JPH0255586A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To lengthen the service life and to eliminate noise by placing a multi- layer fiber reinforced plastic in which the content of fiber is highest at the surface layer and decreases toward the inner layer between a vibrator and a moving body. CONSTITUTION:An ultrasonic motor comprises vibrators 1, 6, a piezoelectric body adhered to the underface thereof, moving bodies 2, 5, and the like. A multi-layer fiber reinforced plastic structure 3 in which the content of fiber is highest at the surface layer and decreases toward the inner layer is placed between the moving body 2 and the vibrator 1. Since the vibrator 1 and the moving body 2 can be contacted with uniform pressure, a uniform friction contacting state can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an ultrasonic motor that is driven using ultrasonic vibrations produced by a piezoelectric body.

Conventional technology An example of an ultrasonic motor is one in which a moving body is brought into pressure contact with a vibrating body that generates traveling waves using a piezoelectric body.
The moving body is driven through the frictional force between the vibrating body and the moving body in a pressurized contact state. Therefore, the state of frictional contact between the vibrating body and the palpitation increases the output, efficiency, and
It is one of the extremely important factors that determines the characteristics of life. , Conventional ultrasonic motors have a friction material with a large friction coefficient called a slider interposed between the vibrating body and the moving body, but the specific structure of the slider and its effects are not well known. Therefore, there is no ultrasonic motor that maintains a uniform frictional contact state between the vibrating body and the moving body and has a stable and long life by bringing the vibrating body and the moving body into pressurized contact with uniform pressure. is the current situation.

Problems to be Solved by the Invention In an ultrasonic motor that utilizes frictional force when a vibrating body and a moving body are in pressurized contact, it is necessary to The material surface needs to be made of a material with a high modulus of elasticity so as not to attenuate this amplitude. However, when the friction material is made of a material with a high modulus of elasticity, in order to bring the vibrating body and the moving body into pressure contact with uniform pressure and to follow the amplitude of the micron order, the surface of the vibrating body and the surface of the friction material must be It was necessary to process it with ultra precision.

If the machining accuracy of the vibrating body surface and friction material surface is poor,
Since there is no pressurized contact with uniform pressure, the amplitude of the vibrating body cannot be efficiently transmitted when the motor is driven, resulting in a decrease in motor efficiency and stable motor characteristics such as fluctuations in motor rotation speed over time. There was a problem in that it was not possible to obtain

Furthermore, if the machining accuracy of the vibrating body surface and the friction material surface is poor, the frictional contact state becomes non-uniform, and there is also the problem that noise is generated when the motor is driven.

The present invention provides an ultrasonic motor that does not require ultra-precision machining of the vibrating body surface and the friction material surface, can obtain a uniform pressurized contact state, does not cause deterioration of motor characteristics, has a long life, and is noiseless. The purpose is to

Means for solving the problem Between a vibrating body that generates traveling waves using a piezoelectric body and a moving body,
A fiber-reinforced plastic is interposed that is fixed to a moving body and has a multilayer structure in which the surface layer has the highest fiber content and the fiber content decreases toward the inner layer in the thickness direction.

Effect The above structure can absorb unevenness and undulations on the surface of the fiber-reinforced plastic layer of the surface layer or on the surface of the vibrating body. Therefore, it is possible to uniformly process the vibrating body surface and the friction material surface without the need for ultra-precision machining. A pressure contact state can be obtained.

Further, by providing a fiber-reinforced plastic layer with a high fiber content in the surface layer, the amount of wear of the friction material can be significantly reduced even after long-term driving.

Furthermore, by having a multilayer structure with varying fiber content, the vibrating body and the moving body can be brought into pressure contact with uniform pressure, and therefore a uniform frictional contact state can be obtained.
No noise is generated even when the motor is driven.

Example An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a sectional view of the main components of the ultrasonic motor of the present invention. Here, ■ is a vibrating body, and a piezoelectric body (not shown) is adhesively fixed to the lower surface of this vibrating body 1. Furthermore, 2
is a moving object, and as a feature of the present invention, this moving object 2
and the vibrating body 1, the surface layer has the highest fiber content,
A fiber-reinforced plastic 3 having a multilayer structure in which the fiber content decreases toward the inner layer in the thickness direction is interposed.

Next, the present invention will be explained in more detail with reference to specific examples. In this embodiment, a friction material 3 made of fiber-reinforced plastic having a multilayer structure is provided between the vibrating body 1 and the moving body 2.
For convenience, we used a method of adhering and fixing a friction material 3 made of fiber-reinforced plastic with a multilayer structure to the surface of the moving body 2 and pressing it against the vibrating body 1 using spring pressure. It is not limited. Further, although stainless steel is used as the vibrating body 1, the material is not limited to this, and the vibrating body 1 can be made of any material that does not absorb the vibrations of the piezoelectric body and has a large frictional force with the friction material 3. good.

Example 1 Two types of carbon fiber plain woven fabrics (manufactured by Toho Rayon Co., Ltd., Hesphite) with a basis weight of 95 glrR and 200 g/I were coated with a bismaleimide triazine resin (manufactured by Mitsubishi Gas Chemical Co., Ltd., BT2112) that imparted flexibility. ) was impregnated into a semi-cured state. Next, out of this semi-cured plain weave fabric, a fabric weight of 95 g
g/n? Three sheets of plain woven fabric were laminated. Furthermore, this laminate was molded under heat and pressure via a spacer to produce a fiber-reinforced plastic in which the surface layer and the inner layer had different fiber contents of carbon fibers.

In the method for manufacturing a friction material for an ultrasonic motor according to the above embodiment, two types of plain woven fabrics having different basis weights of carbon fibers are laminated, so that the fiber content of carbon fibers is different between the surface layer and the inner layer. A fiber-reinforced plastic with a two-layer structure was created, and the surface was It is possible to manufacture a friction material made of fiber-reinforced Bugo 7 Sudik having a multilayer structure in which the fiber content of each layer is highest and the fiber content decreases toward the inner layer in the thickness direction.

Although woven fabric was used as the carbon fiber in the above examples, the form of the fiber material in the manufacturing method of the present invention is not limited to woven fabric. It can be used as long fiber or short fiber, and fibers of the following types can be used together or in any combination.

Furthermore, in the handbook example, a flexible hismaleimide-I-sulfur resin was used as the fiber binding material for the carbon fibers, but as this fiber binding material, the same resin was However, it is also possible to arbitrarily combine a plurality of fiber binding materials without changing the resin used in each layer.

Next, when using the fiber-reinforced plastic obtained in the above example as a friction material for an ultrasonic motor, the two surface parts are surface-polished using a cylindrical grinder, and the carbon fiber As shown in FIG. 2, a friction material 4 having a two-layer structure due to different fiber contents of
A disk-type ultrasonic motor with a diameter of 40 mm was produced by crimping between the vibrating body 0 and the moving body 5, each of which had a piezoelectric body 7 adhered to its bottom surface, using a vibrating body 0 (not shown).

When this disk-type ultrasonic motor was driven, no noise was generated (1100gf-cm large starting torque and 500gf-cm).
At the same time, a no-load rotation speed of 00 rpm was obtained, and at the same time, 45%
motor efficiency was obtained.

In addition, when a load of 400 gf-cm was applied in the opposite direction to the rotation direction and the motor was rotated at a rotation speed of 300 rpm, no decrease in rotation speed was observed over time, and the motor maintained stable performance even after 5 million rotations. Indicated.

Furthermore, when we measured the wear reduction thickness of the friction material after 5 million revolutions, it was very small at 35μrT1, and even after 5 million revolutions, there was almost no change from the initial state in both starting torque and no-load rotation speed (stable motor performance. was maintained.

For comparison, three sheets of carbon fiber plain woven fabric with an i content of 200 g/- were laminated to produce fiber reinforced plastic in the same manner as in Example 1, and this was used as a friction material. After polishing the friction material in the same manner as in Embodiment 1, a disk-type ultrasonic motor was manufactured and driven. Noise was generated at the beginning, and both the starting torque and the no-load rotation speed were smaller than those in Example 1. At the same time, a motor efficiency of only 35% was obtained.Furthermore, when operated for a long time, the starting torque,
The range of change from the initial state in both the no-load rotational speed was larger than in Example 1.

Example 2 Polytetrafluoroethylene powder (manufactured by Daikin Industries, Ltd.,
Polyflon) and milled carbon fiber (manufactured by Mitsubishi Rayon Co., Ltd., Pyrofil) are uniformly mixed, and the fiber content of the carbon fiber is 25% and 10% by weight2.
Various mixed powders were prepared. Next, 20% by weight of a mixed powder with a carbon fiber content of 25%, 40% by weight of a mixed powder with a carbon fiber content of 10%, and 40% by weight of a polytetrafluoroethylene powder were sequentially added in this order. After filling into the mold, 500 kg/co? Pressure molding was performed at a pressure of . Furthermore, by firing this molded product at 380° C., fiber reinforced plastics having different carbon fiber contents in the thickness direction were produced.

In the method for manufacturing a friction material for an ultrasonic motor according to the two-leg example, polytetrafluoroethylene powder mixtures having different carbon fiber fiber contents are sequentially filled in descending order of carbon fiber fiber content, and then processed. By compression molding, fiber-reinforced plastics with different fiber contents of carbon fibers in the thickness direction were produced. By filling the products one by one and then press-molding them,
It is possible to produce a friction material made of fiber-reinforced plastic that has a multilayer structure in which the surface layer has the highest fiber content and the fiber content decreases toward the inner layer in the thickness direction.

In the above examples, milled fibers were used as carbon fibers, but in the manufacturing method of the present invention, the form of the fiber material is not limited to milled fibers (pulp or short fibers can also be used). I can do it,
Moreover, the above-mentioned types of fibers can be used together or in any combination.

Next, when using the fiber-reinforced plastic obtained in the above example as a friction material for an ultrasonic motor, the surface part is ground with a cylindrical grinder, and the carbon fiber content is reduced in the thickness direction. As shown in FIG. 2, a friction material 4 having a three-layer structure is crimped between a vibrating body 6 and a moving body 5 on which a piezoelectric body 7 is bonded on the bottom surface using a spring (not shown). A disc-type ultrasonic motor with a diameter of 40 mm was manufactured.

When this disk-type ultrasonic motor was driven, there was no noise and a large starting torque of 1000g100O was achieved.
At the same time, a no-load rotation speed of 5 Orpm was obtained, and at the same time, 43%
motor efficiency was obtained.

Furthermore, when a load of 400 gf-Cm was applied in the opposite direction to the rotational direction and the motor was rotated at a rotation speed of 300 rpm, no decrease in rotational speed was observed over time, and stable motor performance was exhibited even after 5 million rotations.

Furthermore, when we measured the wear reduction thickness of the friction material after 5 million rotations, it was extremely small at 15 μm.Even after 5 million rotations, there was almost no change in starting torque and no-load rotation speed from the initial stage, indicating stable motor performance. was maintained.

For comparison, a mixed powder with a carbon fiber content of 25% was pressure-molded, and then a fiber-reinforced plastic was produced in the same manner as in Example 2, and this was used as a friction material. After polishing the friction material, a disk-type ultrasonic motor was manufactured and when it was driven, noise was generated at the beginning, and both the starting torque and the no-load rotation speed were small compared to Example 1. At the same time, only 33% motor efficiency was obtained. Furthermore, when operating for a long time, the starting torque,
The range of change from the initial state in both the no-load rotational speed was larger than in Example 1.

In the above two examples, carbon fibers were used as the reinforcing fibers in the fiber-reinforced plastics, but the invention is not limited to this. In addition, it goes without saying that inorganic fibers and heat-resistant organic fibers may be used together, and it is also optional to combine inorganic fibers and heat-resistant organic fibers. be.

Furthermore, in the above two examples, the flexibility-imparting bismaleimide triazine resin and the polytetrafluoroethylene resin were used as the fiber binding material in the fiber-reinforced plastic, but they are not limited to these (for example, polyimide Resin, polyamideimide resin, bismaleimide
Resins with high heat resistance such as triazine resin, phenol resin, and epoxy resin can be used alone or in combination.

Effects of the Invention According to the present invention, it is possible to absorb the unevenness and undulations on the fiber-reinforced plus rack surface of the surface layer with a high fiber content or on the surface of the vibrating body, and to maintain a uniform frictional contact state between the vibrating body and the moving body. At the same time, the wear amount of the friction material is extremely small even after long-term operation, so there is no need for ultra-precision machining of the vibrating body surface and the friction material surface, and a uniform pressurized contact state can be obtained. It is possible to obtain a noiseless ultrasonic motor with a long life and no deterioration of characteristics.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the main components of an ultrasonic motor according to an embodiment of the present invention, and FIG. 2 is an exploded partial cross-sectional view of the main components of a disc-type ultrasonic motor according to the same embodiment. FIG. 1.6... Vibrating body, 2,5... Moving body 3... Multilayer fiber reinforced plastic friction material, 4
...Friction material, 7...Piezoelectric material.

Claims (1)

[Claims] In an ultrasonic motor, a vibrating body that generates a traveling wave by a piezoelectric body and a moving body are brought into pressurized contact, and the moving body is driven by the traveling wave through a frictional force acting between the vibrating body and the moving body,
A fiber-reinforced plastic is interposed between the vibrating body and the moving body and has a multilayer structure in which the surface layer has the highest fiber content and the inner layer in the thickness direction has a lower fiber content. An ultrasonic motor characterized by: