JP2568834B2 - Ultrasonic drive - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic driving apparatus that drives a driven body using a cylindrical or prismatic asymmetrical bolt-fastened Langevin-type piezoelectric vibrator. .

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 having a 90 ° phase difference with respect to time in the alternating electric field applied to these two sets of electrodes are connected.

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. 9, a bolt 32 is passed through a bolt washer 31, a piezoelectric vibrator 33 is placed on the washer 31, and a terminal plate 34, a piezoelectric vibrator 35, a terminal plate 36, An aluminum disk 37 is placed, and a bolt 32 is passed through each of the holes, and a screw 31a of the bolt 31 is inserted into a screw hole 38a of the torsion connector 38 at the uppermost end.
Is fixed by screwing. In addition, this torsion connector 38 is provided with a groove 38b in the center part of the lower surface, provided with an arc-shaped projection 38c on both sides of the groove 38b, and furthermore, the beam 38d at the upper end has a desired angle with the groove 38b. Are located.

In the conventional ultrasonic driving device configured as described above, when the piezoelectric vibrators 33 and 35 vibrate in the thickness direction, the torsional
The 38 disks vibrate like butterfly wings and the excitation frequency is
When the resonance frequency approaches the resonance frequency, elliptical vibration occurs in the beam 38d. Therefore, as shown in FIG. 10, the disc 39 is placed on the beam 38d above the torsion connector 38, and the lower end of the central shaft 40 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 The present invention, in order to solve the above problems, a ring-shaped piezoelectric element is sandwiched between a long metal cylinder or prism and a short metal cylinder or prism, and the center of the ring-shaped piezoelectric element is An asymmetrical bolt-tightened Langevin-type piezoelectric vibrator in which the long metal cylinder or prism and the short metal cylinder or prism are fixed by bolts passing through holes, and a high-frequency electric signal is applied to the electrode of the piezoelectric element. By doing so, a circumferential traveling wave is generated at the end or side of the Langevin type piezoelectric vibrator by combining the longitudinal vibration caused by expansion and contraction in the thickness direction of the piezoelectric element and the torsional vibration caused by the screw of the bolt. And a driven body is combined with the end or the side.

According to the present invention, when a high-frequency electric signal is applied to the electrode of the piezoelectric element of the bolted Langevin type piezoelectric vibrator,
The piezoelectric element expands and contracts strongly. Since the piezoelectric body is strongly pressurized by bolts with metal cylinders on both sides, torsion vibration is generated by the screws of the bolts, and traveling waves in the circumferential direction are generated by combining longitudinal vibration and radial vibration. 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 a conventional symmetrical bolted Langevin-type piezoelectric vibrator, the metal cylinders on both sides of the piezoelectric element are symmetrical, so that their torsional vibrations cancel each other out. In the case of a piezoelectric vibrator, when the length of the longer metal cylinder has a certain ratio to the diameter, torsional vibration and longitudinal vibration are generated effectively, and one end face and side face of the vibrator are generated. A strong circumferential traveling wave is generated in the portion, and the driven body has less wear and can smoothly rotate due to the traveling wave.

Embodiment Before describing an embodiment of the present invention, the principle will be described. First, as shown in FIG. 1 (a), electrodes 3, 4, and 5 are provided on both sides of ring-shaped piezoelectric elements 1 and 2 made of piezoelectric ceramic or the like, respectively, and these piezoelectric elements 1 and 2 are made of long metal. An asymmetric bolt-fastened Langevin-type piezoelectric vibrator 8 is formed by sandwiching and fixing the cylindrical vibrator 6 and a short metal cylindrical body 7, and the input terminals 3 a and 4 a of the piezoelectric elements 1 and 2 of the piezoelectric vibrator 8. When an AC voltage is applied from the oscillator 9 to the detector and the detector is applied to the surface of the metal cylinder 6 to detect a traveling wave,
As shown in FIG. 2, it was confirmed that a traveling wave was generated in the direction of the arrow. 2 and the sectional view of the piezoelectric vibrator 8 shown in FIG. 3, the screws 11a, 1
It was confirmed that the traveling wave was small in the portion of 1b.

To explain this principle in brief, when a high-frequency electric signal is applied to the electrodes 3 and 4 of the piezoelectric elements 1 and 2 of the bolted Langevin type piezoelectric vibrator 8, the piezoelectric elements 1 and 2 expand and contract strongly. The piezoelectric elements 1 and 2 are made of metal cylinders 6 and 7 on both sides.
Is strongly pressurized by the bolt 10, torsion vibration is generated by the screws 11 a and 11 b of the bolt, and a traveling wave in the circumferential direction is generated by combining the vertical vibration and the radial vibration. And a circumferential traveling wave 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 cylinders on both sides of the piezoelectric element are symmetrical, so their torsional vibrations cancel each other out. In the case of the piezoelectric element vibrator 8, when the length of the longer metal cylinder 6 has a certain ratio to the diameter, torsional vibration and longitudinal vibration are generated effectively, A strong circumferential traveling wave is generated on a part of the end face and the side face.

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 cylinders 6 and 7 having different lengths of metal, and
However, as shown in FIG. 4, one of the electrodes 3 and 4 of one piezoelectric element 1 (electrode 3 in the figure)
Similarly, a traveling wave is also generated in the piezoelectric vibrator 8 sandwiched between the metal cylinders 6 and 7 with the insulator 15 interposed therebetween. 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 cylinders 6 and 7.

FIG. 5 is a configuration diagram of a drive device using the ultrasonic vibrator of the present invention, in which a disk 17 having a rotating shaft 17a supported by a bearing 16 is pressed against an end face of a piezoelectric vibrator 8 by a spring 18. It is.

The disk 17 of the 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 17 has an appropriate weight, the piezoelectric vibrator 8 is erected without placing the disk 18 in pressure contact with the spring 18 and the disk 17 is placed on its end face. You can rotate it alone.

This configuration can be used as an ultrasonic motor,
The rotation of the rotation shaft 17a of the disk 17 can be transmitted to another driving body via a gear, a pulley, or the like. Further, when the disk 17 is pressed against the spring 18, the AC voltage is cut off immediately when the disk 17 is pressed, so that the disk 17 can be used as a servomotor.

FIG. 6 is a configuration diagram of another driving device using the ultrasonic vibrator of the present invention. Two rotating disks 19 and 20 are fixed to a rotating shaft 21, and the rotating shaft 21 is fixed to bearings 22 and 23. Rotatably supported,
Further, by pressing these bearings 22 and 23 by springs 24 and 25, the disk 19 or 20 is pressed against the side surface of the metal cylinder 6 of the piezoelectric vibrator 8. A groove 26 is formed in the dead zone portion of the metal cylinder 6.

In this configuration, the piezoelectric vibrator 8 or the rotating shaft 21 is moved to press the disk 19 against the side surface of the metal cylinder 6, and the disk 20 is moved.
Is positioned above the groove 26, and the traveling wave of the piezoelectric vibrator 8 moves as shown by the arrow A, the disk 19 rotates as shown by the arrow A '. Further, the piezoelectric vibrator 8 or the rotating shaft 21 is moved so that the disk 20 is brought into contact with the end of the metal cylinder 6 of the piezoelectric vibrator 8, and the disk 19 is inserted into the groove 26 provided in the dead zone. When the traveling wave of the piezoelectric vibrator 8 rotates as shown by the arrow B, the disk 21 can be reversed. Accordingly, this configuration can be used as a forward / reverse motor. By tilting the vicinity of the groove 26 obliquely, when the piezoelectric vibrator 8 or the rotating shaft 21 is moved,
The disks 19 and 20 and the metal column 6 of the piezoelectric vibrator 8 can be smoothly moved in and out of contact with each other.

FIG. 7 is a configuration diagram of a driving device according to still another embodiment of the present invention. Belts 27 and 28 are hung on a portion of the side surface of the metal cylindrical body 6 of the piezoelectric vibrator 8 where traveling waves are generated. These belts 27 and 28 are respectively hung on pulleys 31 and 32 fixed to rotating shafts 29 and 30, respectively. The rotating shafts 29 and 30 are separately supported by bearings 34, and the rotating directions may be reversed.However, the rotating shafts 29 and 30 are directly connected, a switching device is provided at the bearing 33, and a pulley 31 is provided. , 32, the pulleys 32, 33 and the rotating shafts 30, 31 may be connected or disconnected, respectively.

With this configuration, it is possible to rotate the rotating shafts 29 and 30 separately or to rotate the rotating shafts 29 and 30 forward and backward.

