JPH03239169A - Ultrasonic oscillator and ultrasonic motor - Google Patents

Abstract

PURPOSE:To keep a pressure welding power of an elastic body and an exciter, which excites ultrasonic oscillation to the elastic body, constant by using as a fastening member a shape-memory alloy in which the specified shape is stored in advance. CONSTITUTION:In fastening members 4a, 4b made of shape-memory alloy, the shape which will have the following sizes at the specified temperature (t) is stored; r2 in diameter and l2 in length for a bar-shaped part 42a, b2 in diameter for a cylinder-shaped part 43a and b2 in diameter for a central hole 41b. When building up a Langevin oscillator 1, the fastening members 4a, 4b are transformed to the shape having the following sizes; r1 in diameter and l1 in length for the bar-shaped part 42a, a1 in diameter for the cylinder-shaped part 43a and b1 in diameter for the central hole 41b. Then, the elastic bodies 2a, 2b, piezoelectric bodies 3a, 3b and the fastening member 4b are piled up and then the fastening member 4a is passed through the central hole 41b. With the temperature of the fastening members 4a, 4b set at the specified one (t), the fastening of the Langevin oscillator 1 is completed by a shape-memory effect of the fastening members 4a, 4b.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an ultrasonic vibrator and an ultrasonic motor, and more particularly to a fastening member between an elastic body and an excitation body that constitute an ultrasonic vibrator. be.

[Prior Art] Conventionally, in an ultrasonic vibrator such as a Langevin type vibrator, in which an elastic body and a piezoelectric body that excites ultrasonic vibrations must be fastened to the elastic body, bolts and nuts are used as fastening members. was. An example of this is shown in FIG. The Langevin type vibrator 100 is an elastic body 101a made of metal and having a through hole in the center.

10lb, consisting of piezoelectric bodies 102a and 102b that excites axial stretching vibration in the elastic bodies 101a and 101b,
The elastic bodies 101a, 101b and the piezoelectric body 102
a and 102b are pressed together with a bolt 103 and a nut 104 at a predetermined pressure.

This predetermined pressure is controlled by torque for tightening the bolt 103.

[Problem to be solved by the invention] In the ultrasonic transducer having the above configuration, the bolt 1
Depending on the condition of the contact surface (area A in Figure 4) between the elastic body 101a and the elastic body 101a, the elastic body 1 may be tightened with the same torque.
01a, 101b, 'Since the pressure acting between the piezoelectric bodies 102a and 102b changes, the output characteristics of the ultrasonic transducer change. Therefore, the contact surface A between the bolt 103 and the elastic body 101a
It was necessary to keep the state constant. However, it is extremely difficult to keep the contact surface A constant because it is necessary to precisely control various conditions such as humidity and the amount of lubricating oil.

The present invention has been made to solve the above-mentioned problems, and is an excitation method that excites ultrasonic vibrations in an elastic body and the elastic body without being affected by the state of the contact surface between the elastic body and the fastening member. It is an object of the present invention to provide an ultrasonic vibrator and an ultrasonic motor that can easily maintain a constant pressure contact force with a body.

[Means for Solving the Problem] To achieve this object, the ultrasonic transducer of the present invention includes an elastic body, an excitation body that excites ultrasonic vibrations in the elastic body, and the elastic body and the excitation body. An ultrasonic transducer comprising a fastening member that integrates a It is characterized by

Further, the vibration excited in the elastic body is a substantially elliptical vibration, the elastic body has an axially symmetrical shape, and at least a shear vibration is excited in the elastic body. Furthermore, the ultrasonic motor of the present invention is characterized in that a movable element is brought into contact with a predetermined position of the above-mentioned ultrasonic vibrator.

[Function] The ultrasonic vibrator and ultrasonic motor of the present invention having the above-mentioned configuration use a shape memory alloy in which a predetermined shape is memorized as a fastening member, so that the fastening member can be deformed to transmit ultrasonic waves. After assembling the vibrator, the temperature of the fastening member is set to a temperature at which it recovers its shape, so that the elastic body and the excitation body can be easily brought into pressure contact with each other.

[Example] Hereinafter, an example embodying the present invention will be described with reference to the drawings.

FIGS. 1(a) and 1(b) are perspective views showing the state of the Langevin vibrator before and after fastening. First, the structure and operation of the Langevin oscillator of this embodiment will be explained with reference to FIG. 1(a). The Langevin vibrator 1 consists of elastic bodies 2a, 2b, piezoelectric bodies 3a, 3b sandwiched between the elastic bodies, and fastening members 4a, 4b. The fastening member 4a has a disk portion 41a.
, a rod-shaped portion 42a, and a cylindrical portion 43a, and the fastening member 4b has a center hole 41b.

4b is made of shape memory alloy. The fastening member 4a
, 4b is the diameter of the rod-shaped portion 42a "2.
A shape having dimensions of length Z21, diameter b2 of the cylindrical portion 43a, and diameter b2 of the center hole 41b (here, b2=r2.az>b2) is stored.

When assembling the Langevin vibrator 1, first the shapes of the fastening members 4a and 4b are determined by the diameter rl of the rod-shaped portion 42a and the length 1.
11 Diameter al of the cylindrical part, diameter bz of the center hole (here, >rl, al <b+, (11>12)
The elastic bodies 2a, 2b and the piezoelectric bodies 3a, 3b
, the fastening members 4b are stacked in the order shown in FIG. 1, and the fastening member 4a is passed through the center hole. After that, if the temperature of the fastening members 4a, 4b is set to the predetermined temperature t, the fastening members 4a, 4b
Due to the shape memory effect, the Langevin vibrator 1 is completely fastened (see FIG. 1(b)).

The piezoelectric bodies 3a and 3b of the Langevin vibrator 1 configured as described above are connected to an AC power source (not shown) via electrodes (not shown), and when an electric signal of a predetermined frequency is applied from the AC power source, the piezoelectric bodies 3a, 3b become elastic bodies. Stretching vibrations are excited in 2a and 2b.

Next, the structure and operation of the ultrasonic transducer of the second embodiment will be explained with reference to FIG. FIG. 2 is a sectional view of the ultrasonic transducer of the second embodiment. The ultrasonic transducer 10 includes disc-shaped elastic bodies 11a, llb, ff elastic bodies 11a, ll
The first piezoelectric body 12a, 1 which excites axial bending vibration in b
2b, a second piezoelectric body 13a, 1.3b that excites circumferential shear vibration in the elastic bodies 11a, llb, and the elastic body 1;
It consists of fastening members 14a, 14b that fasten 1a, 11b and the second piezoelectric bodies 13a, 13b with a predetermined pressure, and a holding member 15 that holds the ultrasonic vibrator 10.

The first piezoelectric bodies 12a, 12b include the elastic body 11a,
It is adhesively fixed to llb. Further, the elastic body 11. a
, llb have their shapes and dimensions adjusted so that the resonance frequencies of their axial bending vibrations and circumferential shear vibrations match. The fastening members 4a and 4b are attached to the rod-shaped portion 1 at a predetermined temperature T in advance.
The diameter of 41a is R2, the length is L23, and the diameter A2 of the cylindrical portion 142a is stored. When assembling the ultrasonic transducer 10, the shape of the fastening members 14a and 14b is adjusted to have a rod-shaped portion R3° and a length Ll, similar to the first embodiment described above.
, diameter of the cylindrical part B, (where B,>R,.

A,<B,,L,>L,), and the elastic bodies 11a, llb, second piezoelectric bodies 13a, 1
3b are overlapped and the fastening member 1.4a is passed through the center hole, and then the temperature of the fastening members 14a and 1.4b is set to the predetermined temperature T. The conclusion of the contract is completed.

First piezoelectric body 1 of ultrasonic transducer 10 configured as described above
2a, 12b and the second piezoelectric bodies 13a, 1.3b from a power source (not shown), the elastic body 1
Approximately elliptical vibrations are excited on 1a and llb.

Furthermore, with reference to FIG. 3, the structure and operation of the ultrasonic motor of this embodiment will be explained. FIG. 3 is a sectional view of the ultrasonic motor of this embodiment. Note that in this figure, members given the same reference numerals as in FIG. 2 indicate the same members. The ultrasonic transducer 10 shown in FIG. 2 is fixed to a motor body 16 via a holding member 15. The motor body 16 has an output shaft 1
7 is rotatably supported via a bearing 18.

One end of the output shaft 17 projects outward from the motor body 16, and a rotor 19 is attached to one end on the inside of the motor body 16.
is installed. The rotor 12 is pressed into contact with the elastic body 11a by a spring 20.

When a predetermined electrical signal is applied from a power supply (not shown) to the first and second piezoelectric bodies 12a, 12b, 13a, and 13b of the ultrasonic motor configured as described above, a substantially elliptical shape is formed on the elastic body 11a as described above. Vibrations are excited, and rotational force is applied to the rotor 19 by the approximately elliptical vibrations, making it possible to extract motor output from the output shaft 17.

Note that the present invention is not limited to the embodiments described in detail above (and various modifications can be made without departing from the spirit of the invention. For example, in this embodiment, a Langevin oscillator and a disk-type ultrasonic transducer are used. Although the sonic motor has been described, it goes without saying that similar effects can be obtained with any device that requires connecting an elastic body and an excitation body.

[Effects of the Invention] As is clear from the detailed description above, according to the present invention, the tightening pressure between the elastic body and the excitation body can be easily kept constant regardless of the state of the contact surface between the elastic body and the fastening member. It becomes possible to

[Brief explanation of drawings]

1 to 3 show embodiments embodying the present invention, and FIGS. 1(a) and 1(b) are perspective views showing the Langevin oscillator of the first embodiment, FIG. 2 is a sectional view showing an ultrasonic vibrator of a second embodiment, and FIG. 3 is a sectional view showing an ultrasonic motor of this embodiment. Further, FIG. 4 is a perspective view showing an example of the configuration of a conventional Languno-kun oscillator. In the figure, 2a, 2b, lla, llb are elastic bodies, 3a, 3
b is a piezoelectric body, 4a, 4b, 14a, 14b are fastening members,
13a and 13b are second piezoelectric bodies, and 19 is a rotor.

Claims (1)

[Scope of Claims] 1. An ultrasonic vibrator comprising an elastic body, an excitation body that excites ultrasonic vibrations in the elastic body, and a fastening member that integrates the elastic body and the excitation body, wherein the fastening member includes: An ultrasonic transducer characterized in that part or all of its members are made of a shape memory alloy. 2. The ultrasonic transducer according to claim 1, wherein the vibration excited in the elastic body is a stretching vibration of the elastic body. 3. The ultrasonic transducer according to claim 1, wherein the vibration excited in the elastic body is a substantially elliptical vibration. 4. The ultrasonic transducer according to claim 3, wherein the elastic body has an axially symmetrical shape, and at least shear vibration is excited in the elastic body. 5. An ultrasonic motor, characterized in that a movable element is brought into contact with a predetermined position of the ultrasonic vibrator according to claim 3 or 4.