JP3297211B2 - Ultrasonic motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a standing wave type ultrasonic motor which is driven to rotate by an elliptical vibration generated by a combination of a longitudinal vibration and a torsional vibration.

[0002]

2. Description of the Related Art Conventionally, a bolted Langevin type ultrasonic motor has been known, and for example, a cantilever torsional ultrasonic vibrator disclosed in Japanese Patent Application Laid-Open No. 61-49670 is known. The piezoelectric motor used and the ultrasonic motor disclosed in JP-A-63-217984 are known.

FIG. 11 shows an example of a conventional bolted Langevin type ultrasonic motor. In the figure,
The metal blocks 104 and 106 are fixed so as to tighten the piezoelectric elements 100 and 102 with bolts 108, thereby forming a stator unit 120 that generates elliptical vibration.

That is, the piezoelectric element 1 is
When a high-frequency AC voltage is applied to 00 and 102, longitudinal vibration is generated by vibration of the piezoelectric elements 100 and 102 in the thickness direction, and torsion vibration is generated by torsion of the bolt 108. Elliptical vibration is generated by combining the torsion vibration with the vibration.

A disk 112 is disposed on the end face of the block body 106, and the disk 112 is urged by the spring 114 to contact the end face of the block body 106, and a rotation provided at the center is provided. A shaft 116 is supported by a bearing 118.

[0006] Since the disc 112 is in contact with the end face of the block 106, the elliptical vibration generated on the end face of the block 106 is transmitted to the disc 112, and the elliptical vibration causes the disc 112 to rotate. . Further, the rotation output can be taken out from the rotation shaft 116.

In general, an object has a frequency inherent to the object. The natural frequency in longitudinal vibration and the natural frequency in transverse vibration differ from each other due to differences in longitudinal elastic modulus, transverse elastic modulus, and the like. Things. And
This leads to the fact that the resonance frequency in longitudinal vibration is different from the resonance frequency in torsional vibration.

For example, in the above-described conventional ultrasonic motor, the stator 120 is formed of aluminum and has a diameter of 35 mm and a length L of 90 mm (piezoelectric element 10).
And the length of 0, 102 are also converted to aluminum).
When calculating each of the secondary resonance frequencies f02,

(Equation 1) Further, when each of the primary resonance frequency f11, the secondary resonance frequency f12, and the tertiary resonance frequency f13 in the torsional vibration is calculated,

(Equation 2) Here, v0 and v1 are the propagation velocities of the vertical and horizontal vibrations of the metal block body 30 and the like, respectively.
Calculated as 100 m / s and 3000 m / s.

As described above, the resonance frequency has a different value between the longitudinal vibration and the torsional vibration. However, the longitudinal vibration and the torsional vibration that actually occur are both the same piezoelectric element 10.
Since they are generated by excitation by 0 and 102, they have the same frequency. For example, the primary resonance frequency of the longitudinal vibration (28 kHz)
When the piezoelectric elements 100 and 102 are vibrated in z), both the longitudinal vibration and the torsional vibration are vibrations of 28 kHz.

However, in this case, the amplitude of the longitudinal vibration is amplified by resonance, whereas the amplitude of the torsional vibration is not amplified. The reason is that the resonance does not occur because the frequency of the torsional vibration is away from the primary resonance frequency (17 kHz) or the secondary resonance frequency (34 kHz). Alternatively, conversely, when excited at the primary resonance frequency of torsional vibration,
No resonance occurs in longitudinal vibration.

Therefore, in order to amplify both the longitudinal vibration and the torsional vibration by resonance at the same frequency, it is necessary to select the secondary resonance frequency of the longitudinal vibration and the tertiary resonance frequency of the torsional vibration which are relatively similar. was there.

That is, the secondary resonance frequency of the longitudinal vibration is 56
and the third-order resonance frequency of the torsional vibration is 51 kHz.
z, which are relatively close to each other, select them, and vibrate at 53 kHz, which is close to any frequency,
Resonance occurs in both longitudinal vibration and torsional vibration,
The amplitude is amplified.

However, in order to generate a larger driving force, it is preferable to generate longitudinal vibration and torsional vibration at a low frequency. The reason is that the smaller the frequency, the larger the amplitude. In the example above,
Vibration at an even lower frequency produces a larger amplitude than vibration at 53 kHz.

Therefore, if the resonance in the longitudinal vibration and the torsional vibration can be generated by the vibration of the low frequency, the amplitude of the longitudinal vibration and the torsional vibration can be maximized, and a large driving force can be generated. Alternatively, an ultrasonic motor that can be driven efficiently by vibrations of various frequencies can be obtained if resonance can be generated by vibrations of any frequency even at a high frequency. Then, it is also possible to design the ultrasonic motor after determining the frequency of the AC power supply.

Therefore, a means for arbitrarily changing the resonance frequency of the longitudinal vibration or the resonance frequency of the torsional vibration has been demanded. If this becomes possible, resonance can be generated at an arbitrary frequency in both longitudinal vibration and torsional vibration.

The present invention has been made in view of this point, and has as its object to change the resonance frequency of longitudinal vibration or the resonance frequency of torsional vibration so that resonance can be generated at an arbitrary frequency. An object of the present invention is to provide an ultrasonic motor that can be driven efficiently.

[0017]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention has a rotor section and a stator section, and the stator section is formed by elliptical vibration generated by combining longitudinal vibration and torsional vibration. In the ultrasonic motor that rotationally drives the rotor section, the stator section includes a piezoelectric element that generates longitudinal vibration by a high-frequency AC voltage, an electrode that applies a high-frequency AC voltage to the piezoelectric element, and the piezoelectric element. And a plurality of block bodies to be tightened with a torsion vibration generating means for generating the torsional vibration by the longitudinal vibration, wherein the block body has a predetermined order resonance frequency in the longitudinal vibration and a predetermined order resonance frequency in the torsional vibration. And at least one of a concave portion, a groove, a hole, and a hollow portion is formed so as to reduce the difference.

Further, in the ultrasonic motor according to the present invention, the elliptical vibration is generated by combining a longitudinal vibration having a primary resonance frequency and a torsional vibration having a secondary resonance frequency.

[0019]

According to the present invention, torsional vibration is generated by the torsional vibration generating means based on the longitudinal vibration generated by the piezoelectric element. Therefore, both the longitudinal vibration and the torsional vibration have the same frequency.

Then, since the longitudinal vibration and the torsional vibration have different resonance frequencies, even if resonance occurs in one vibration, resonance does not always occur in the other vibration, and generally no resonance occurs. Often.

Therefore, when at least one of a concave portion, a groove, a hole, and a hollow portion was formed in the block body, it was experimentally revealed that resonance occurs in both longitudinal vibration and torsional vibration.

In particular, it has been found that, as in the present invention, the so-called longitudinal primary and torsional secondary vibrations can be combined to rotate the rotor section with large amplitude vibrations.

[0023]

Next, an embodiment of the present invention will be described in detail with reference to the drawings. The present invention is characterized in that a concave portion, a groove, a hole, or a hollow portion is formed in the block body, and this point will be described later with reference to FIG.

FIG. 1 is a view showing the overall structure of an ultrasonic motor to which the present invention is applied, and FIG. 2 is an exploded perspective view showing a detailed structure and an assembled state of a stator section 20.

As shown in these figures, this ultrasonic motor comprises a rotor section 10 which is driven to rotate in a fixed direction, and a stator section 20 which rotates this rotor section 10 by means of elliptical vibration generated on one end face 12. It is comprised including. Then, the end surface 12 becomes a rotor contact surface.

The rotor section 10 is provided at the end face 1 of the stator section 20.
2 includes a disk 14 which comes into contact with a constant pressure, and a rotary output shaft 16 attached to the center of rotation of the disk 14. Therefore, when the elliptical vibration occurs on the end face 12 of the stator section 20, the disk 14 of the rotor section 10 is driven to rotate around the rotation output shaft 16 in one direction. The disk 14 and the rotation output shaft 16 are integrally formed, and the rotation of the disk 14 causes the rotation of the rotation output shaft 16.

The stator section 20 includes piezoelectric elements 22 and 24 formed in a ring shape by using a piezoelectric material such as ceramics, for example, and electrodes arranged so as to contact both sides of one of the piezoelectric elements 24 over the entire surface. Plates 26, 28, and a first metal block 30, a second metal block 32, and a third metal block 30 arranged to sandwich the piezoelectric element 22, the electrode plate 26, the piezoelectric element 24, and the electrode plate 28 from both sides. And a connecting bolt 36 (see FIG. 2) for fastening and fixing the first metal block 30 and the third metal block 34 located at both ends.

A screw hole (not shown) is formed at the center of each of the first metal block 30 and the third metal block 34 so that the connecting bolt 36 is screwed therein. Also, the second metal block 3
A bolt insertion hole 32 a having an inner diameter substantially equal to the outer diameter of the coupling bolt 36 is formed at the center of the bolt 2.

Further, each of the piezoelectric element 22, the electrode plate 26, the piezoelectric element 24, and the electrode plate 28 is provided with a coupling bolt 36.
A bolt insertion hole 22a having an inner diameter larger than the outer diameter of
26a, 24a and 28a are formed. The inner diameters of the bolt insertion holes 22a, 26a, 24a, and 28a are set outside the insulating collar 44 inserted outside the coupling bolt 36 when the piezoelectric element 22, the electrode plate 26, the piezoelectric element 24, and the electrode plate 28 are assembled. It is formed so as to substantially match the diameter.

The one end surface 12 of the third metal block 34 serves as a rotor contact surface as described above.
The other end surface 13 is in contact with the second metal block 32, and a plurality of oblique slit grooves 38 are formed so that the end portions of the second end surface 13 coincide with each other. Therefore, the stator 2
After assembling the second metal block body 32 and the third metal block body
And a plurality of oblique slit grooves 38 are formed substantially in the vicinity of the central portion thereof.

As the piezoelectric elements 22 and 24, those used as electrodes during polarization, for example, those obtained by polishing and removing silver and nickel surfaces after completion of polarization are used.

The stator section 20 includes a third metal block body 34, a second metal block body 32, and a piezoelectric element 2.
2, an electrode plate 26, a piezoelectric element 24, an electrode plate 28, and a first metal block body 30 are connected and integrated to form an external connection terminal 40 from one electrode plate 26 to the other. The external connection terminals 42 project from the electrode plate 28, respectively.

The two external connection terminals 40 and 42 apply a high frequency AC voltage having a constant frequency to the piezoelectric element 24. Further, since the end face 33 of the second metal block 32 electrically connected to the piezoelectric element 22 from the external connection terminal 42 via the coupling bolt 36 functions as an electrode plate, the second metal block A high frequency AC voltage having a constant frequency is applied by the body 32 and the external connection terminal 40.

Accordingly, a common high frequency AC voltage is applied to the piezoelectric elements 22 and 24 from the upper second metal block body 32 or the lower electrode plate 28 by using the same electrode plate 26. That is, the piezoelectric elements 22, 2
4 is applied with a high-frequency AC voltage having a reverse polarity.

On the other hand, as shown in FIG. 2, the polarization directions of the piezoelectric elements 22 and 24 are upside down.

Then, since the polarization directions of the piezoelectric elements 22 and 24 are upside down and the polarity of the applied voltage is upside down, the corresponding polarities are the same. When one piezoelectric element 22 expands, the other piezoelectric element 24 also expands, and when one piezoelectric element 22 contracts, the other piezoelectric element also contracts. Accordingly, the amplitude value in the vertical direction (the longitudinal direction of the coupling bolt 36) of the entire stator portion 20 can be set to be large.

To assemble the stator portion 20, first, one end of a connecting bolt 36 is screwed and fixed to the first metal block body 30, and then the insulating collar 44 is inserted. Electrode plate 28, piezoelectric element 2
4, each of the electrode plate 26 and the piezoelectric element 22 is sequentially inserted. Next, the second metal block 32 is connected to the connecting bolt 36.
Finally, the third metal block body 34 is screwed into the other end of the connecting bolt 36, so that the other members are fastened and fixed by the first and third metal block bodies 30 and 34.

Here, since the connecting bolt 36 is used merely for tightening the first and third metal blocks 30, 34, it is not necessary to strictly control the pitch, the tightening load, and various dimensional accuracy. Manufacturing becomes easy.

Further, the ultrasonic motor of the present embodiment does not generate torsional vibration using the tightening by bolts, and any method of tightening each member may be used. Therefore, since a commonly used nut or simply crimping of the connecting rod may be used, the cost of parts can be reduced and the manufacturing process can be simplified.

In this embodiment, the connection and fixing
Since no adhesive is used to fix the laminated surface of each member, it is possible to prevent variations in the resonance frequency of each motor and a decrease in the Q value, thereby improving the performance and reliability of the ultrasonic motor. Can be.

FIG. 3 is a view showing details of the oblique slit groove 38 formed in the third metal block body 34 of the stator section 20. FIG. 4A shows a view of the third metal block body 34 from the side, and shows a plurality of oblique slit grooves 3.
8 shows a state in which 8 is arranged so as to partially contact the lower end surface of the third metal block body 34. Since these oblique slit grooves 38 can be formed by cutting from the lower side or the lateral direction of the third metal block body 34, the formation can be performed relatively easily. Although the second and third metal block bodies 32 and 34 are formed by one metal block body, and a blade is inserted in the vicinity of an intermediate portion between the second and third metal block bodies 32 and 34, an oblique slit groove 38 is formed. You may do so.

FIG. 4B is a view of the third metal block body 34 as viewed from above.
4 shows a state in which twelve oblique slit grooves 38 are formed.

FIG. 4 is a view for explaining the positions of the piezoelectric elements 22 and 24 and the oblique slit grooves 38 in the stator section 20. FIG. 2A shows the stator section 20, and FIG. 2B shows the waveform of the primary resonance vibration in the longitudinal vibration, and FIG. 2C shows the secondary resonance in the torsional vibration. The vibration waveform is shown.

As shown in FIG.
24 is provided at the center of the stator section 20 in the axial direction. By doing so, the longitudinal vibration (not shown) actually generated by the excitation of the piezoelectric elements 22 and 24 has a node located at the center of the stator section 20.

As shown in FIG. 3B, the waveform of the primary resonance vibration in the longitudinal vibration has a node located at the center. Therefore, when the piezoelectric elements 22 and 24 are provided at the positions described above, the primary resonance vibration can be generated.

Next, as can be seen from FIGS. 9A and 9C, the oblique slit groove 38 is formed at a position slightly shifted from the position of the node of the secondary resonance vibration in the torsional vibration. Further, in terms of the relationship with the longitudinal vibration, it is preferable that the longitudinal vibration is set at a position substantially between the antinode and the node.

As described above, by forming the diagonal slit groove 38 at a position slightly shifted from the position of the node of the secondary resonance vibration in the torsional vibration, the diagonal slit groove 38 expands and contracts in different directions about the center thereof. Will do. In addition, since the inclination direction of the oblique slit groove 38 is different from the vibration direction of the vertical vibration, when such expansion and contraction occurs, a phenomenon occurs in which the rotation is performed in a direction in which the center portion rotates as a rotation center within a certain angle range. . As a result, a vibration in the torsional direction is generated in the oblique slit groove 38 portion of the third metal block body 34, and this vibration is generated by the other metal block bodies 30, 32.
Therefore, torsional vibration occurs in the entire stator section 20. Accordingly, the longitudinal vibration directly generated by the piezoelectric elements 22 and 24 and the torsional vibration generated by the action of the oblique slit groove 38 are combined, and the rotor contact surface 12
An elliptical vibration in a certain direction occurs on the upper side, and the elliptical vibration drives the rotor unit 10 to rotate in one direction.

The direction of rotation of the rotor section 10 (see FIG. 1) can be reversed by reversing the direction of inclination of the oblique slit groove 38. Therefore, the rotation direction of the rotor unit 10 can be set only by the inclination direction of the oblique slit groove 38.

Thus, if two types of third metal block bodies 34 are prepared in which the inclined directions of the oblique slit grooves 38 are opposite to each other, the rotation direction of the motor is set to the opposite direction depending on which one is used. Therefore, the effect of reducing the manufacturing cost by sharing the parts becomes large. This is a clear difference in comparison with the case of the conventional bolted Langevin type motor in which both the connecting bolt and the two metal blocks had to be replaced.

In the ultrasonic motor of this embodiment, elliptical vibration also occurs on the end face of the stator opposite to the rotor contact face 12. That is, the lower end surface 46 shown in FIG.
Since an elliptical vibration is also generated, an ultrasonic motor that simultaneously rotates and drives two rotor units can be provided by using this end surface as a rotor contact surface.

Next, the concave portions, grooves, holes,
Alternatively, the hollow portion will be described. FIG. 5 is a longitudinal sectional view of the stator section 20. As shown in the figure, a recess 50 is formed in the metal block body 30 at a substantially central portion of the rotor contact surface 12. The concave portion 50 is formed in a substantially cylindrical shape, and the purpose of forming the concave portion 50 is as follows.
It is as follows.

As described in the section of “Problems to be Solved by the Related Art and the Invention”, the longitudinal vibration and the torsional vibration actually vibrated by the excitation of the piezoelectric element are vibrations of the same frequency, Are different in longitudinal vibration or torsional vibration. Therefore, if excitation is performed so that resonance occurs in either longitudinal vibration or torsional vibration, the other resonance does not occur.

The inventors of the present invention conducted various experiments in order to find a means for bringing the resonance frequencies of the longitudinal vibration and the torsional vibration closer to each other, and found that the block body had a concave portion, a groove, a hole, or a hollow portion. It was confirmed that forming a part was effective.

The experimental data at this time will be described with reference to FIG. First, two stator parts were prepared.
Each of these stator portions has a vertical length of 38 mm, a diameter of 20 mm, and slit grooves formed at six positions at an angle of 50 degrees. In addition, a concave portion is formed in each of the stator portions as shown in FIG.
In each case, the inner diameter was 14 mm.

However, one of the stator portions (Experiment NO.
The depth of the concave portion of 1) was 10 mm, and the inner bottom surface was arranged at the position of the node of the secondary resonance vibration of torsional vibration (see FIG. 4). Also, the other stator portion (Experiment No. 2)
The concave portion was set to have a depth of 5 mm, and the inner bottom surface was arranged at an intermediate position between the node and the antinode of the secondary resonance vibration of the torsional vibration (see FIG. 4).

Here, assuming a stator portion having the above dimensions and no concave portion formed, the primary resonance frequency of longitudinal vibration and the secondary resonance frequency of torsional vibration are theoretically calculated. : 65 kHz, the secondary resonance frequency of torsional vibration: 78 kHz. Therefore, when excitation is performed so that resonance occurs in one vibration, resonance does not occur in the other vibration.

However, the above-mentioned stator portion having a recess formed in the stator portion is moved by the piezoelectric elements 22 and 24 to 60 k.
The following results were obtained when the resonance frequency was measured by exciting at Hz.

Experiment NO. Primary resonance frequency of longitudinal vibration: 60 kHz Secondary resonance frequency of torsional vibration: 64 kHz 2 Primary resonance frequency of longitudinal vibration: 61 kHz Secondary resonance frequency of torsional vibration: 65 kHz From this experimental result, when a concave portion is formed in the stator section, the primary resonance frequency of longitudinal vibration and the secondary resonance frequency of torsional vibration approach each other. I understood that. So, conversely,
When a stator having such a recess is used, when excitation is performed at a frequency close to the primary resonance frequency of longitudinal vibration or the secondary resonance frequency of torsional vibration, resonance occurs in both longitudinal vibration and torsional vibration. Is led.

Then, even when excited at a low-order resonance frequency, that is, at a low frequency, resonance can be generated in both the longitudinal and torsional directions. Since a larger amplitude can be obtained by exciting at a lower frequency, a larger amplitude can be obtained after all. Thus,
An ultrasonic motor capable of producing a large driving force can be obtained.

The present invention is not limited to the embodiment described above, but may be modified as shown in FIGS. 7 and 9, the slit grooves are not shown.

For example, the stator section 20 shown in FIG.
May be as shown in FIG. That is, in FIG. 7, the stator portion 52 has a metal block body 54 and an attachment portion 56 with the other. Also, this stator portion 5
The recess 58 formed in FIG. 2 is formed shallower than the recess 50 in FIG. Since the depth required for the concave portion varies depending on the physical size of the stator portion, the excitation frequency, and the like, it is necessary to find the optimum depth while confirming the results by experiments.

Alternatively, the block body of the stator portion may be formed as shown in FIG. FIG. 7 is a longitudinal sectional view of a block body according to a modification of the embodiment. For example, a metal block body 60 shown in FIG. 5A has a truncated cone shape and is formed with a tapered recess 62. The metal block body 64 shown in FIG. 6B has a cylindrical shape and is formed with a concave portion 66 having a tapered shape that is gentler than the concave portion 62. The metal block body 64 shown in FIG. 68 also has a cylindrical shape and is formed with a concave portion 70 having a slightly tapered shape. Further, the metal block body 72 shown in FIG. 3D has a truncated conical shape, and is formed with a concave portion 74 that is not tapered.

Alternatively, a groove or a hollow portion may be formed instead of the concave portion. For example, the stator unit 7 shown in FIG.
6, a groove 80 is formed on the peripheral surface of the metal block body 78. Also, the stator portion 82 shown in FIG.
A concave portion 86 is formed on the end surface of the metal block 84, and a metal block 88 is attached to the concave portion 86 side. By doing so, a hollow portion is formed by the concave portion 86. Further, metal blocks 92 and 94 are attached to the stator portion 90 shown in FIG. 9C in an overlapping manner, and a concave portion 96 is formed on an end surface of the metal block body 94. A metal block 94 is attached to the end face. By doing so, a hollow portion is formed by the concave portion 96.

In any of the shapes shown in FIGS. 7 to 9, the longitudinal and torsional resonance frequencies are close to each other. Alternatively, a hole may be formed in addition to the concave portion, the groove, or the hollow portion.

In the above embodiment, the primary resonance frequency of the longitudinal vibration and the secondary resonance frequency of the torsional vibration are combined. However, the present invention is not limited to this, and the secondary resonance frequency of the longitudinal vibration and the torsional vibration are combined. A combination with a third-order resonance frequency, or a third-order resonance frequency of longitudinal vibration and a fifth-order resonance frequency of torsional vibration may be combined.

When the secondary resonance frequency of the longitudinal vibration is selected, the piezoelectric element is arranged at the position of the node of the waveform at the secondary resonance frequency, It is necessary to match the position of the node of the waveform at the secondary resonance frequency. By doing so, longitudinal vibration resonance can be generated.

Further, in the above embodiment, the torsional vibration is generated by the slit groove. However, the present invention is not limited to this, and the present invention is applied to a case where the torsional vibration is generated by the bolt 108 as shown in FIG. May be.

Alternatively, the present invention may be applied to a device that generates torsional vibration by making the piezoelectric direction of a piezoelectric element oblique.

For such a structure in which the piezoelectric direction of the piezoelectric element is inclined to generate torsional vibration, refer to Japanese Patent Application No. Hei.
No. 65617, which is shown in FIG.
That is, in the figure, the stator unit 220 includes two piezoelectric elements 222 and 224 polarized in an oblique direction, two electrode plates 226 and 228 for applying a high-frequency AC voltage having a constant frequency to them, and And first and second metal block bodies 230 and 232 arranged so as to sandwich them, and a coupling bolt 336 for tightening the metal block bodies. When the piezoelectric elements 222 and 224 that are polarized in an oblique direction vibrate, longitudinal vibration along the rotation axis 216 of the rotor unit 210 and torsional vibration along the rotation direction of the rotor unit 210 can be simultaneously generated. As a result, an elliptical vibration in which the longitudinal vibration and the torsional vibration are combined is generated on the rotor contact surface 212, and the rotor 210 can be driven to rotate.

[0070]

As described above, according to the present invention, resonance can be generated at an arbitrary frequency by changing the resonance frequency of the longitudinal vibration or the resonance frequency of the torsional vibration, and the drive can be performed efficiently.

Further, according to the present invention, it is possible to produce a large driving force due to a vibration having a large amplitude.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of an embodiment to which an ultrasonic motor according to the present invention is applied.

FIG. 2 is an exploded perspective view showing a detailed structure and an assembled state of a stator unit.

FIG. 3 is a view showing details of an oblique slit groove formed in a third metal block body of a stator portion.

FIG. 4 is a view for explaining positions of a piezoelectric element and oblique slit grooves.

FIG. 5 is a longitudinal sectional view of the stator section shown in FIG.

FIG. 6 is a view showing experimental conditions in an example.

FIG. 7 is a longitudinal sectional view showing a modification of the stator section shown in FIG.

FIG. 8 is a longitudinal sectional view showing a modified example of the concave portion shown in FIG.

FIG. 9 is a diagram showing another embodiment of the present invention.

FIG. 10 is a diagram showing another embodiment of the present invention.

FIG. 11 is a view showing an example of a conventional bolted Langevin type ultrasonic motor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Rotor part 20 Stator part 22, 24 Piezoelectric element 26, 28 Electrode plate (electrode) 30, 32, 34 Metal block body (block body) 36 Connection bolt 38 Diagonal slit groove 50 Depression

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Keisuke Honda 20 Oyama-cho, Oiwa-cho, Toyohashi-city, Aichi Prefecture Inside Honda Electronics Co., Ltd. (56) References JP-A-64-8877 (JP, A) JP-A-3-178579 (JP, A) JP-A-4-265673 (JP, A) JP-A-63-1988 236577 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02N 2/00

Claims (2)

(57) [Claims] 1. An elliptical vibration having a rotor portion and a stator portion, which is generated by combining longitudinal vibration and torsional vibration.
In the ultrasonic motor in which the stator unit drives the rotor unit to rotate, the stator unit includes a piezoelectric element that generates longitudinal vibration by a high-frequency AC voltage, an electrode that applies a high-frequency AC voltage to the piezoelectric element, and a piezoelectric element. A plurality of block bodies for clamping the element therebetween, and torsion vibration generating means for generating the torsional vibration by the longitudinal vibration, wherein the block body has a resonance frequency of a predetermined order in the longitudinal vibration and a predetermined order in the torsional vibration. as the resonant frequency, the difference in shrinking of the recess is formed, the recess, the inner bottom position or the sections of the torsional vibration
An ultrasonic motor, which is arranged at an intermediate position between a node of a torsional vibration and an antinode . 2. The ultrasonic motor according to claim 1, wherein said elliptical vibration is generated by combining longitudinal vibration having a primary resonance frequency and torsional vibration having a secondary resonance frequency. .