JPH07123747A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To constitute the vibrating body of an ultrasonic motor of a material having a high workability, corrosion resistance, and abrasion resistance so as to reduce the size and weight of the motor. CONSTITUTION:An Al-Mg alloy is used to make the vibrating body 100 of a small-sized ultrasonic motor. The alloy contains 4.5-5.6% Mg, 0.05-9.0% Mn, 0.05-0.2% Cr, 0.4% or less Fe, 0.1% or less Cu, 0.3% or less Si, and 0.1% or less ZnO, with the total content of all components except Al being equal to or less than 0.15% and the rest being Al. When the vibrating body 100 is constituted of such an Al-Mg alloy, the ultrasonic motor can be reduced in weight and, at the same time, the vibrating body can be improved in workability, corrosion resistance, and abrasion resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic motor for generating a driving force by exciting ultrasonic waves by electro-mechanical conversion such as piezoelectric and magnetostriction, and more particularly to a vibrating body of a small ultrasonic motor. Regarding materials.

[0002]

2. Description of the Related Art Conventionally, a metal material such as aluminum, iron, stainless steel, or brass has been used as a material for a vibrating body of an ultrasonic motor. There is one published in No. 141 (1992) as "Development of AQ with vibration alarm using ultrasonic motor".

Further, Japanese Unexamined Patent Publication No. 62-193575 and Japanese Unexamined Patent Publication No. 60-200778 disclose the material of the vibrating body of the conventional ultrasonic motor.

[0004]

However, as described above, as a material of the vibrator of the ultra-small ultrasonic motor, iron-based materials have a problem of corrosion resistance, and stainless-steel materials have a problem of workability. There is a problem that the resonance sharpness Q is small in the brass-based material, and there is a problem that the weight of the ultrasonic motor is large because the material has a large specific gravity.

Therefore, in order to solve such a conventional problem, an object of the present invention is to use an aluminum-based material having a small specific gravity as a material of a vibrating body to obtain a compact ultrasonic motor having good environment resistance. Especially. However, there are various alloys as aluminum-based materials, and each has its own characteristics. Especially for the vibrators of ultra-small ultrasonic motors, the resonance frequency becomes extremely high, and because of the fine structure, high precision is achieved. The materials to be used must be carefully selected because they require the machining of, and the corrosion resistance is required.

[0006]

In order to solve the above-mentioned problems, the present invention uses Al as a material of a vibrating body of an ultrasonic motor.
By using an alloy based on a Mg-based material, it is possible to reduce the weight and improve the workability and corrosion resistance.

[0007]

In the ultrasonic motor configured as described above, the weight of the vibrator is reduced by using the alloy based on the Al--Mg type material as the vibrator, and
Workability and corrosion resistance can be satisfied.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of an embodiment of the present invention will be described below with reference to the drawings. In each of the drawings of the embodiments, the same parts are designated by the same reference numerals, and the duplicated description will be omitted.

FIG. 1 is a sectional view showing the basic structure of a small ultrasonic motor according to the present invention. The central shaft 120 is the support plate 13
Fixed at 0. The center axis 120 is the disk-shaped vibrating body 10.
0 is supported at the center. The central axis 120 is the rotor 140.
To guide you. The mechanical resonance frequencies of the support plate 130 and the central shaft 120 are sufficiently separated so as not to interfere with the resonance frequency of the vibrating body 100, and the vibrating body 10 is affected by the support.
It has a support structure that does not cause zero vibration leakage and damping.

The piezoelectric element 110 is bonded to the lower surface of the vibrating body 100. The piezoelectric element 110 is driven by a high frequency AC signal, and ultrasonic vibration is excited in the vibrating body 100. In addition, a plurality of protrusions 101 are provided on the upper surface of the vibrating body 100 to magnify the minute displacement excited by the piezoelectric element 110.

The rotor 140, which constitutes the moving body, is constructed by joining the friction material 141 to the rotor body. Spring 150
It is arranged between the inner ring of the bearing 170 and the set screw 160. The friction material 141 is joined to the rotor body at the tip of the protruding portion 101 of the vibrating body. The rotor 140 pressurizes and contacts the friction material 141 by the spring 150. The rotor 140 rotates due to friction with the friction material 141.

FIG. 2 is a view showing the structure of the vibrating body 100. The support structure of the vibrating body 100 greatly affects the characteristics of the ultrasonic motor. In the ultrasonic motor of the present invention, the vibrating body 100 has a disk shape with a diameter of 10 mm or less. The center shaft 120 is driven in and supported by a hole provided at the center of the vibrating body 100. Even if the vibration of the vibrating body 100 is in the basic vibration mode or the higher-order vibration mode, the center portion serves as a node of the vibration, so that the support structure is simple and excellent.

Vibrating body 100 having a plurality of protrusions 101
Is manufactured by cutting the Al-Mg-based material of the present invention. The cross-sectional area of the plurality of protrusions 101 is 0.05 mm 2 or less, and the variation in the dimension of each protrusion is processed to 0.005 mm or less. Therefore, workability has the highest priority in material selection.

The problem in reducing the size and weight of the ultrasonic motor is to reduce the size of each component.
Since it is unavoidable that the resonance frequency becomes high, the mechanical vibration loss at high frequency should not be large. That is, the resonance sharpness Q of the vibrating body is prevented from becoming small.

The ultrasonic motor of the present invention utilizes the disk flexural vibration mode, and its resonance frequency F is expressed by the following formula 1.

[0016]

[Equation 1]

Here, k is a constant determined by the vibration mode, shape, etc. t: thickness of the vibrating body d: radius of the vibrating body E: longitudinal elastic coefficient of the vibrating body ρ: density of the vibrating body σ: Poisson's ratio

In addition, in order to prevent the circuit configuration, the ease of selection of circuit components and the electrical noise, it is desired that the resonance frequency F does not become high even if the ultrasonic motor is downsized. In order to reduce the outer shape of the vibrating body and prevent the resonance frequency from increasing, it is necessary to reduce the thickness t of the vibrating body. Therefore, since the protrusions and thickness of the vibrating body are extremely reduced, the working dimensional tolerance becomes extremely strict, the workability is good, and the material having high corrosion resistance is required.

Furthermore, since the vibrating body of the ultrasonic motor is in frictional contact with the friction material of the rotor, it is required to have high wear resistance and a small temperature coefficient of resonance frequency. Comparing the problems with the vibrating body in the case of miniaturizing the materials that may be used,
It is an evaluated table.

Although iron-based materials have excellent resonance sharpness at high frequencies, they are not sufficient in weight reduction, workability, corrosion resistance, and abrasion resistance. Although stainless steel (SUS) -based materials have excellent corrosion resistance and acceptable workability, they do not have sufficient weight reduction, resonance sharpness at high frequencies, and abrasion resistance.

On the other hand, the aluminum-based material is very excellent in weight reduction, has excellent resonance sharpness at high frequencies, workability, and abrasion resistance, and has acceptable corrosion resistance. It should be noted that none of the above materials has sufficient resonance frequency temperature characteristics. Therefore, it is obvious that the aluminum-based material is suitable as the material of the vibrating body when the ultrasonic motor is made ultra-small.

FIG. 4 shows the aluminum-magnesium system (Al-Mg system) of the present invention used in a compact ultrasonic motor.
3 is a table showing material components of the vibrating body of FIG. There are various alloys of aluminum-based materials, and each has its own characteristics. However, the vibration body of the Al-Mg-based material shown in FIG.
It is a material with improved corrosion resistance aimed at improving workability, especially machinability and surface finish.

(1) First Embodiment The component of the material A in FIG. 4 is the basic constitution of the first embodiment of the vibrator of the ultrasonic motor of the present invention. The component ratio of the material is preferably such that Mg is 4.5 to 5.6%, and Mn is
Is 0.05 to 9.0%, and Cr is 0.05 to 0.2.
%, Fe is 0.4% or less, Cu is 0.1%
Below, Si is below 0.3%, Zn is 0.1%
Below, 0.15% of the total of other components except Al
The following is an Al-Mg-based material in which the balance is Al.

(2) Second Embodiment The component of the material B in FIG. 4 is the basic constitution of the second embodiment of the vibrating body of the ultrasonic motor of the present invention. The material B is a material when workability is given the highest priority, and when compared with the component ratio of the material A, preferably, only Mn is an Al-Mg based material different from 0.05 to 0.2%.

(3) Third Embodiment The component of the material C in FIG. 4 is the basic constitution of the third embodiment of the vibrator of the ultrasonic motor of the present invention. The material C is a material aiming at a countermeasure against stress corrosion due to processing.

The component ratio of the material is preferably 4.5 to 5.6% for Mg, 0.1 to 0.6% for Mn, 0.2% or less for Cr, and Fe. 0.5% or less, Cu is 0.1% or less, Si is 0.4% or less, Zn is 0.2% or less, and the total of other components except Al is 0.15%. The following is an Al-Mg-based material in which the balance is Al.

Next, the function of each component in the material will be described. Mg improves workability, strength, and corrosion resistance. Mn increases the strength without impairing the corrosion resistance. Fe has an effect of refining crystal grains, and as a result, workability and strength are improved.
This is because Cr prevents stress corrosion cracking and suppresses recrystallization during hot working. Other components are the limits that should be economically removed as impurities.

Further, the interaction of Mn and Cr reduces stress corrosion due to working. The above-mentioned material C is aimed at this effect. In addition, in the above-mentioned example, when each ingredient is below the above-mentioned ingredient ratio, the effect will decrease.

On the other hand, when Mg is more than the above component ratio, intergranular corrosion and stress corrosion are likely to occur. When Fe is more than the above component ratio, the corrosion resistance becomes poor and the toughness becomes low. When Cu is more than the above component ratio, corrosion resistance deteriorates, and weldability and formability deteriorate.

Further, when the ratio of each of the other components is more than the above-mentioned component ratio, the effect thereof is reduced or other troubles occur. In the present invention, the embodiment is shown for the ultra-small ultrasonic motor having a diameter of 10 mm or less, but the present invention has a great effect also for a small ultrasonic motor having a diameter of 25 mm or less.

(4) Fourth Embodiment Further, based on the operation of the power transmission means that integrally operates with the rotor 140 that constitutes the moving body of the ultrasonic motor using the ultrasonic motor of the present invention, An electronic device with an ultrasonic motor can be realized by providing an output means that operates in accordance with the above.

As the power transmission means, transmission wheels such as gears and friction wheels are preferably used. As output means,
Preferably, a pointer is used in an electronic timepiece, a film feeding device or a lens driving device is used in a camera, a tool feeding device or a processing member feeding device is used in a machine tool, and an arm or the like is used in a robot.

As the electronic device with an ultrasonic motor of the present invention, preferably, an electronic timepiece, a camera, a printer, a printing machine, a machine tool, a robot, a moving device, etc. can be realized.

[0034]

As described above, according to the present invention, by using an alloy based on an Al-Mg-based material as a vibrating body of a small ultrasonic motor, the vibrating body can be made lighter and processed. By improving the durability and corrosion resistance, there is an effect that it is possible to provide a small ultrasonic motor with high accuracy and good environmental resistance.

[Brief description of drawings]

FIG. 1 is a sectional view showing a basic structure of an ultrasonic motor of the present invention.

FIG. 2 is a diagram showing a structure of a vibrating body of the ultrasonic motor of the present invention.

FIG. 3 is a table in which the problems associated with the vibrating body when the ultrasonic motor is downsized are compared and evaluated for materials that may be used.

FIG. 4 is a table showing material components of an Al—Mg-based vibrator of the present invention.

[Explanation of symbols]

 100 Vibrating Body 101 Vibrating Body Protruding Part 110 Piezoelectric Element 120 Central Shaft 130 Support Plate 140 Rotor 141 Friction Material 150 Spring 160 Set Screw 170 Bearing

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akihiro Iino 6-31-1, Kameido, Koto-ku, Tokyo Seiko Electronics Co., Ltd. (72) Kenji Suzuki 6-31-1, Kameido, Koto-ku, Tokyo No. Seiko Electronics Co., Ltd. (72) Inventor Emperor Yamazaki 6-31-1 Kameido, Koto-ku, Tokyo Seiko Electronics Co., Ltd. (72) Makoto Suzuki 6-31-1, Kameido, Koto-ku, Tokyo No. Seiko Electronics Co., Ltd. (72) Inventor Ryuki Inoue 6-31-1, Kameido, Koto-ku, Tokyo Inside Seiko Electronics Co., Ltd.

Claims (5)

[Claims] 1. An ultrasonic motor having a vibrating body (100) excited by a high-frequency AC signal and a moving body (140) frictionally driven by a vibration wave generated in the vibrating body (100), An ultrasonic motor, wherein the vibrating body (100) is made of an aluminum-magnesium-based material. 2. The vibrating body (100) is made of an aluminum-magnesium-based material, and the component ratio of the material constituting the vibrating body (100) is 4.5 to 5.6% for Mg and 0 for Mn. 0.05 to 9.0% and Cr of 0.05
~ 0.2%, Fe less than 0.4%, Cu less than 0.1%, Si less than 0.3%, Zn
Is 0.1% or less, the total amount of other components excluding Al is 0.15% or less, and the balance is Al. 3. The vibrating body (100) is made of an aluminum-magnesium-based material, and the material composition ratio of the vibrating body (100) is such that Mg is 4.5 to 5.6% and Mn is 0. 0.05 to 0.2% and Cr of 0.05
~ 0.2%, Fe less than 0.4%, Cu less than 0.1%, Si less than 0.3%, Zn
Is 0.1% or less, the total of other components excluding Al is 0.15% or less, and the balance is Al. 3. The ultrasonic motor according to claim 1, wherein 4. The vibrating body (100) is made of an aluminum-magnesium-based material, and the material composition ratio of the vibrating body (100) is such that Mg is 4.5 to 5.6% and Mn is 0. 1 to 0.6%, Cr is 0.2% or less, Fe is 0.5% or less, and Cu is 0.1%.
Or less, Si is 0.4% or less, and Zn is 0.2
% Or less, and the total of other components except Al is 0.15
% Or less, and the balance is Al, The ultrasonic motor according to claim 1. 5. An ultrasonic motor according to any one of claims 1 to 4, a power transmission unit that operates integrally with a moving body (140), and an operation based on the operation of the power transmission unit. An electronic device with an ultrasonic motor, comprising: an output unit that operates.