JPH02294280A - Tubular electrostrictive rotor and motor - Google Patents

Abstract

PURPOSE:To increase the output of a rotor by a method wherein a piezoelectric ceramic pipe is provided with a common electrode on one circumferential sur face and with 4-phase exciting electrodes, divided into four equal segments, on the other circumferential surface. CONSTITUTION:An ultrasonic motor is provided with a tubular electrostrictive rotor 10. The rotor 10 is constituted of a common electrode 3, provided on the whole surface of the inner circumferential surface of a pipe 1, and belt type individual electrodes 4-7 provided on the outer circumferential surface of the same. 2-phase oscillator 9 is connected between the discrete electrodes 4, 6 and the discrete electrodes 5, 7 and 4-phase AC voltage, whose phases are deviated by 90 deg. respectively is impressed on the electrodes.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an ultrasonic vibrator and an ultrasonic motor using the same, and particularly relates to a pipe-shaped electrostrictive rotator and an ultrasonic motor using the same. It is.

[Prior Art] In the field of high-intensity ultrasonic technology, the overwhelming majority of technologies apply vertical vibration, and a Langevin oscillator is used as the vibration source. Recently, ultrasonic motors have been developed, requiring strong elliptical vibration, and various elliptical vibrators have been proposed.

By the way, the present inventor has proposed an ultrasonic motor that does not rely on mere elliptical vibration, that is, a "center of gravity rotation type ultrasonic motor" (Japanese Patent Application No. 11374/1983).The ultrasonic vibrator used in this motor is Rotating oscillator (patent application 1986)
11373), this piezoelectric vibrator is polarized in the thickness direction so that the semicircular portions have opposite polarities.

[Problem to be solved by the invention] In order to generate strong vibrations, the structure should be made of a thin plate with a large area and not a small admittance in order to increase the amount of applied electricity, but since the diameter is related to the resonant frequency, However, when the frequency to be applied is determined, the diameter of the vibrator is determined, and therefore the area is determined, and if it is made into a thin pipe shape, the excitation frequency becomes too high, making it difficult to excite efficiently. On the other hand, in fields such as medical endoscopes and drills, thin pipe-shaped motors with a diameter of about 3 m are showing promise. The purpose of the present invention is to eliminate such drawbacks of the prior art,
The object of the present invention is to provide a pipe-shaped electrostrictive rotor that can obtain a strong output, and a motor using the same.

[i9! Means for Solving the Problem] In order to achieve this object, the present invention provides a pipe made of piezoelectric ceramic whose axial length is longer than its circumferential length, and a pipe whose inner and outer circumferential surfaces are It has a common electrode provided on almost the entire surface of one of the pipes, and a polarized electrode divided into two parts on the other of the inner peripheral surface and the outer peripheral surface of the pipe, and the polarized electrode is polarized with the common electrode. By applying a voltage between the pipe and the electrode, two regions obtained by dividing the pipe along the axial direction are polarized to opposite polarities in the thickness direction of the pipe, forming a positive region and a negative region. It is characterized by being configured to: In order to achieve the above-mentioned object, the present invention further provides a pipe made of piezoelectric ceramic whose axial length is longer than its circumferential length, and one of the inner circumferential surface and outer circumferential surface of the pipe. A common electrode is provided on almost the entire surface of the pipe, and a polarized electrode is divided into two parts on either the inner peripheral surface or the outer peripheral surface of the pipe, and a polarized electrode is provided between the common electrode and the polarized electrode. By applying a voltage, the two regions obtained by dividing the pipe along its diameter along the axial direction are polarized to opposite polarities in the thickness direction of the pipe to form a positive region and a negative region, and then are bisected. The polarized electrode is short-circuited and used as one single-phase excitation electrode, or the polarized electrode is further divided into two and used as a four-phase excitation electrode. It is characterized by comprising a movable element that moves in contact with the child.