FIG. 8 is a block diagram of a driving device according to still another embodiment of the present invention, in which a portion of a fixed piezoelectric vibrator 8 where a traveling wave is generated is linearly moved by bearings 34 and 35. The rod 36 supported by the spring is pressed by a spring 37.

In the driving device of the present embodiment configured as described above, the rod 36 slides by pressing the rod 36 against the portion of the side surface of the drive block of the piezoelectric vibrator 8 where the traveling wave is generated. , Can be used as a linear motor. The moving direction of the rod 36 can be driven left and right in FIG. 8 by bringing the rods 36 into contact with each other with the dead zone of the drive block of the piezoelectric vibrator 8 as a boundary as described above. .

In the above embodiment, the piezoelectric vibrator 8 has a cylindrical shape, but may have a large diameter at the end face portion of the metal cylinder 6, or may have a polygonal cylindrical shape. Further, in the above-described embodiment, the driving body is brought into contact with the side surface or the end surface of the metal cylindrical body 6 of the piezoelectric vibrator 8, but the piezoelectric vibrator 8 is fixed to the moving body, and rails, roads, etc. If the mobile body is brought into pressure contact with the vehicle under its own weight, it can be configured as a self-propelled vehicle. Further, in the description of the above embodiment, an example in which a metal is used as the metal cylinder 6 has been described, but a synthetic resin can also be used. Further, in the embodiment of FIG. 6, the discs 19 and 20 are used, but rollers may be used.

Advantageous Effects of the Invention As is apparent from the above description, in the present invention, since the piezoelectric element is strongly pressed by the bolts on the metal cylinders on both sides, torsional vibration occurs due to the screw of the bolt due to the vibration of the piezoelectric element. At the same time, a traveling wave in the circumferential direction is generated on the end face of the piezoelectric vibrator by combining the longitudinal vibration and the radial vibration, and a traveling wave in the circumferential direction is generated on a part of the side surface of the piezoelectric vibrator. Also, when the length of the longer metal cylinder has a certain ratio to the diameter, torsional vibration and longitudinal vibration are generated effectively, and a strong circle is formed on the end face and a part of the side face of the piezoelectric vibrator. A traveling wave in the circumferential direction is generated, and the traveling wave has an advantage that the driven body has less wear and can rotate smoothly.

[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 sectional view of a piezoelectric vibrator of the present invention, FIG. 4 is a side view of a piezoelectric vibrator of another embodiment of the present invention, and FIG. 5 utilizes the piezoelectric vibrator of the present invention. FIG. 6 is a diagram showing a configuration for rotating a disk, FIG. 6 is a diagram showing a configuration for rotating the rotation axis forward and reverse by two disks using the piezoelectric vibrator of the present invention, and FIG. FIG. 8 is a diagram showing a configuration in which a rotation axis is rotated forward and reverse by a belt using a piezoelectric vibrator, FIG. 8 is a diagram showing a configuration in which a rod is driven using a piezoelectric vibrator of the present invention, FIG. 10 and FIG. 10 are configuration diagrams of a conventional ultrasonic drive device. 1, 2, a piezoelectric body, 3, 4, 5, an electrode, 3a, 4a, an input terminal, 6, 7, a metal cylindrical body, 8 a piezoelectric vibrator.

Claims (2)

(57) [Claims] 1. A ring-shaped piezoelectric element is sandwiched between a long metal cylinder or prism and a short metal cylinder or prism, and the long metal cylinder or prism and the short metal are clamped by a bolt passing through a center hole of the ring-shaped piezoelectric element. An asymmetrical bolt-tightened Langevin-type piezoelectric vibrator to which a cylindrical or prismatic column is fixed, wherein a longitudinal vibration caused by expansion and contraction of the piezoelectric element in a thickness direction by applying a high-frequency electric signal to an electrode of the piezoelectric element. A circumferential traveling wave is generated at the end or side of the Langevin-type piezoelectric vibrator by combining the torsion vibration with the screw of the bolt, and a driven body is combined with the end or side. An ultrasonic driving device characterized by the above-mentioned. 2. A third substance such as a wear-resistant substance or a vibration transmitting substance is interposed between an end or a side of the Langevin type piezoelectric vibrator and the driven body. 2. The ultrasonic driving device according to claim 1, wherein: