the extract bodies are located in the even-numbered or odd-numbered quarter wavelength sections and are arranged at 1/2 wavelength intervals. However, it is not always necessary to arrange at intervals of ½ wavelength, and for example, as shown in FIG. 12, the interval P of the extractors 269 provided on the vibrating body 263 may be set for each wavelength λ. Further, the extract bodies 269 may not be provided at equal intervals except for problems such as efficiency. That is, irregular intervals may be used.

(6) As shown in FIG. 13, the extractor 279 on the surface of the vibrating body 273 is, in principle, preferably provided in a portion that does not include the node N and the antinode L in the quarter wavelength section of the standing wave. As shown by 279 ', a shape slightly protruding to the belly L (or node N) is also allowed. Of course, in this case, the protruding portion from the belly L or the node N becomes a loss.

(7) The extract 289 of FIG. 14 partially protrudes from the predetermined quarter wavelength section, but of course, this structure is included in the concept of the present invention. That is, in the extractor 289, the coupling portion C with the vibrating body 283 may be substantially 1/4 wavelength or less.
This structure may be effective because the contact area with the contact body that contacts the extract body 289 is increased and the frictional force is increased.

(8) In the second and third embodiments, the extraction body and the contact body are two.
Although provided in rows, it is also possible to provide three or more rows of extractors having different widths and positions and rotate one or more contact bodies in three or more speeds or in different directions.

(9) In each of the above embodiments, the ultrasonic motor is shown as the one-way rotation driving device.
It can also be applied to electronic products that use magnetic recording media such as tape recorders and floppy disk drives, and precision positioning devices such as industrial robots and machine tools.

Further, in each of the above embodiments, the ultrasonic motor provided with the rotor as the contact body is shown, but as the one-way rotation device, the contact body may not necessarily be provided, and the paper, the card, or the object that needs to be rotated. It is also possible to bring the extract into contact with, for example, to rotate.

Therefore, in this case, the paper or the card corresponds to the contact body.
Therefore, it can be applied to a paper feeding device, a card feeding device, and the like.

〔The invention's effect〕

The present invention relates to a vibration source that generates a vibration of a specific frequency, an annular vibration body that is excited by the vibration source and has a length that is an integral multiple of the wavelength of the vibration generated by the vibration source, and that is generated in this vibration body. The contact body is provided between the node and the antinode of the standing wave in contact with the vibrating body and the contact body, and selects the motion component in the nodal direction from the antinode of the standing wave generated in the vibrating body. A unidirectional rotation drive device for rotating the contact body in one direction relative to the vibrating body, wherein the extracting body is provided in a plurality of rows with respect to the vibrating body. The contact body is provided for each row with respect to the plurality of rows of extractors, the extractor is provided at an arbitrary position for each row, and the width in the moving direction of the vibrating body side base is arbitrarily provided for each row. Since it is set, it is possible to rotate multiple contact bodies in one direction. Rutotomoni, it is possible to set the moving speed and the driving force for each contact member.

[Brief description of drawings]

1 to 4 are views for explaining the principle of the present invention, and FIGS. 1 and 2 (A) and (B) show the rotation direction of the roller when the elastic body is excited by a standing wave. FIG. 3 and FIG. 4 are explanatory diagrams of the positional relationship, and are waveform charts showing the vibration pattern of standing waves. 5 to 7 are views showing the first embodiment of the present invention. 8 and 9 are diagrams showing a second embodiment of the present invention. 10 and 11 are views showing a third embodiment of the present invention. 12 to 14 are views showing modified examples of the present invention. 70 …… Vibrator, 71 …… Vibration source, 73 …… Extractor, 74 …… Contact body, 76 …… High frequency power supply, 110 …… Vibrator, 113a, 113b…
… Extracted bodies, 114a, 114b …… Contact bodies, 241,242 …… Contact bodies,
243 …… Vibrator, 249,250 …… Extractor

Claims (1)

[Claims] 1. A vibration source that generates vibration of a specific frequency, an annular vibration body that is excited by the vibration source and has a length that is an integral multiple of the wavelength of the vibration generated by the vibration source, and the vibration body. The standing wave generated is provided between the node and the antinode in contact with the vibrating body and the contact body, and the contact component is selected by selecting a motion component in the nodal direction from the antinode of the standing wave generated in the vibrating body. A unidirectional rotation drive device that has an extractor that is transmitted to a body and that rotates the contact body in one direction relative to the vibrating body, wherein the extractor is provided in a plurality of rows for the vibrating body. , The contact body is provided for each row with respect to the plurality of rows of extractors, the extractor is provided at an arbitrary position for each row, and the width in the moving direction of the vibrating body side base is arbitrary for each row. The one-way rotation drive device is set to.