JPH01107675A - ultrasonic motor - Google Patents

Abstract

PURPOSE:To reduce abrasion, by fixing the frictional member of composite plastics material including carbon fiber, pulverulent fluorocarbon resin, and matrix resin, on the surface of contact. CONSTITUTION:So far as an ultrasonic wave motor is concerned, on the surface of a piezoelectric unit 1, a metallic oscillating body 2 is bonded and fixed, and on the contact surface of a mover 4, the frictional member 3 of composite plastics material including carbon fiber, pulverulent fluorocarbon resin, and matrix, at least is firmly fitted. The oscillating body 2 and the frictional member 3 come in contact with each other in the state of pressure applied by a tightening force, and by applying the high-frequency electric-field of resonance frequency to the piezoelectric unit 1, the progressive wave of ultrasonic wave oscillation is generated on the oscillating body 2. By the frictional member 3 coming in contact with the surface of the oscillating body 2, through a frictional force between the member 3 and the oscillating body 2, the mover 4 is driven. As a result, by setting the frictional member 3 of the carbon fiber and the like, stable brake torque can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an ultrasonic motor that utilizes ultrasonic vibrations of a piezoelectric body.

(Prior art) Generally, an ultrasonic motor has a structure in which a vibrating body fixed to a piezoelectric body and a moving body are in pressure contact, and by applying electric power to the piezoelectric body, the piezoelectric body and the vibrating body fixed to the piezoelectric body are It generates a traveling wave of sonic vibration and drives a moving body using frictional force to obtain one mechanical energy. This type of ultrasonic motor will be explained with reference to FIG. In the figure, a vibrating body 2 is adhesively fixed to the surface of a piezoelectric body 1, and a moving body 4 having a friction material 3 fixed to the surface thereof is superimposed on the top surface of the vibrating body 2.

When electric power is applied to the piezoelectric body 1, a traveling wave of ultrasonic vibration in the direction of arrow A is generated in the vibrating body 2. Each mass point of the vibrating body 2 is
It moves in an ellipse as shown by arrow B, with each wave crest moving horizontally in the opposite direction to the direction of the traveling wave, and the trough of the traveling wave moving horizontally in the same direction as the traveling wave. Therefore, the moving body 4 placed on the surface of the vibrating body 2 is in contact with only the top of the wave crest, and is driven horizontally in the direction of arrow C by the frictional force with the vibrating body 2.

The vibrating body 2 and moving body 4 of the ultrasonic motor are made of iron.

Fully flexible materials such as stainless steel and aluminum are used. Furthermore, since the ultrasonic motor has a structure in which the vibrating body 2 and the movable body 4 are in pressurized contact, in order to obtain a large motor output, it is necessary to increase the pressure force or increase the coefficient of friction between the vibrating body 2 and the movable body 4. is necessary.

Conventional ultrasonic motors use rubber or other materials on the contact surfaces of the vibrating body 2 or the movable body 4 in order to reduce wear on the vibrating body 2 and the movable body 4 and obtain stable mechanical energy over a long period of time, as well as to obtain large frictional force. The friction material inside the engineering plastic material is fixed.

(Problems to be Solved by the Invention) However, in the above configuration, I9. When the equipment 3 is used, the friction material 3 is often worn, and abrasion powder adheres to the contact surfaces of the vibrating body 2 and the moving body 4, causing the frictional force between them, that is, the brake torque, to fluctuate over time. was there.

Furthermore, if engineering plastic filled with asbestos fibers or inorganic powder with improved wear resistance is used as the friction material 3, many scratches will occur on the surface of the vibrating body 2, and the braking torque will fluctuate over time. There was a problem. Furthermore, due to the influence of abrasion powder adhering to the vibrating body 2, the resonant frequency of the vibrating body 2 fluctuates over time, resulting in a problem that stable starting performance cannot be obtained.

The present invention solves the above problems and aims to provide a reliable ultrasonic motor with stable performance.

(Means for Solving the Problems) In order to solve the above problems, the present invention uses a composite plastic material consisting of at least carbon fibers, fluorocarbon resin powder, and matrix resin as a friction material.

(Function) With the above configuration, it is possible to obtain a large coefficient of friction, and at the same time, the wear of the friction material itself and the wear of the vibrating body made of iron or stainless steel with which it comes into contact are reduced, and therefore the change in the coefficient of friction over time is reduced. becomes less. As a result, the ultrasonic motor can obtain stable braking torque over a long period of time, and the change in the resonant frequency of the vibrating body over time is also reduced, making it easy to start and providing an ultrasonic motor with excellent long-term reliability. Become.

