JPS63302773A - Ultrasonic wave motor - Google Patents

Abstract

PURPOSE:To avoid noise and increase a driving force, by using resin material for a moving unit, and by placing lubricant on the surface between the moving unit and a stationary unit in contact with each other. CONSTITUTION:An ultrasonic wave motor is composed of a stationary unit 2 provided with a piezoelectric unit 1, in pressure contact with a moving unit 3 made of resin material. In this case, on the field surface between the stationary unit 2 and the moving unit 3 in contact with each other, lubricant 4 is placed. As the resin material of the moving unit 3, phenol resin, fluororesin, or the like is used, and in order to increase the strength, glass fiber, carbon fiber, or the like is included in the resin. As the lubricant 4, liquid lubricant or semi-solid lubricant is used. As a result, even if the lubricant 4 to reduce friction is placed on the surface between the stationary unit 2 and the moving unit 3 in contact with each other, a great driving force can be obtained and a device can be stably driven for a long time.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a motor that is driven by generating ultrasonic vibrations consisting of progressive vibration waves using a piezoelectric body.

(Prior Art) In an ultrasonic motor using a progressive vibration wave method, a fixed body and a movable body are pressed against each other in surface contact, and a piezoelectric body is attached to the fixed body. By applying a voltage to both ends of the piezoelectric material with a phase difference, minute vibrations consisting of progressive vibration waves are generated. The minute vibrations are excited by the fixed body and transmitted to the moving body,
The movable body is moved through the frictional force caused by the contact between the fixed body and the movable body. The contact surface of the stationary body with the moving body.

By applying a voltage, a surface wave consisting of a progressive vibration wave is generated, and when one point on the surface is taken, it moves while drawing an elliptical locus, and the moving body is driven by its transverse velocity component. Therefore, in order to reliably transmit the lateral movement of the stationary body to the contact surface of the stationary body and prevent slippage, it is recommended that the moving body use a material with a high coefficient of friction, such as rubber, on the contact surface of the stationary body. considered desirable.

Therefore, in order to increase the friction between a fixed body called a slider and a movable body made of metal, a method of attaching a thin rubber material to the movable body has been considered.

Alternatively, constructing a moving body using a single metal material is also being considered.

And since this type of motor does not require windings compared to conventional electromagnetic motors, it can not only be manufactured in a smaller size, but also
Rotating machines that rotate at low speed, have high torque, or have little inertia are being put into practical use as automatic focus adjustment or automatic aperture mechanisms for lenses in optical machines such as cameras.

(Problems to be Solved by the Invention) If a moving body is constructed using a single metal material, noise will be generated during driving, wear will be severe due to friction with a fixed body, and problems such as baking and development will occur. There was a problem in that it was difficult to maintain performance as a motor.

On the other hand, the method of using a material with a high coefficient of friction such as rubber on the contact surface between the moving body and the fixed body and attaching it to the moving body made of metal has the problem of severe wear due to friction and difficulty in maintaining performance. there were.

The structure of the moving body as described above is a method in which all or most of the moving body is made of a metal material, and the moving body is heavier than a resin material. Therefore, the responsiveness to electrical signals when starting to rotate from a stopped state or when stopping from rotating is affected by an inertial force that depends on the weight of the moving object, so it will start rotating or stop by the weight of the moving object. There was also the problem that it was too late.

The present invention solves the conventional problems as described above, and aims to provide an ultrasonic motor that does not generate noise when the motor is driven. In addition, the present invention has a large driving force generated by pressurized contact between the fixed body of the motor and the movable body, and the amount of wear caused by friction of the contact surface when the motor is driven is minimized, resulting in stable operation for a long time. The purpose of this invention is to provide an ultrasonic motor that can maintain its performance.

Another object of the present invention is to provide a high-performance ultrasonic motor that can be started and stopped quickly in response to an electric signal.

(Means for Solving the Problems) In order to achieve the above object, one aspect of the present invention is to bring a movable body into pressure contact with a fixed body having a piezoelectric body mounted thereon.

In an ultrasonic motor in which the movable body moves by minute vibrations made of progressive vibration waves of the piezoelectric body.

The movable body is made of a resin material, and a lubricant is present at the contact interface between the fixed body and the movable body. Further, the lubricant of the present invention includes liquid lubricant, semi-solid lubricant (grease), etc., and the rotating shaft of the moving body may be made of other than resin material.

Furthermore, the moving body of the present invention may be made of a resin material containing a ferrite magnet, and the fixed body may be made of a magnetic material.

