JPH0870589A - Ultrasonic piezoelectric transducer and ultrasonic motor - Google Patents

Abstract

PURPOSE: To provide an ultrasonic piezoelectric transducer which efficiently propagates ultrasonic elliptical oscillation and can embody small-sized rotary ultrasonic motors. CONSTITUTION: An ultrasonic piezoelectric transducer 10 consists of at least two electromechanical transducing elements 12; an elastic body 11 to which the electromechanical transducing elements 12 are bonded; and at least two drivers 14. The piezoelectric transducer synthesized two oscillation modes to generate ultrasonic elliptical oscillation. The elastic body 11 is formed into an arc shape, and a recess 11a is formed in at least two places on the circumfrence of the elastic body. The electromechanical transducing elements 12 are placed in the recesses.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic vibrator and an ultrasonic motor using the same.

[0002]

2. Description of the Related Art In recent years, ultrasonic motors have attracted attention as new motors to replace electromagnetic motors. This ultrasonic motor has the following advantages over conventional electromagnetic motors. (1) Low speed and high thrust can be obtained without gears. (2) Large holding power. (3) The stroke is long and the resolution is high. (4) It is extremely quiet. (5) Magnetic noise is not generated, and the influence of noise is not exerted.

Conventionally, an ultrasonic transducer and an ultrasonic motor using the same have been filed by the applicant of the present invention in Japanese Patent Laid-Open No.
The technology described in Japanese Patent Laid-Open No. 105571 is disclosed. FIG. 7 is a perspective view of an ultrasonic transducer which is an electric-mechanical energy conversion element which is a main part of the ultrasonic motor of the prior art. In this ultrasonic transducer 110, three holding elastic bodies 112 are fixed to the upper surface of a basic elastic body 111, and the laminated piezoelectric elements 113A and 11A are provided between the respective holding elastic bodies 112.
3B is clamped and fixed.

The basic elastic body 111 is a brass material processed into a rectangular parallelepiped shape. The holding elastic bodies 112 are fixed with epoxy adhesives at three locations on both ends and the central portion of the upper surface, and the screws 114 are further fixed. ing. Then, the laminated piezoelectric elements 113A and 113B are abutted and held between the respective holding elastic bodies 112. That is, the laminated piezoelectric element 113
A and 113B are adhesively fixed to the holding elastic body 112 so as not to contact the basic elastic body 111. The side surfaces of the laminated piezoelectric elements 113A and 113B are resin-coated. Here, the laminated piezoelectric element 113 on the left side of FIG.
The electrodes to A will be referred to as A and G, and will be referred to as A phase. Similarly, let B and G be electrodes to the laminated piezoelectric element 113B on the right side, and
I will call it Ai.

Sliding members 115 are adhered to both ends of the bottom surface of the basic elastic body 111. The sliding member 115 is made of polyimide mixed with carbon fiber (20% by weight) and mica (30% by weight) as a filler, and has a thickness of about 0.1 mm.

Next, the operation of the ultrasonic transducer will be described. According to the computer simulation, the ultrasonic transducer having the above dimensions can excite the primary resonant longitudinal vibration as shown in FIG. 8 and the secondary resonant bending vibration as shown in FIG. 9 at substantially the same frequency. Its frequency is 53.5 kHz. Therefore, a DC voltage of 30 V is applied to the A phase and the B phase to apply compression preload to the laminated piezoelectric elements 113A and 113B, and the A phase and the B phase have a frequency of 53.5 kHz and an amplitude of 10
An alternating voltage of Vp-p is applied. Here, if the phases of the A phase and the B phase are made to be the same phase, primary resonant longitudinal vibration as shown in FIG. 8 is excited. Next, when the phases of the A phase and the B phase are made opposite to each other, a secondary resonance bending vibration as shown in FIG. 9 is excited. Next, if the phases of A phase and B phase are shifted by 90 degrees,
Ultrasonic elliptical vibration can be excited near the sliding member 115.

The ultrasonic elliptical motion excited on the sliding member 115 moves the moving body in contact therewith. The moving direction of the moving body is changed by setting the phase difference between the voltages applied to the electrodes A phase and B phase of the laminated piezoelectric elements 113A and 113B to +90 degrees or -90 degrees.

Next, an ultrasonic linear motor using the above ultrasonic vibrator will be described. FIG. 10 is a front view of the ultrasonic linear motor. As shown in the figure, in this ultrasonic linear motor, the ultrasonic transducer 110 is designed to be self-propelled to the left and right on the rail 121, and the linear guide moving portion 123 is provided on the back surface of the rail 121 to guide this.
Is provided.

The ultrasonic vibrator 110 is held by a vibrator holding member 124 made of an aluminum material through a silicon rubber (not shown) having a thickness of 1 mm. The vibrator holding member 124 has a U-shape and is connected with a connecting rod 125. A spring receiver 126 is provided on the upper end of the connecting rod 125.
Are formed. On the other hand, the rail 121 is made of a stainless material whose surface is quench hardened, the surface is smoothly polished, and the linear guide fixing portion 122 is integrally fixed to the rear surface. The frame 13 is provided on the linear guide moving unit 123.
0 is fixed and is integrated with the upper frame 131.
The center portion of the upper frame 131 is tapped and a bolt 129 is screwed therein. A spring retainer 128 is attached to the bolt 129 so that the length of the spring 127 can be adjusted and the contact pressure between the ultrasonic transducer 110 and the rail 121 can be adjusted.

Next, the operation of this ultrasonic motor will be described. As described above, the alternating voltage is applied to the A phase and the B phase of the ultrasonic transducer 110 to set the phase difference to 90 degrees (or −90 degrees). Then, ultrasonic elliptical vibration is excited on the sliding surface of the ultrasonic transducer 110, and the ultrasonic vibrator 110 moves to the right (or left) with respect to the rail.

According to this prior art, since the piezoelectric longitudinal effect is utilized by using the laminated piezoelectric element, the electromechanical conversion efficiency is improved and the low voltage driving becomes possible. Further, it is possible to obtain an ultrasonic linear motor having a large output with a very simple structure and being compact, and since the laminated piezoelectric element is used while being preloaded, the durability of the motor can be improved.

[0012]

However, using the conventional ultrasonic transducer 110 shown in FIG. 7 described above,
When an attempt is made to configure a rotary ultrasonic motor, as shown in FIG. 6, the ultrasonic transducer 110 and the rotating body 101 rotating about the rotation shaft 102 are the sliding members 115 of the ultrasonic transducer 110. Therefore, there is a problem that the motor itself becomes large and the efficiency of propagation of ultrasonic elliptical vibration excited in the ultrasonic transducer 110 is not good.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide a rotary ultrasonic motor which is small in size and has high efficiency of propagation of ultrasonic elliptical vibration. An object is to provide an ultrasonic transducer that can be realized. An object of the invention according to claim 3 or 4 is to provide a small-sized rotary ultrasonic motor using the ultrasonic vibrator.

[0014]

In order to solve the above problems, the invention according to claim 1 or 2 provides at least two electromechanical conversion elements, an elastic body to which the electromechanical conversion elements are fixed, and at least two electromechanical conversion elements. In the ultrasonic transducer that is composed of two driver elements and generates two ultrasonic vibration modes to generate ultrasonic elliptical vibration, the elastic body has a circular arc shape, and the elastic body has a circular arc shape along the inner and outer peripheral surfaces thereof. The electromechanical conversion element is provided by providing recesses in at least two places. The invention according to claim 3 or 4 is characterized by comprising the ultrasonic vibrator according to claim 1 and a rotor that is pressed and held against a driver of the ultrasonic vibrator.

[0015]

In the operation of the invention according to claim 1 or 2, the elastic body is formed into an arc shape, and the extension vibration of the arc of the elastic body is generated.
The ultrasonic elliptical vibration is generated at each part of the surface of the elastic body by combining with the bending vibration in the arc surface of the elastic body. The ultrasonic elliptical vibration propagates to the rotating body that is in contact with the ultrasonic elliptical vibration through the two driving elements, but when the axis of the rotating body is aligned with the center of the arc of the elastic body, the ultrasonic elliptical vibration works most efficiently.
In the operation of the invention according to claim 2, in addition to the above-mentioned operation, since the plurality of ultrasonic transducers are arranged on the inner and outer circumferences, the ultrasonic elliptical vibration is strongly excited. In the operation of the invention according to claim 3 or 4, since the surface of the rotor is pressed against the driver of the ultrasonic vibrator according to claim 1, ultrasonic elliptical vibration propagates from the driver and the rotor rotates. To do. In the operation of the invention according to claim 4, in addition to the above-mentioned operation, since the plurality of ultrasonic vibrators are provided surrounding the rotor, the rotational force of the rotor becomes strong.

[0016]

Embodiment 1 FIGS. 1 to 4 show a first embodiment, FIG. 1 is a schematic configuration diagram of an ultrasonic oscillator, FIG. 2 is a state diagram showing the action of the ultrasonic oscillator, and FIG. 3 is an ultrasonic motor. FIG. 4 is a front view showing a modification of the ultrasonic motor.

In FIG. 1, (a) shows an ultrasonic transducer 10
Is a front view, and (b) is a side view. An elastic body 11 is made of a copper alloy such as brass. The elastic body 11 has an arc shape, and as shown in the drawing, recesses 11a are provided at two symmetrical positions along the arc outer peripheral surface. A laminated piezoelectric element 12, which is an electromechanical conversion element, is inserted and arranged in the recess 11a in a state in which a compressive force is applied in the laminating direction, and is bonded by an epoxy resin on all surfaces that come into contact with the elastic body 11. . The laminated piezoelectric element 12 is a laminated piezoelectric element NLA-2 × 3 × 9 manufactured by Tokin Co., Ltd., which is formed by laminating several tens to several hundreds of electrode-treated piezoelectric elements. Its dimensions are 2 mm x 3.1 mm x 9 mm. The laminated piezoelectric element 12 is covered with an epoxy resin, although not shown, except for the both end surfaces (coating thickness: about 20 μm).

As shown in the drawing, a driver element 14 made of a grindstone material is fixed at two locations on the inner peripheral surface of the arc of the elastic body 11. The fixed position of the driver element 14 coincides with the position where the amplitude of the bending vibration shows a maximum. In addition, a pin 13 made of a stainless steel material having a diameter of φ2 is inserted into the elastic body 11 at the center of the elastic body 11 so as to project from the front and back. The position of the pin 13 coincides with the position of the common node of the expansion and contraction vibration of the primary arc and the secondary bending vibration of the arc. Further, in FIG. 1A, the electric terminals connected to the left laminated piezoelectric element 12 are A and GND (referred to as A phase), and the electric terminals connected to the right laminated piezoelectric element 12 are The terminals are B and GND (called B phase).

Next, the operation of the ultrasonic transducer 10 will be described. In the ultrasonic transducer 10, the expansion and contraction vibration of the primary arc as shown in FIG. 2A and the secondary bending vibration of the arc as shown in FIG. 2B are excited at substantially the same frequency. . The frequency is adjusted to about 53 kHz to 56 kHz. First, when an alternating voltage having an amplitude of 10 Vp-p with a frequency Fr is applied to the A-phase and an alternating voltage having the same frequency and the same amplitude and the same phase is applied to the B-phase, the primary voltage as shown in FIG. Stretching vibration of the arc is excited. Next, frequency A is added to phase A
When an alternating voltage with an amplitude of 10 Vp-p is applied at r and an alternating voltage with the same frequency and the same amplitude and opposite phase is applied to the B phase, a secondary bending vibration as shown in Fig. 2 (b) is excited. . When an alternating voltage with a frequency Fr and an amplitude of 10 Vp-p is applied to the A phase, and an alternating voltage with the same frequency and the same amplitude but a phase difference of ± π / 2 is applied to the B phase, the driver shown in FIG. An ultrasonic elliptical motion was excited at 14 positions.

The effect of the ultrasonic transducer 10 will be described. Since the elastic body 14 is formed in an arc shape and the driving body 14 is arranged on the inner peripheral surface thereof, when the rotating body is placed at the center of the arc, the ultrasonic elliptical motion works efficiently and the rotating body rotates. Is done smoothly.

Next, a rotary ultrasonic motor 20 using the above ultrasonic vibrator 10 will be described. In FIG. 3, reference numeral 21 is a rotor, which is composed of a rotating body of zirconia ceramics. A hole is provided in the center of the rotor 21, and the rotor 21 is rotatably fitted to the fixed shaft 22 via a bearing (not shown). Also. The axial center of the rotor 21 and the arc center of the ultrasonic transducer 10 are aligned with each other, and the ultrasonic transducer 10 and the rotor 21 are connected to each other by the spring 24.
The portions 4 are pressed and held together. The spring 24 is hooked and held between the pin 13 of the ultrasonic transducer 10 and the protrusion 23 provided at the center of the rotor 22. Further, in order to prevent the ultrasonic transducer 10 itself from rotating around the rotor 21, the pin 23 is fixed to a base (not shown).

Next, the operation of the ultrasonic motor 20 will be described. As described above, the phases A and B of the ultrasonic transducer 10 are
Frequency Fr (frequency between 53 kHz and 56 kHz) in phase,
An alternating voltage having an amplitude of 10 Vp-p and a phase difference of + π / 2 or −π / 2 is applied. Then, the rotor 20 rotated clockwise or counterclockwise at a rotation speed of about 120 rpm.

The effect of the rotary ultrasonic motor 20 will be described. Since the rotor 21 is arranged at the center of the circular arc of the ultrasonic transducer 10, the rotary ultrasonic motor can be downsized and efficient rotating force can be obtained.

A modification of the ultrasonic transducer 10 of this embodiment will be described. In this embodiment, as shown in FIG. 1A, the laminated piezoelectric element 1 is formed along the arc outer peripheral surface of the elastic body 11.
2 are arranged, and the driver element 14 is projected on the inner circumferential surface of the arc,
Conversely, the driver element 14 may be provided so as to project from the outer circumferential surface of the arc, and the laminated piezoelectric element 12 may be fixedly provided along the inner circumferential surface of the arc. In this case, the driven rotating body has an annular shape, and its inner peripheral surface comes into contact with the driver element 14. This is effective when the hollow rotating body is rotated and a space for holding the ultrasonic transducer cannot be provided on the outer peripheral portion of the hollow rotating body.

Next, a modification of the ultrasonic motor 20 of this embodiment will be described. FIG. 4 shows an ultrasonic motor 30 according to this modification. Reference numeral 31 is a rotor, and two ultrasonic transducers 10 are arranged so as to sandwich the rotor 31. A fixed shaft 32 supports the rotor 31.
A leaf spring 33 is fitted on the fixed shaft 32 and engages with the pin 13 of the ultrasonic transducer 10 at both ends to press the ultrasonic transducer 10 against the rotor 31. Since the two ultrasonic transducers 10 are arranged in this way, the output of the motor can be doubled. Although two ultrasonic transducers are arranged in the present modification, a plurality of ultrasonic transducers may be arranged.

[0026]

Second Embodiment FIG. 5 is a front view showing an ultrasonic transducer 40 of a second embodiment. The ultrasonic oscillator 40 of the present embodiment is basically the same as the ultrasonic oscillator 10 of the first embodiment, and therefore, the same members are given the same numbers and their explanations are omitted.

In FIG. 5, reference numeral 41 denotes an elastic body having an arc shape. Two recesses 41a are provided at symmetrical positions on the arc outer peripheral surface and the arc inner peripheral surface of the elastic body 41, and the laminated piezoelectric element 12 is fitted and fixed in the recesses 41a. A driver element 14 is fixed to the laminated piezoelectric element 12 on the inner peripheral surface side of the arc as shown in the figure. Since the laminated piezoelectric element 12 and the elastic body 41 are integrated by an adhesive, ultrasonic elliptical vibration is not limited to the laminated piezoelectric element 12 on the inner peripheral surface side of the arc, but the laminated piezoelectric element on the outer peripheral side of the arc. 12
The ultrasonic elliptical vibration of is also propagated to the driver 14. Further, the electric terminals A and A ′ connected to the four laminated piezoelectric elements 12
(Phase A) is connected, and electrical terminals B and B '(Phase B) are connected. Illustration of the ground terminal GND is omitted.

The operation of the ultrasonic transducer 40 of this embodiment will be described. Since the operation of the ultrasonic oscillator 40 is basically the same as that of the ultrasonic oscillator 10 of the first embodiment, only different parts will be described. When an alternating voltage having a frequency Fr and an amplitude of 10 Vp-p is applied to the A phase, and an alternating voltage having the same frequency and the same amplitude and a phase difference of ± π / 2 is applied to the B phase, the position of the driver 14 in FIG. The ultrasonic elliptical vibration was excited.

The effect of the ultrasonic transducer 40 will be described. In addition to the effect of the ultrasonic transducer 10 of the first embodiment, the double-layered piezoelectric element is used, so that the output of ultrasonic elliptical vibration can be increased.

The ultrasonic motor 20 of FIG. 3 shown in the first embodiment and the ultrasonic vibrator 1 of the ultrasonic motor 30 of FIG.
If the ultrasonic transducer 40 of this embodiment is used instead of 0,
Further, a rotary ultrasonic motor having a large output can be obtained.

In the first embodiment and this embodiment, the laminated piezoelectric element is used as the electromechanical conversion element.
Not limited to this, the same effect can be obtained by using a magnetostrictive element.

[0032]

According to the first and second aspects of the present invention, it is possible to provide an ultrasonic transducer having a high efficiency of propagation of ultrasonic elliptical vibration and capable of embodying a small rotary ultrasonic motor. it can. According to the invention of claim 2, in addition to the above effects, ultrasonic elliptical vibration can be strengthened. According to the invention according to claims 3 to 4, it is possible to provide a small rotary ultrasonic motor of high torque with a simple configuration. According to the invention of claim 4, in addition to the above effects, the output of the rotary ultrasonic motor can be increased.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an ultrasonic transducer of a first embodiment.

FIG. 2 is a state diagram showing the operation of the ultrasonic transducer of the first embodiment.

FIG. 3 is a schematic configuration diagram showing an ultrasonic motor according to a first embodiment.

FIG. 4 is a front view showing a modification of the ultrasonic motor according to the first embodiment.

FIG. 5 is a front view showing an ultrasonic transducer of a second embodiment.

FIG. 6 is a schematic configuration diagram for explaining a conventional technique.

FIG. 7 is a perspective view showing a conventional ultrasonic transducer.

FIG. 8 is a perspective view showing an operation of a conventional ultrasonic transducer.

FIG. 9 is a perspective view showing the operation of a conventional ultrasonic transducer.

FIG. 10 is a front view showing a conventional ultrasonic motor.

[Explanation of symbols]

 10 Ultrasonic Transducer 11 Elastic Body 11a Recess 12 Ultrasonic Transducer 13 Pin 14 Driver

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiro Awai 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Co., Ltd. (72) Inventor Yoshihisa Taniguchi 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Industry Co., Ltd.

Claims (4)

[Claims] 1. At least two electromechanical conversion elements,
An elastic body to which the electromechanical conversion element is fixed, and at least 2
An ultrasonic transducer that is composed of two driver elements and generates ultrasonic elliptical vibration by combining two vibration modes, wherein the elastic body has an arc shape, and the elastic body has an arc shape along the inner and outer peripheral surfaces. An ultrasonic transducer, wherein the electromechanical conversion element is provided by providing recesses at least at two positions. 2. The ultrasonic transducer according to claim 1, wherein the recesses in which the electromechanical conversion elements are arranged are provided at two locations on the outer peripheral portion and two locations on the inner peripheral portion of the elastic body. 3. An ultrasonic motor, comprising: the ultrasonic vibrator according to claim 1; and a rotor that is pressed and held by a driver of the ultrasonic vibrator. 4. The ultrasonic motor according to claim 3, wherein a plurality of ultrasonic vibrators according to claim 1 are provided so as to surround the rotor.