JP2568835B2 - Ultrasonic drive - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic drive device that drives a driven body using an asymmetrical bolt-fastened Langevin-type piezoelectric vibrator having long and short metal blocks. .

2. Description of the Related Art The ultrasonic motor proposed at present has two sets of electrodes bonded to one side of a ring-shaped piezoelectric ceramic, and the electrodes are arranged such that the standing waves excited by the respective sets of electrodes are shifted by 90 ° in position. The two sets of oscillators are arranged and an AC electric field applied to the two sets of electrodes has a phase difference of 90 ° in time.

In the conventional ultrasonic motor configured as described above, two standing waves having phases shifted by 90 ° are applied to the peripheral surface of the ring-shaped piezoelectric ceramic by applying an AC electric field to each electrode group from two sets of oscillators. Then, a traveling wave in which the two standing waves are combined is generated. Therefore, when the ring-shaped moving body is placed on the comb-shaped vibrating body adhered on the ring-shaped piezoelectric ceramic and the contact is strengthened, the moving body is moved by the traveling wave.

Problems to be Solved by the Invention However, this conventional ultrasonic motor requires a plurality of electrodes and two sets of oscillators for applying an AC electric field to these electrodes, so that the configuration of the electrodes is complicated, The structure of the body is complicated, and there has been a problem that the cost is high.

Also, as shown in FIG. 12, a bolt 32 is passed through a bolt washer 31, and a piezoelectric vibrator 33 is placed on the washer 31.
The terminal plate 34, the piezoelectric vibrator 35, the terminal plate 36, and the aluminum disk 37 are placed thereon sequentially, and the bolt 32 is passed through each of the holes,
Screw 3 of bolt 31 into screw hole 38a of torsion connector 38 at the top end
Screw 1a is fixed. In addition, this torsion connector 38
Is provided with a groove 38b in the center portion of the lower surface, provided with arc-shaped projections 38c on both sides of the groove 38b, and a beam 38d at the upper end is arranged so as to have a desired angle with the groove 38b.

In the conventional ultrasonic driving device configured as described above, when the piezoelectric vibrators 33 and 35 are vibrated in the thickness direction, the disk of the torsion connector 38 vibrates like a butterfly wing, and the excitation frequency is increased. Is a connector
When approaching the resonance frequency of 38, elliptical vibration occurs in the beam 38d. Therefore, as shown in FIG. 13, the disc 39 is placed on the beam 38d above the torsion connector 38, and the lower end of the center shaft 4 is
2 and a spring 42 is provided between the upper end of the central shaft 40 and the bearing 41 to twist the disc 39 into strong contact with the connector 38. Rotated by elliptical vibration.

However, even in this conventional example, the aluminum disk 37
There is a problem that the configuration of the torsion connector 38 fixed with the bolt 31 on the top is complicated.

Means for Solving the Problems In order to solve the above problems, the present invention sandwiches a ring-shaped piezoelectric vibrator between a long metal block and a short metal block, and passes a bolt through a center hole of the piezoelectric vibrator. An asymmetric bolt-fastened Langevin-type piezoelectric vibrator in which the screws at both ends are fitted into the screw holes of the long and short metal blocks to integrally fix the long metal block, the piezoelectric vibrator and the short metal block. By applying a predetermined high-frequency voltage to the electrodes of the asymmetrical bolt-fastened Langevin type piezoelectric vibrator, the longitudinal vibration generated by the expansion and contraction of the piezoelectric body of the piezoelectric vibrator and the torsional vibration caused by the screw of the bolt are reduced. A circumferential traveling wave due to synthesis is generated on the end face and side face of the asymmetrical bolt fastening Langevin-type piezoelectric vibrator, and the asymmetric bolt fastening is performed. The end face or side face of the Langevin type piezoelectric vibrator is combined with a driven body.

According to the present invention, when a high-frequency electric signal is applied to the electrodes of the piezoelectric body of the asymmetrical bolt-fastened Langevin-type piezoelectric vibrator having long and short metal blocks with deformed side and short portions, the piezoelectric body vibrates in the thickness direction. I do. Here, since the piezoelectric body is strongly pressurized by bolts with metal cylinders on both sides, torsional vibrations are generated by the screws of the bolts due to the vibrations of the piezoelectric body, and the vertical vibration and the radial vibration are combined. Accordingly, a traveling wave in the circumferential direction is generated on the end face of the vibrator, and a traveling wave in the circumferential direction is generated on a part of the side face of the vibrator. In the case of the conventional symmetrical bolted Langevin-type piezoelectric vibrator, the metal cylinders on both sides of the piezoelectric body are symmetrical, so their torsional vibrations cancel each other out. In the case of a piezoelectric vibrator, torsional vibration and longitudinal vibration are effectively generated in a long metal block, and a strong circumferential traveling wave is generated on a part of an end face and a side face of the vibrator. Therefore, by combining the driven body with the end face and the side face of the vibrator, the driven body has less wear due to the traveling wave and can rotate smoothly.

Embodiment Before describing an embodiment of the present invention, the principle will be described. First, as shown in FIG. 1 (a), electrodes 3 and 4 are provided on both sides of ring-shaped piezoelectric elements 1 and 2 made of piezoelectric ceramic or the like, respectively. An asymmetric bolt-fastened Langevin-type piezoelectric vibrator 8 is formed by being clamped and fixed between the metal block 6 and the short metal block 7, and oscillators are provided to the input terminals 3 a and 4 a of the piezoelectric elements 1 and 2 of the piezoelectric vibrator 8. When an AC voltage was applied from No. 9 and the detector was applied to the surface of the metal cylinder 6 to detect a traveling wave, it was confirmed that a traveling wave was generated in the direction of the arrow as shown in FIG. Comparing the waveform of FIG. 2 with the sectional view of the piezoelectric vibrator 8 of FIG. 3, it was confirmed that the traveling wave was small at the screws 11a and 11b of the bolt 10.

This principle will be briefly described. First, the electrodes 3, 4 of the piezoelectric elements 1, 2 of the bolted Langevin type piezoelectric vibrator 8
When a high-frequency electric signal is applied to the piezoelectric element 1, the piezoelectric elements 1 and 2 vibrate in the thickness direction. Here, since the metal blocks 6 and 7 on both sides of the piezoelectric elements 1 and 2 are strongly pressurized by the bolts 10, when the torsional vibrations are generated by the screws 11a and 11b of the bolts, mainly the longitudinal vibrations and A circumferential traveling wave is generated at the end face of the piezoelectric vibrator 8 by combining radial vibrations,
Further, a traveling wave in the circumferential direction is generated on a part of the side surface of the piezoelectric vibrator 8. In the case of the conventional symmetrical bolted Langevin type piezoelectric element vibrator, the metal blocks on both sides of the piezoelectric element are symmetrical, so their torsional vibrations cancel each other out.
In the case of the asymmetrical bolted Langevin type piezoelectric vibrator 8 of the present invention, when the length of the long metal block 6 has a certain ratio to the diameter, torsional vibration and longitudinal vibration are effectively generated, A strong circumferential traveling wave is generated on the end face and a part of the side face of the piezoelectric vibrator 8.

The driven body can be driven by bringing the driven body into contact with the portion of the piezoelectric vibrator 8 that generates the traveling wave.

In the above description, the two piezoelectric elements 1 and 2 are sandwiched between metal blocks 6 and 7 having different lengths and fastened with bolts 10. A metal block 6 on one electrode via an insulator;
Similarly, a traveling wave is generated in the piezoelectric vibrator 8 sandwiched between the piezoelectric vibrators 7. Further, by using a plurality of piezoelectric vibrators, stronger traveling waves can be generated on the side surfaces and the end surfaces of the metal blocks 6 and 7.

FIG. 4 is a configuration diagram of an ultrasonic drive device using the piezoelectric vibrator of the present invention. The rotating shaft 12 is rotated by a bearing or the like on the end surface of the piezoelectric vibrator 8 having the long metal block 6 having a truncated cone. The freely supported disk 13 is pressed into contact with a spring or the like.