(Function) Since the movable body is made of resin material, the movable body is lighter compared to the case where the movable body is made of conventional metal materials.As an example, we will discuss the responsiveness when the ultrasonic motor stops. explain. The moving body of the ultrasonic motor moves at a certain constant speed V by inputting an electric signal to the piezoelectric body and by minute vibrations made of progressive vibration waves of the fixed body.

So 1. When the electrical input is cut off, the moving body has a kinetic energy of ■v2 (m is the mass of the moving body). On the other hand, due to the structure of the ultrasonic motor, the movable body is always in contact with the fixed body with a certain pressure, so when the electrical input is turned off, the contact surface
A frictional force f acts on the moving body to try to stop it, so rav”=fl. Here, Q is the distance it moves after cutting off the electrical input. The frictional force f acts on the fixed body and It is expressed as the product of the contact force between moving bodies and the coefficient of friction between their contact surfaces, and it is thought that there is an optimal value that is approximately constant depending on the shape of the ultrasonic motor.On the other hand, if the moving body is made of resin By making the mass lighter, the kinetic energy becomes smaller by the lighter mass. Therefore, the distance Q traveled after cutting off the electrical input becomes shorter, and the motor stops faster in response to the electrical signal. .In the case of starting, the effect is almost the same as in the case of stopping, and by using a resin material for the moving body, the starting performance becomes faster.

Furthermore, by providing a lubricant at the contact interface between the fixed body and the movable body, not only does noise not occur when the motor is driven, but also driving force is generated through appropriate pressurized contact between the fixed body and the movable body of the motor. was completed. As a result, it is possible to obtain a practically usable ultrasonic motor that can stably maintain performance for a long period of time with little wear caused by friction of the contact surfaces when the motor is driven.

(Example) The basic configuration of the ultrasonic motor of the present invention is shown in FIG. 1. The ultrasonic motor has a configuration in which a movable body 3 made of a resin material is pressed into contact with a fixed body 2 on which a piezoelectric body 1 is attached. . Fixed body 2
As an actual application example of the present invention, the lubricant 4 is present at the contact interface between the moving body 3 and the moving body 3. figure)
can be mentioned.

As the piezoelectric body, a three-component piezoelectric ceramic of lead oxide, lead titanate, and lead zirconate is used, and as the fixed body,
We used materials such as stainless steel, steel, and aluminum that can efficiently transmit vibrations to the moving body. Resin materials for moving objects include grill resin, phenol resin, furan resin, urea resin, melamine resin, xylene resin, epoxy resin, unsaturated polyester resin, and vinyl chloride resin.

Polyamide resin, polystyrene resin, polyamideimide resin, polyimide resin, polysulfone resin.

Polyester resin, polyacetal resin, polyphenylene oxide resin, polyphenylene sulfide resin, polycarbonate resin, fluororesin, etc. can be used. Furthermore, in order to reinforce the strength,
Glass fiber, carbon fiber.

Wood flour 2 quartz powder as a filler or extender for fibrous materials such as aromatic polyamide fibers, pulp, and asbestos.

Silica sand powder, carbon black, iron powder, alumina.

It may be necessary to adjust the hardness of the resin by adding mica, silica, talc, molybdenum sulfide powder, calcium carbonate, or barium sulfate. In other words, in order to efficiently transmit the minute vibrations of a fixed body, it is soft and absorbs all the vibrations.

Since the moving body is not driven at all, it is necessary to modify the soft resin so that it has a certain degree of hardness. As the lubricant, either a liquid lubricant or a semi-solid lubricant can be used. Liquid lubricants include silicone oil,
Synthetic lubricating oils such as polyalkylene gelicols, diester and fluorocarbon oils, mineral oils such as turbine oil, dynamo oil, spindle oil, machine oil and cylinder oil are used. Semi-solid lubricants (grease) use the above-mentioned liquid lubricant as a base oil, and contain thickeners such as metal soap, fillers such as graphite and molybdenum sulfide, and antioxidants and extreme pressure additives. The one synthesized by adding the following additives is used.

Hereinafter, a specific example will be described in which the present invention is applied to a disc-shaped ultrasonic motor. As the resin material for the movable body 5, acrylic resin was selected and cut into the shape shown in FIG.
Silicone oil was applied as a lubricant to the contact surface 8 of the moving body 5. In order to bring the fixed body and the movable body into pressurized contact with each other, a coil spring was used to create a pressing force of 2 g/01''.

The motor diameter is 40+am, and the weight of the moving object is approximately 9g.
It became. When this motor was driven with an input power of approximately 3W, there was no noise at all, and the starting torque was 400 gf.
am, the no-load rotation speed was 70 rpm, and sufficient motor performance could be obtained. Further, when the device was continuously rotated for 24 hours, almost no wear was observed on the contact surfaces between the movable body and the fixed body, and the device was driven stably. Until now, it has been thought that ultrasonic motors can obtain large driving force (starting torque) by increasing the friction of the contact surfaces. However, as in the present invention, M<should be
Even if a lubricant that reduces friction is present on the contact surface between the stationary and moving objects, a large driving force can be obtained.
And it can be driven stably for a long time.

Similar good results were obtained using the other lubricants mentioned above in addition to the silicone oil used here.

Furthermore, the responsiveness to electrical signals depends on the weight of the moving body.Compared to the weight of the moving body produced in the present invention, which weighs 9 g, the response to the electric signal was 55 g when similarly produced from stainless steel. When we measured the rising speed of both of them, it was approximately 20m5ec for stainless steel material, and approximately 2 to 3cmsees for acrylic resin material.By composing the moving body with resin material, it was found that the response speed was extremely fast. A sonic motor was obtained. Further, as a configuration of the moving body, the rotating shaft 9 was made of a metal material to have mechanical strength for power transmission, and the other moving body part 10 was made of a resin material. Figures (a), (b))
.

In this case, the weight of the moving body increases compared to a configuration made only of resin, but the responsiveness to electrical signals is
3 + m5ec, showing almost the same value.

This means that the moment of inertia for a rotating body is ■=Σl
This is thought to be because the center part had almost no effect on the inertial force since it was expressed as 1r2. As described above, the present invention does not limit the one-rotation shaft 9 to be made of a resin material, and the one-rotation shaft can be arbitrarily selected as appropriate depending on the intended use of the ultrasonic motor.

In the annular ultrasonic motor shown in Figure 3, the movable body is made of a resin material containing ferrite magnets, etc., and the movable body is pressurized. The ultrasonic motor of the present invention was constructed by providing lubricating oil on the contact surface between the body and the moving body.

Furthermore, regarding the one-ring type, it was also possible to adopt a configuration similar to the disk type shown in FIG.

(Effects of the Invention) In the present invention, a resin material is used for the movable body and a lubricant is interposed on the contact surface between the movable body and the fixed body, so noise generated when the motor is driven due to friction between the two is generated. It has a large driving force and can maintain stable performance for a long time.

Furthermore, the present invention provides an ultrasonic motor that is lightweight in weight by using a resin material for the movable body, and is therefore quick in starting and stopping responsiveness to electric signals of the motor.

Furthermore, in the present invention, there is no wear powder of the friction material.

Stable starting/stopping responses can be achieved after long periods of driving and after repeated stopping and driving.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the basic configuration of the ultrasonic motor of the present invention, FIG. 2 is a perspective view showing the configuration of a disk-shaped ultrasonic motor, and FIG. 3 is a one-ring type ultrasonic motor. FIG. 4 is a sectional view of a moving body of a one-disk type ultrasonic motor, and FIG. 5 is a sectional view showing the configuration of an annular ultrasonic motor. 1.6.6', 13...piezoelectric body, 2,7°7', 1
2... Fixed body, 3.5.5', 11... Moving body, 4... Lubricant, 8.8'... Contact surface,
9... Rotating shaft, 10... Moving body section, 14... Felt, 15... Base, 16... Bearing. FIG. 14 Electric body 2-rEJ, body 3-#1 body 4-0. Diagram 2 5. - Rei F1 strain 609. Piezoelectric body 7-solid body 8, -holding II! Surface Fig. 3 5' - Rei 6' - 9 Piezoelectric body 8' - Contact surface 7' - Fixed body Fig. 4 (a) (b) 9 - Axis of rotation io = Rei vJ body Fig. 5 11, ++ Removing body 12, -, solid 7 body 13-0 piezoelectric body 14 + felt 15-base white 16-, bare)ge

Claims (4)

[Claims] (1) In an ultrasonic motor that brings a movable body into pressure contact with a fixed body equipped with a piezoelectric body and moves from the movable body by minute vibrations made of progressive vibration waves of the piezoelectric body, the movable body An ultrasonic motor made of a resin material, and characterized in that a lubricant is present at a contact interface between the fixed body and the movable body. (2) The ultrasonic motor according to claim (1), wherein the lubricant is either a liquid lubricant or a semi-solid lubricant (grease). (3) The ultrasonic motor according to claim (1), wherein the rotating shaft of the movable body is made of a material other than a resin material. (4) The ultrasonic motor according to claim (1), wherein the moving body is made of a resin material containing a ferrite magnet, and the fixed body is made of a magnetic material.