JPH10285964A - Ultrasonic motor and rotor used for the motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the efficiency of a motor by synthesizing vertical vibration and torsional vibration, generated by converting vertical vibration, to generate elliptical vibration, and providing the rotor with a vibration converting means which converts vertical vibration into torsional vibration. SOLUTION: An upper and lower piezoelectric elements 4, 5 of a stator 8 are oppositely polarized. When one piezoelectric element 5 expands, the other piezoelectric element 4 also expands. When one piezoelectric element 5 shrinks, the other piezoelectric element 4 also shrinks. By forming slits 2a, torsional vibration is generated from the vertical vibration of the piezoelectric elements 4, 5, and further elliptic vibration is generated. When slits 12 are formed on a rotor 10, torsional vibration is generated in the rotor 10 itself as well. That is, when vertical vibration in the stator 8 is transferred to the rotor 10, torsional vibration is generated from the vertical vibration by the slits 12, and this torsional vibration is combined with the vertical vibration to generate elliptic vibration. Thus, the rotor 10 can be rotated at high speed by combining elliptic vibration in the stator 8 with elliptic vibration in the rotor 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic motor and a rotor used for the same, and more particularly to a standing wave type ultrasonic motor and a rotor used for the same.

[0002]

BACKGROUND OF THE INVENTION A standing wave type ultrasonic motor is shown in FIG.
6A and the torsional vibration shown in FIG. 6A are combined to generate an elliptical vibration in the stator to drive the rotor. FIG. 6A shows a stator.
The block 102 includes slits 102 a including piezoelectric elements 2 and 103 and piezoelectric elements 104 and 105. Also,
FIG. 6A is a diagram illustrating a waveform of a secondary resonance vibration in torsional vibration, and FIG. 6B is a diagram illustrating a waveform of a primary resonance vibration in a longitudinal vibration of the stator. The longitudinal vibration gives buoyancy to the rotor, and the torsional vibration gives a rotating force to the rotor.

[0003] Specifically, for example, Japanese Patent Application Laid-Open No. 61-496.
The bolt-fastened Langevin type ultrasonic motor disclosed in Japanese Patent Publication No. 70 and the like generates torsional vibration from longitudinal vibration by bolting, and combines the two vibrations to generate elliptical vibration.

Further, in order to efficiently generate an elliptical vibration, a technique for forming a slit in a stator is disclosed in Japanese Patent Laid-Open No. 7-1995.
No. 75353, and the like. This slit has the same configuration as the slit 102a shown in FIG.

However, in the conventional standing wave type ultrasonic motor, a desired rotational speed cannot be obtained in many cases because the amplitude of torsional vibration generated from longitudinal vibration is small.

An object of the present invention is to solve this problem, and an object of the present invention is to provide an ultrasonic motor capable of increasing the efficiency of a motor by generating torsional vibration in a rotor. An object of the present invention is to provide a rotor used for the above.

[0007]

Means for Solving the Problems To achieve the above object, an invention according to claim 1 is directed to an ultrasonic motor for rotating a rotor by an elliptical vibration generated in the stator by bringing the rotor into contact with the stator. The elliptical vibration is generated by synthesizing a longitudinal vibration and a torsional vibration generated by converting the longitudinal vibration, and the rotor has a vibration conversion unit for converting the longitudinal vibration into a torsional vibration. And

According to the present invention, a longitudinal vibration is generated in the stator, and a torsional vibration is generated from the longitudinal vibration. The longitudinal vibration and the torsional vibration are combined to generate an elliptical vibration. And
This elliptical vibration causes the rotor to rotate. Moreover, according to the present invention, the rotor itself generates torsional vibration by the vibration conversion means formed on the rotor. That is, the longitudinal vibration transmitted from the stator to the rotor is converted into torsional vibration by the vibration converting means, and torsional vibration is also generated in the rotor. The torsional vibration is combined with the longitudinal vibration to generate an elliptical vibration. In this manner, the combination of the elliptical vibration of the stator and the elliptical vibration of the rotor makes it possible to increase the rotation speed of the rotor and improve the motor efficiency.

As the vibration converting means, a slit (Claim 2) or a contact piece which contacts the stator (Claim 3).
Is mentioned.

[0010] In particular, it is preferable that the slit or the contact piece is inclined as in the invention described in claim 4 or 5.

According to a sixth aspect of the present invention, there is provided a rotor of an ultrasonic motor which rotates in contact with a stator which generates an elliptical vibration in which longitudinal vibration and torsional vibration generated by converting the longitudinal vibration are combined. And a vibration conversion means for converting longitudinal vibration into torsional vibration.

According to the rotor of the present invention, when the longitudinal vibration generated in the stator is transmitted, torsional vibration also occurs in the rotor itself by the vibration converting means. The torsional vibration is combined with the longitudinal vibration to generate an elliptical vibration. Then, the elliptical vibration of the rotor and the elliptical vibration of the stator are combined, so that the rotation speed of the rotor can be increased and the motor efficiency can be improved.

[0013] As the vibration converting means, a slit (Claim 7) or a contact piece which contacts the stator (Claim 8).
Is mentioned.

In particular, as in the ninth and tenth aspects of the present invention, the slit or the contact piece is preferably inclined.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the entire ultrasonic motor according to the embodiment of the present invention. This ultrasonic motor includes a rotor 10 and a stator 8.

The stator 8 includes first to third blocks 1 to 3.
3, having piezoelectric elements 4 and 5 and electrode plates 6 and 7. These are connected by bolts (not shown) provided inside.

The two electrode plates 6 and 7 apply a high-frequency AC voltage to the piezoelectric element 4 from a voltage applying device. In addition, the end face of the block 2 electrically connected to the piezoelectric element 5 from the electrode plate 6 via the block 1 via the connecting bolt (not shown) acts as an electrode plate. A high frequency AC voltage having a desired frequency is applied by the electrode plate 7.

Therefore, a common high frequency AC voltage is applied to the piezoelectric elements 4 and 5 from the block 2 or the electrode plate 6 by using the electrode plate 7 in common. That is,
A high-frequency AC voltage is applied to each of the piezoelectric elements 4 and 5 with a reverse polarity.

On the other hand, as shown in FIG. 1, the polarization directions of the piezoelectric elements 4 and 5 are upside down.

Then, since the polarization directions of the piezoelectric elements 4 and 5 are upside down and the polarity of the applied voltage is upside down, the corresponding polarities are the same. When one piezoelectric element 5 expands, the other piezoelectric element 4 also expands, and when one piezoelectric element 5 contracts, the other piezoelectric element 4 also contracts. Thereby, the amplitude value in the vertical direction (longitudinal direction of the unillustrated coupling bolt) of the entire stator 8 can be set large.

A plurality of slits 2 are formed on the peripheral surface of the block 2.
a is formed. By forming the slit 2a, torsional vibration can be generated from the longitudinal vibration of the piezoelectric elements 4, 5. The rotor 10 is rotated by elliptical vibration generated by combining longitudinal vibration and torsional vibration. Note that the rotation direction of the rotor 10 is determined by the frequency of the AC voltage applied to the piezoelectric elements 4 and 5 and the material and shape of the stator.

In this embodiment, a slit 12 is also formed in the rotor 10. More specifically, the rotor 10 is provided with a lining material 14 on the stator 8 side, and the surface 16 of the lining material 14 comes into contact with the driving surface 8 a of the stator 8. A slit 12 is formed on the peripheral surface of the rotor 10.

Here, the rotor 10 rotates counterclockwise in FIG. The slit 12 is inclined in the rotation direction of the rotor 10 (counterclockwise direction) with the stator 8 side as a starting point when viewed from the peripheral surface side of the rotor 10. Specifically, the inner wall surfaces 12a of the slits 12 facing each other
However, it is inclined in the rotation direction of the rotor 10 with the stator 8 side as a starting point.

By forming the slits 12 in this manner, torsional vibration also occurs in the rotor 10 itself. That is, when the longitudinal vibration of the stator 8 is transmitted to the rotor 10, the slit 12 generates torsional vibration from the longitudinal vibration. This torsional vibration generates elliptical vibration in combination with longitudinal vibration. Thus, the elliptical vibration of the stator 8 and the rotor 1
In combination with the elliptical vibration of 0, the rotor 10 can be rotated at high speed.

FIG. 2 is a diagram showing the relationship between the rotational speed and the torque. As shown in the figure, in the present embodiment, it was possible to obtain approximately four times the number of rotations as compared with the conventional example having no slit in the rotor.

The present invention is not limited to the above embodiment, and various modifications are possible. FIG. 3A to FIG. 4C are diagrams showing modified examples of the above embodiment. According to any of the modifications, the same effects as those of the rotor 10 of the above embodiment can be obtained.

As shown in FIG. 1, the rotor 20 shown in FIG. 3A has a slit 22 inclined in the rotational direction (counterclockwise) starting from the stator 8 (see FIG. 1). Is formed, and a lining material 24 is provided. Here, the slit 22 does not penetrate the surface 26 that contacts the stator 8 (see FIG. 1), and is formed only on the peripheral surface of the rotor 20.

3B, similarly to the rotor 10 shown in FIG. 1, the slits 32 inclined in the rotational direction (counterclockwise) starting from the stator 8 (see FIG. 1). Is formed, and a lining material 34 is provided. Here, the slit 32 is formed not only on the surface 36 in contact with the stator 8 (see FIG. 1), but also on the opposite surface 38.
Also penetrates. The slits 32 penetrating the upper and lower surfaces are easy to form.

The rotor 40 shown in FIG. 3C comprises a block 41 and a lining material 44. The block 41 includes the stator 8 (FIG. 1) as in the rotor 10 shown in FIG.
A slit 42 is formed which is inclined in the rotational direction (counterclockwise direction) starting from the reference) side. In addition, the slit 42 is formed only in the block 41, and is not formed in the lining material 44. That is, the slit 42
Does not penetrate the surface 46 that contacts the stator 8 (see FIG. 1). Therefore, since the slit 42 can be easily formed so as to penetrate one end face of the block 41, the rotor 40 can be obtained only by attaching the lining material 44 thereto.

According to the rotor 40, the slit 42
Although it does not penetrate through the surface 46 that contacts the stator 8 (see FIG. 1), it penetrates through the end face of the block 41 and can be formed by cutting.

The rotor 50 shown in FIG. 4A comprises two blocks 51 and 53 and a lining material 54. The block 53 has a slit 52 penetrating the upper and lower end surfaces, similarly to the rotor 30 shown in FIG. The slit 52 also has a shape inclined in the rotation direction of the rotor 50 (indicated by an arrow in the drawing). Then, the block 51 is attached to one end face of the block 53, and the lining material 54 is attached to the other end face, thereby forming the rotor 50.

According to the rotor 50, the slit 52
Although they do not penetrate the upper and lower end surfaces of the rotor 50 but penetrate the block 53, they can be easily formed by cutting.

The rotor 60 shown in FIG. 4B comprises a block 61 and a lining material 64, and a slit 62 is formed in the block 61. The shape of the slit 62 is different from the slit 42 of the rotor 40 shown in FIG. That is, in the slit 62, one inner wall surface 62b stands upright at a right angle to the rotation direction of the rotor 60 (indicated by an arrow in the figure), and the other inner wall surface 62a faces the stator 8 (see FIG. 1). , And is inclined in the rotation direction of the rotor 60.

According to the rotor 60, the slit 62 is formed in the block 61 by forging, sintering, die casting or the like.
Can be obtained, and a low-cost, high-rotation, high-output, high-efficiency ultrasonic motor can be obtained.

Next, the rotor 70 shown in FIG. 4 (C) is provided with a contact piece 72 on one end face of a block 71, and the contact piece 72 is provided on the surface on the side of the stator 8 (see FIG. 1). A lining material 74 is attached. The contact piece 72 comes into contact with the drive surface 8a of the stator 8 (see FIG. 1) via the lining material 74.

The contact piece 72 is inclined in the direction of rotation of the rotor 70 (indicated by an arrow in the figure) with the stator 8 as a starting point. Specifically, the contact piece 72 has a plate shape, and the plate surface 72a and the plate surface 72b on the opposite side
Each of them is inclined in the rotation direction of the rotor 70 with the stator 8 (see FIG. 1) as a starting point. In short, the plate surfaces 72a and 72b of the contact piece 72 are
Is inclined like the inner wall surface 12a.

Even with such a contact piece 72, the rotor 70 can generate torsional vibration. And a high-speed ultrasonic motor can be obtained.

Next, FIGS. 5A and 5B are views showing another modification of the present embodiment. A rotor 80 shown in FIG. 5A is provided with a lining material 84 and a slit 82. This slit 82
Is not inclined unlike the slit 12 of the rotor 10 shown in FIG. Even with the slit 82 having such a configuration, since torsional vibration occurs in the rotor 80, it is possible to obtain an ultrasonic motor with high rotation and high output and high efficiency.

A contact piece 92 is formed on the rotor 90 shown in FIG. This contact piece 92 is shown in FIG.
Unlike the contact piece 72 shown in FIG. Even with the contact piece 92 having such a configuration, since torsional vibration occurs in the rotor 92, it is possible to obtain an ultrasonic motor with high rotation and high output and high efficiency.

[0040]

[Brief description of the drawings]

FIG. 1 is a diagram showing an entire ultrasonic motor according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a rotation speed-torque characteristic;

FIGS. 3A to 3C are views showing a modification of the embodiment.

FIG. 4A to FIG. 4C are diagrams showing modified examples of the embodiment.

FIGS. 5A and 5B are diagrams showing a modification of the embodiment.

6A and 6B are diagrams showing waveforms of longitudinal vibration and torsional vibration generated in a stator.

[Explanation of symbols]

 8 Stator 10, 20, 30, 40, 50, 60, 70 Rotor 12, 22, 32, 42, 52, 62 Slit 72 Contact piece

Claims (10)

[Claims] 1. An ultrasonic motor for rotating a rotor by an elliptical vibration generated in the stator by bringing the rotor into contact with the stator, wherein the elliptical vibration includes a longitudinal vibration and a torsion generated by converting the longitudinal vibration. An ultrasonic motor, wherein vibrations are generated by combining vibrations, and the rotor has vibration conversion means for converting longitudinal vibrations into torsional vibrations. 2. The ultrasonic motor according to claim 1, wherein said vibration converting means is a slit. 3. The ultrasonic motor according to claim 1, wherein said vibration converting means is a contact piece that contacts said stator. 4. The ultrasonic motor according to claim 2, wherein the slit is inclined. 5. The ultrasonic motor according to claim 3, wherein the contact piece is inclined. 6. An ultrasonic motor rotor that rotates in contact with a stator that generates an elliptical vibration in which longitudinal vibration and torsional vibration generated by converting the longitudinal vibration are combined. A rotor having vibration converting means for converting the vibration into a vibration. 7. The rotor according to claim 6, wherein said vibration converting means is a slit. 8. The rotor according to claim 6, wherein the vibration conversion means is a contact piece that contacts the stator. 9. The rotor according to claim 7, wherein the slit is inclined. 10. The rotor according to claim 8, wherein the contact piece is inclined.