[Function] In the four-phase excitation type described above, a common electrode is provided on one side of the pipe made of piezoelectric ceramic, and a four-phase excitation electrode divided into four equal parts is provided on the other peripheral surface, and the common electrode and each individual electrode are connected to each other. By applying voltages with different phases by π/2 between the pipes, it is possible to excite a mode in which the center of gravity of the pipe revolves on the circumference around the center, and by adjusting the frequency, it is possible to make this mode resonate. On the other hand, in the single-phase excitation type, a single-phase resonant voltage can be applied between the single-phase excitation electrode and the common electrode to cause the revolution mode to resonate. In the present invention, a resonator in a mode in which the center of gravity revolves around the center is referred to as an electrostrictive resonator. By the way, the resonant frequency of this electrostrictive rotor does not depend on the diameter of the pipe, but on the length of the pipe, so if you increase the length of the pipe, you can obtain a low resonant frequency even with a thin pipe. A strained revolving element and an ultrasonic motor using the same can be obtained.

[Example] Next, an example of the present invention will be described with reference to the drawings. Fig. 1 is a perspective view of the pipe, Fig. 2 is a wiring diagram of an electrostrictive rotor using the pipe, Fig. 3 is a sectional view taken on line X-X of Fig. 2, and Figs. 4 (a), (b). ). (c) and (d) are explanatory diagrams showing the state of piezoelectric deformation in the electrostrictive rotor. The vip 1 is made of Pb (Zr Ti) O type piezoelectric ceramic, and its axial length L is equal to the circumferential length (π
D) is designed longer and has a hollow hole 2.

As shown in FIG. 2, a common electrode 3 is provided on the inner circumferential surface of the pipe 1 over almost the entire surface thereof, and individual electrodes 4, 5, 6 in the form of strips with approximately the same area are provided on the outer circumferential surface of the pipe 1. ．．
7 has been applied. As shown in the figure, the common electrode 3 is grounded, and the individual electrodes 4 and 6 and the individual electrodes 5 and 7
were connected in common, and polarization was performed by applying positive and negative DC high voltages to each. The arrow 8 in the figure indicates the polarization direction, and by this polarization process, the two regions obtained by dividing the pipe 1 in the diametrical direction along the axial direction are polarized with opposite polarities toward each other in the thickness direction of the pipe 1. A positive region and a negative region are formed. A two-phase oscillator 9 is connected between the individual electrodes 4 and 6 and the individual electrodes 5 and 7, and a frequency of 4
A four-phase AC voltage of 0 KHz and 50 V with a phase shift of 90' is applied. In this way, a pipe-shaped electrostrictive rotor 10 is constructed. FIG. 4 is a diagram showing the state of piezoelectric deformation of the electrostrictive rotor 10. In the figure, the electrostrictive rotor 10 shown by a solid line is when a voltage is applied, and the electrostrictive rotor 10 shown by a dotted line is when no voltage is applied. It shows the status of. Voltages with different phases of 90° are sequentially applied to individual electrodes 4 to 7.
, the center of gravity G revolves around the center O of the pipe 1, as shown in (a) to (d) of the figure. If the resonance frequency is set to 40Kl{z as mentioned above, the revolution speed will be 240X10'r. p. m. becomes extremely fast.

FIG. 5 is a diagram showing a modification of the electrostrictive rotor 10. In this example, individual electrodes 4 to 7 are attached to the inner peripheral surface of the pipe 1, and a common electrode 3 is attached to the outer peripheral surface. Since the method of connecting the individual electrodes 4 to 7 is the same as the example shown in FIG. 2, their explanation will be omitted. 6 to 13 are diagrams for explaining each embodiment of an ultrasonic motor using the electrostrictive rotor 10. FIG. Note that in these figures, descriptions of electrodes and the like are omitted to avoid complicating the drawings.

6 and 7 are a perspective view and a side view showing a first embodiment of the motor. In this embodiment, a rotating shaft 11 is inserted into a hollow hole of an electrostrictive rotor 10. In this embodiment, when using the electrostrictive rotator lO having the structure shown in FIG. ! It is necessary to provide a marginal membrane. By applying a voltage having a predetermined resonant frequency to the electrostrictive rotor 10, the electrostrictive rotor 1o moves as shown in FIGS.
) as shown, the center of gravity G moves, and as shown by the dotted line in FIG. 6, it curves sequentially along the axial direction. Therefore, even if the rotary shaft 11 is lightly inserted into the hollow hole of the electrostrictive rotor 10, the deformation of the electrostrictive rotor 10 as described above causes the partial pressure contact, and rotational force is applied to the rotary shaft 11, causing the rotation shaft 11 to move as shown by the arrow. Rotate in a predetermined direction as shown.

FIG. 8 and FIG. 9 are diagrams for explaining a second embodiment of the ultrasonic motor. In the case of this embodiment, the rotating cylinder 12 is fitted onto the electrostrictive rotor 10, and the rotating cylinder 12 is rotated by piezoelectric deformation of the electrostrictive rotor 10. FIG. 10 is a diagram for explaining a third embodiment of the ultrasonic motor, in which a rotating shaft 11 that is rotatably supported is connected to an electrostrictive rotor 10 in pressure contact with the outer peripheral surface of the electrostrictive rotor 10. The deformation causes the rotating shaft 11 to rotate in a predetermined direction.

FIG. 11 is a diagram for explaining a fourth embodiment of the ultrasonic motor, in which a moving body 13 such as an IC card, a magnetic card, or a transfer paper is pressed against the outer peripheral surface of an electrostrictive rotor 10 by a roller 14. There is. The piezoelectric deformation of the electrostrictive rotor 10 causes the movable body 13 to move in a predetermined direction.

FIG. 12 is a diagram for explaining a fifth embodiment of the ultrasonic motor. In this embodiment, the electrostrictive rotor 1o of the rotating disk 15 is lightly elastically contacted by a spring 16 on one end surface thereof. In the figure, 17 is a bolt and 18 is a base. FIG. 13 is a diagram for explaining a sixth embodiment of the ultrasonic motor. In the case of this embodiment, two rollers 20 having V grooves 19 on the inside are provided with springs 16 at both ends of the electrostrictive rotor 10.
is bombarded by.

[Effects] Since the present invention has the above-described configuration, it is possible to obtain a large output based on the electrostrictive rotor, and it is possible to use it in various applications such as, for example, a watch or a pubic part of a gastrocamera.

[Brief explanation of the drawing]

All drawings are for illustrating embodiments of the present invention.
Fig. 1 is a perspective view of the pipe, Fig. 2 is a wiring diagram of an electrostrictive rotor using the pipe, Fig. 3 is a sectional view on Fig. 2 x-xi, Fig. 4 (a), (b) ), (c), and (d) are explanatory diagrams showing states of piezoelectric deformation in the electrostrictive rotor, and FIG. 5 is a partially sectional plan view showing a modified example of the electrostrictive rotor. 6 and 7 are perspective views and side views of the ultrasonic motor according to the first embodiment, and FIGS. 8 and 9 are the second embodiment.
10, 11, 12, and 13 are explanatory diagrams of ultrasonic motors according to other embodiments. 1...pipe, 2...hollow hole, 3...
...Common electrode, 4,5,6,7...Individual electrode, 8...Polarization direction, 9...Two-phase oscillator, 10...・Electrostrictive rotor, 11...Rotating shaft, 12...Rotating cylinder, 13...
・・Mobile object, 14.20・・・・Roller, 15・・
...Rotating disk. Figure 1 Figure 4 (a) (b) (C) (d) Figure Figure Figure 11 Figure 12 Figure Figure lθ Figure Figure 13

Claims (2)

[Claims] (1) A pipe made of piezoelectric ceramic whose axial length is longer than its circumferential length, and a common electrode provided on almost the entire surface of either the inner or outer peripheral surface of the pipe. , has a polarized electrode divided into two equal parts on either the inner circumferential surface or the outer circumferential surface of the pipe, and by applying a voltage between the common electrode and the polarized electrode, the pipe is divided in diameter. A pipe-shaped electric current characterized in that the two regions divided along the axial direction are polarized to opposite polarities toward each other in the thickness direction of the pipe to form a positive region and a negative region. Distortion rotor. (2) A pipe made of piezoelectric ceramics whose axial length is longer than its circumferential length, and a common electrode provided on almost the entire surface of either the inner or outer peripheral surface of the pipe. , has a polarized electrode divided into two equal parts on either the inner circumferential surface or the outer circumferential surface of the pipe, and by applying a voltage between the common electrode and the polarized electrode, the pipe is divided in diameter. A pipe-shaped electrostrictive revolving element configured such that two regions divided along the axial direction are polarized to opposite polarities toward each other in the thickness direction of the pipe to form a positive region and a negative region; An ultrasonic motor comprising an electrostrictive rotor and a movable element that moves in contact with the rotor.