(Example) FIG. 1 is an enlarged cross-sectional view of the main parts of an ultrasonic motor according to the present invention. A metal vibrating body 2 is adhesively fixed to the surface of the piezoelectric body 1. A friction material 3 made of a composite plastic material containing at least carbon fibers, fluorocarbon resin powder, and a matrix is fixed to the contact surface of the moving body 4.

The vibrating body 2 and the friction material 3 are in contact with each other under pressure due to a fastening force. By applying a high frequency electric field having a resonant frequency to the piezoelectric body 1, a traveling wave of ultrasonic vibration is generated in the vibrating body 2. The friction material 3 that is in contact with the surface of the vibrating body 2 drives the moving body 4 by the frictional force with the vibrating body 2 . When no electric power is input, a holding torque corresponding to the product of the pressing force acting between the vibrating body 2 and the friction material 3 and the friction coefficient acts as a brake torque. By installing the friction material 3 made of a composite plastic material containing carbon fiber and fluorocarbon resin powder, the ultrasonic motor can obtain stable braking torque over a long period of time, and
There is little change in the resonant frequency of the vibrating body over time, and it is possible to start up with good reproducibility and obtain stable driving force. .

There are no special restrictions on carbon fibers; short fibers, long fibers2. Pulp-like fibers, felt-like fibers, woven fibers, etc. can be used.

As the fluorocarbon resin powder, powders of polymers such as tetrafluoroethylene and hexafluoroethylene, copolymers, rubber, and the like can be used.

There are no particular restrictions on the matrix resin; polyimide,
Phenol resins, epoxy resins, engineering plastics, liquid crystal polymers, etc.

Regular plastic can be used.

It is more desirable that the carbon fiber and fluorocarbon resin powder contain 5 weight percent or more of each at the same time.

In addition to the charcoal 74 fibers and fluorocarbon resin powder, other organic or inorganic fine powders may also be added.

There are no restrictions on the shape of the ultrasonic motor, and a disc-shaped ultrasonic motor as shown in FIG. 2 and a ring-shaped ultrasonic motor as shown in FIG. 3 are possible.

Next, the present invention will be explained in more detail with specific examples.6 As shown in Table 1, six types of carbon fibers, five types of fluorocarbon resin powders, and four types of matrix resins were used.
1 mm thickness with uniformly dispersed carbon fibers using 5 different compositions of implementation numbers A to E according to the present invention
A composite plastic friction material sheet and three types of 1 mm thick friction material sheets of Comparative Examples F to H having the same composition as the conventional one and not containing fluorocarbon resin powder or carbon fiber were made, and these were made into 40 mm diameter and 1 mm thick friction material sheets. It was glued onto a stainless steel disk to make a test piece.

In the dynamic friction measurement experiment, the above test piece was rotated at a rotation speed of 30 rpm.
A stainless steel ball with a diameter of 3 m was brought into contact with a load of 200 g at a position 15 mm from the center, and changes in the coefficient of dynamic friction over time were measured. The experimental results are shown in Table 2.

Table 1 Table 2 As is clear from Tables 1 and 2, the composite plastic friction material made of carbon fiber, fluorocarbon resin powder, and matrix resin all have a large friction coefficient of 0.2 or more. Moreover, almost no change in the friction coefficient over time was observed.

On the other hand, the friction coefficients of the friction materials not containing fluorocarbon resin powder, such as Comparative Examples F and G, varied greatly over time. Further, in the case of a friction material that does not contain carbon fibers like Comparative Example H, almost no change in the coefficient of friction over time was observed, but the coefficient of friction was extremely small.

Finally, using the friction materials 3 of Example Nos. A to E used in Example 1 and Comparative Examples F to H, a disk-shaped ultrasonic motor as shown in FIG. 2 was prototyped. In the prototype disc-shaped ultrasonic motor, a stainless steel vibrating body 2 is adhesively fixed to the surface of a piezoelectric body 1, and the composite plastic friction material prototyped in Example 1 is attached to the contact surface of a stainless steel moving body 4. The sheets were each fixed as a friction material 3. The vibrating body 2 and the moving body 4 were pressurized by springs, and the initial brake torque was adjusted to 500 g-zheng. Electrodes are arranged on the piezoelectric body 1 so that four waves of traveling waves are excited in the circumferential direction of the disk, and approximately 70 kl
An electric field having a resonant frequency of lz was applied to drive the moving body 4 at an unloaded rotational speed of 50 rpm.

For each prototype motor, after driving for a predetermined time,
Table 3 shows the results of measuring the presence or absence of restart when the power supply was disconnected, the brake torque after the power supply was disconnected, and the resonance frequency.

Table 3 As is clear from Table 3, in the ultrasonic motors of experiment numbers A to E, which used friction materials consisting of carbon fiber, fluorocarbon resin powder, and matrix resin, the change in brake torque over time was small. There was little change in the resonance frequency over time, and there were no problems with restartability. Furthermore, almost no damage or wear was observed on the vibrating body 2 made of stainless steel, which was in contact with the vibrating body 2.

On the other hand, in the ultrasonic motors of experiment numbers F and G that used friction materials that did not contain fluorocarbon resin powder, the brake torque fluctuated greatly and the resonance frequency also fluctuated, making it impossible for the moving object 4 to restart. There was also.

Furthermore, in the ultrasonic motor of Experiment No. H that used a friction material that did not contain carbon fiber, which is not listed in Table 3, the friction coefficient was too small and the moving body 4 did not rotate.

Previous Example 3 As shown in Table 4, pulp-like PAN-based carbon fibers, tetrafluoroethylene resin powder with an average particle size of 3 μm as the fluorocarbon resin powder, and polyimide as the matrix resin were used, and the content ratios were changed. 6 types of carbon fibers indicated by experiment numbers I to N were uniformly dispersed to a thickness of 1 mm+.
A composite plastic friction material sheet was made, and the same disc-shaped ultrasonic motor as in Example 2 was manufactured using this sheet, and a resonant frequency electric field was applied to drive the ultrasonic motor using the same experimental method as in Example 2. .

Table 4 shows the results of measuring the restartability of each prototype ultrasonic motor when the power source was disconnected and connected after driving for a predetermined period of time, the brake torque after the power source was disconnected, and the resonance frequency.

Table 4 As is clear from Table 4, the carbon fiber content is 5% by weight.
Above, and in the experiment number using friction material 3 with a composition containing fluorocarbon resin powder of 5% by weight or more, L, M
All of these ultrasonic motors showed small changes in brake torque over time, small changes in resonance frequency over time, and no problems with restartability.

On the other hand, the ultrasonic motors of experiment numbers I and J, in which the content of fluorocarbon resin powder was 2% by weight or less, had a large change in brake torque over time, and also had a large change in resonance frequency, resulting in failure to restart. Ta. The ultrasonic motor of Experiment No. N, which contained only fluorocarbon resin powder without carbon fiber, stopped rotating when a brake torque of more than 200 g-am was applied, and a large output could not be obtained. The wear of Material 3 was large.

A raw felt was impregnated with a phenol resin solution in which carbon fibers and fluorocarbon resin powder were uniformly dispersed, and after pre-drying, compression molding was performed to obtain a composite plastic friction material sheet with a thickness of 111111. Using this as the friction material 3,
A disk-shaped ultrasonic motor as shown in FIG. 2 was prototyped using the same method as in Example 2.

A composite plastic with a thickness of 1 m is obtained by impregnating a laminable carbon fiber plain-woven fabric with a polyimide solution in which fine fluorocarbon resin powder with an average particle size of 1 μm is uniformly dispersed, and after pre-drying, compression molding is performed. The gamma vibration material sheet is fl). Using this as an lf scrubbing device, a disk-shaped ultrasonic motor as shown in FIG. 2 was prototyped in the same manner as in Example 2.

In both the ultrasonic motors of Example 4 and Example 5, the brake 1-lux was 500 g-cn at the initial stage and 5 hours later.
30 g-an, and its change over time was small. Also, the resonant frequency is 70.8 kl, respectively.
Hi.

70.6 k Ilz, there was almost no change between the initial stage and after 5 hours, and there was no problem in restartability.

In addition, the vibrating body 2 made of stainless steel, which was the contacting material, was irreparable and almost no wear was observed.

(Effects of the Invention) As explained above, by fixing a friction material made of a composite plastic material containing at least carbon fiber, fluorocarbon resin powder, and matrix resin to one contact surface of a vibrating body or a moving body, wear and tear can be reduced. It is possible to obtain an extremely reliable ultrasonic motor that has stable starting performance with little change in brake torque over time, and little change over time in the resonant frequency of the vibrating body.

[Brief explanation of the drawing]

FIG. 1 is an enlarged cross-sectional view of essential parts showing the configuration of an ultrasonic motor according to the present invention, FIGS. 2 and 3 are perspective cross-sectional views of the ultrasonic motor according to the present invention, and FIG. 4 illustrates the principle of the ultrasonic motor. FIG. 1... Piezoelectric body, 2... Vibrating body, 3... Friction material, 4... Moving body. Patent applicant: Matsushita Electric Industrial Co., Ltd. Figure 1 1... Piezoelectric body 2... Handling 3... *Morimura 4... Moving seat Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] An ultrasonic motor that brings a moving object into pressure contact with an ultrasonic vibrating body that generates a traveling wave on its surface and drives the moving object using frictional force, the ultrasonic motor containing at least carbon fiber, fluorocarbon resin powder, and matrix resin. An ultrasonic motor characterized in that a friction material made of a composite plastic material is fixed to the contact surface of the vibrating body or moving body.