The disk 13 of the ultrasonic driving device thus configured can be rotated by the traveling wave generated on the end face of the piezoelectric vibrator 8 according to the above-described principle. Since this traveling wave is very strong, if the disk 13 has an appropriate weight, the piezoelectric vibrator 8 can be erected and the disk 13 can be placed on the end face without pressing with a spring. But you can rotate it.

This configuration can be used as an ultrasonic motor,
The rotation of the rotating shaft 12 of the disk 13 can be transmitted to another driving body via a gear, a pulley, or the like. In addition, disk 13
When the AC voltage is cut off, it stops immediately.
Can be used as a servomotor.

FIG. 5 is a configuration diagram of another driving device using the piezoelectric vibrator of the present invention. A rotating shaft 14 is provided on a part of a side surface of the piezoelectric vibrator 8 having a long metal block 6 having a truncated cone. A disk 16 which is rotatably supported by the like or the like, and whose end surface 15 is inclined obliquely in accordance with the inclination of the long metal block 6 having a truncated cone, is pressed into contact with a spring or the like.

This configuration can be used as an ultrasonic motor,
The rotation of the rotating shaft 14 of the disk 16 can be transmitted to another driving body via a gear, a pulley, or the like. In addition, the disk 16
When the AC voltage is cut off, it stops immediately.
Can be used as a servomotor.

FIG. 6 is a block diagram of an ultrasonic driving apparatus according to another embodiment of the present invention, in which a part of a side face of a piezoelectric vibrator 8 having a long metal block 6 having a truncated cone is slid by bearings 17 and 18. A freely supported and rod-shaped driven body 19 is combined with the side surface of the long metal block 6 by springs 20 and 21.

This configuration can be used as a linear motor that moves the bar in a straight line.

FIG. 7 is a configuration diagram of a piezoelectric vibrator according to another embodiment of the present invention. The metal block 22 of the piezoelectric vibrator 8 is composed of a cylindrical portion 22a and a truncated conical portion 22b.

Also in the piezoelectric vibrator 8 configured as described above, strong circumferential traveling waves are generated on the end face of the truncated cone portion 22b and the side surfaces of the cylindrical portion 22a and the truncated cone portion 22b.

FIG. 8 is a configuration diagram of a piezoelectric vibrator according to still another embodiment of the present invention. The metal block 23 of the piezoelectric vibrator 8 has a long cylindrical portion 23a and a short frustoconical portion 23b. .

Also in the piezoelectric vibrator 8 configured as described above, a strong circumferential traveling wave is generated on the end face and the side faces of the cylinder 23a and the cone 23b.

FIG. 9 is a diagram showing the configuration of a piezoelectric vibrator according to still another embodiment of the present invention. The metal block 24 of the piezoelectric vibrator 8 has a small-diameter portion 24a of a truncated cone portion in contact with the piezoelectric body 1, and The diameter portion 24b is released.

Also in the piezoelectric vibrator 8 thus configured, a strong circumferential traveling wave is generated on the end face of the large diameter portion 24b and the side face of the truncated cone.

FIG. 10 is a configuration diagram of a piezoelectric vibrator according to still another embodiment of the present invention. The metal block 25 of the piezoelectric vibrator 8 is composed of a cylindrical portion 25a and a truncated cone portion 25b, and a truncated cone portion 25b. Is integrated with the cylindrical portion 25a.

Also in the piezoelectric vibrator 8 configured as described above, strong circumferential traveling waves are generated on the end face of the truncated cone portion 25b and the side surfaces of the cylindrical portion 25a and the truncated cone portion 25b.

FIG. 11 is a configuration diagram of a piezoelectric vibrator according to still another embodiment of the present invention. The metal block 26 of the piezoelectric vibrator 8 has a protruding portion 26b formed on a part of a cylindrical portion 26a. The protruding portion 26b is formed at the portion where the traveling wave of FIG. 1 is generated. In FIG. 11 (a), the protruding portion 26b is formed at a portion close to the piezoelectric body 1, and FIG. 11 (b) In, the protruding portion 26b is formed in a portion near the end face.

Also in the piezoelectric vibrator 8 configured as described above, a strong circumferential traveling wave is generated on the side surface of the protruding portion 26b and the end surface of the cylindrical portion 26a.

The driven body can be driven by combining the side face and the end face of the piezoelectric vibrator 8 with the driven body.

Note that the piezoelectric vibrator 8 of the present invention is an asymmetric Langevin-type piezoelectric vibrator in which a vibrator is interposed between a long metal block and a short metal block and fastened with a bolt, and the long metal is, for example, a pyramid. It may be composed of a pedestal or a truncated pyramid and a prism, and a rotating wave is generated on the side surface and the end surface of the piezoelectric vibrator 8 regardless of the configuration of the longer metal. Therefore, by combining the piezoelectric vibrator 8 with a driven body such as a disk or a rod, the driven body can be driven by a traveling wave generated in the piezoelectric vibrator 8. Also, the piezoelectric vibrator 8
Is mounted on the driving body and brought into contact with the piezoelectric vibrator 8 rail or the like, the driving body can be driven without the necessity of mounting a rotating body on the driving body.

Effect of the Invention As is clear from the above description, in the present invention, since the piezoelectric body is strongly pressed by the bolts with the long and short metal blocks on both sides, the piezoelectric body is twisted to the metal block by the screws of the bolt due to the vibration of the piezoelectric body. Vibration occurs, and a circumferential traveling wave is generated on the end face and the side face of the piezoelectric vibrator by combining the longitudinal vibration and the radial vibration, so that the driven body has less wear and smoothness due to the traveling wave. When the piezoelectric vibrator is attached to the driving body, there is an advantage that the driving body can be driven by the rotational vibration generated in the piezoelectric vibrator.

[Brief description of the drawings]

FIG. 1 is a diagram showing a state in which a traveling wave generated in a piezoelectric vibrator of the present invention is generated, FIG. 2 is a diagram showing directions and magnitudes of the traveling wave generated in the piezoelectric vibrator by arrows, FIG. 3 is a cross-sectional view of a piezoelectric vibrator of the present invention, FIG. 4 is a schematic configuration diagram of an ultrasonic drive device of an embodiment of the present invention, and FIGS. 5 and 6 are diagrams of another embodiment of the present invention. FIG. 7 to FIG.
FIG. 11 is a configuration diagram of a piezoelectric vibrator according to still another embodiment of the present invention, FIG. 12 is an exploded perspective view of a stator of a conventional ultrasonic motor, and FIG. It is a partial section side view. 1, 2,... Piezoelectric body, 3, 4,... Electrode, 3a, 4a... Input terminal, 6, 22, 23, 24, 25, 26.
... Short metal block, 8 Piezoelectric vibrator.

Claims (6)

(57) [Claims] 1. A ring-shaped piezoelectric vibrator is sandwiched between a long metal block and a short metal block, and a bolt is passed through a center hole of the piezoelectric vibrator and screws at both ends are inserted into screw holes of the long metal block and the short metal block. The long metal block, the piezoelectric vibrator, and the short metal block are fitted together to form an asymmetrical bolted Langevin-type piezoelectric vibrator integrally fixed, and the electrodes of the asymmetrical bolted Langevin-type piezoelectric vibrator are formed. By applying a predetermined high-frequency voltage, the traveling wave in the circumferential direction resulting from the synthesis of the longitudinal vibration generated by the expansion and contraction of the piezoelectric body of the piezoelectric vibrator and the torsional vibration caused by the screw of the bolt is converted into the asymmetrical bolt-fastened Langevin type. It is generated on the end face and side face of the piezoelectric vibrator, and is driven with the end face or side face of the asymmetrical bolt-fastened Langevin type piezoelectric vibrator. Ultrasonic driving device characterized by comprising a combination of and. 2. An ultrasonic wave according to claim 1, wherein a third substance such as a wear-resistant substance or a vibration transmitting substance is interposed between said end face or side face and said driven body. Drive. 3. The ultrasonic driving device according to claim 1, wherein said long metal block is a truncated cone. 4. The ultrasonic driving device according to claim 1, wherein said long metal block is a combination of a truncated cone and a cylinder. 5. The ultrasonic drive device according to claim 1, wherein said long metal block has a configuration in which a part of a cylinder projects. 6. The ultrasonic driving apparatus according to claim 1, wherein said long metal block is a truncated pyramid.