JPS63257477A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To start the title apparatus stably by using a friction material composed of plastic materials containing a metallic soap in the contact surface. CONSTITUTION:An ultrasonic motor is composed of a piezoelectric body 1, a metal vibrator 2 bonded and fixed to the surface of said body 1, a moving body 3, and a friction material 4 fixed to said body 3. In this case, said friction material 4 is composed of a metallic soap, for example, plastics containing stearic acid, ricinoleic acid or the like. Then, the vibrator 2 and the friction material 4 are pressurized and contacted by a fastening force. Thus, when a high-frequency electric field with resonance frequency is inputted to the piezoelectric body 1, a progressive wave is generated in the piezoelectric body 1 and the vibrator 2. As a result, the moving body 3 is integrally driven to rotation by said friction material 4.

Description

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

Conventional technology Generally, an ultrasonic motor has a configuration in which a vibrating body to which a piezoelectric body is fixed is in pressure contact with a moving body, and an electric input to the piezoelectric body generates an ultrasonic wave between the piezoelectric body and the vibrating body as shown in Fig. 4. The principle is to generate a traveling wave of sonic vibration and drive the moving body by the frictional force with the moving body to obtain mechanical energy. In FIG. 4, 1 is a piezoelectric body, and a vibrating body 2 is adhesively fixed to the surface of the piezoelectric body. 3 is a moving body, and a friction material 4 is fixed to the moving body 3. By applying electrical input to the piezoelectric body 1, a traveling wave in the input direction of ultrasonic vibration is generated in the vibrating body 2. Each mass point of the vibrating body 2 moves in an ellipse as shown by B, and each wave crest has the property of moving laterally in the opposite direction to the direction of the traveling wave. However, the trough portion of the traveling wave has the property of moving laterally in the same direction as the traveling wave.

Therefore, an object placed on the surface of the vibrating body contacts only the top of the wave and is driven laterally in the C direction by the frictional force with the vibrating body. In such an ultrasonic motor, it has been proposed to use a rubber material or a plastic material as a friction material, and the moving body and the vibrating body are pressurized by a fastening force.

Problems to be Solved by the Invention When the friction material is made of ordinary rubber or plastic material, as the drive time of the ultrasonic motor increases, the holding torque in the rotating direction of the moving object ( In other words, there is the problem that the brake torque (brake torque) increases, making it impossible to obtain a motor with a stable braking force.Furthermore, since the resonant frequency also changes, there is a problem that stable rotation cannot be obtained.

Means for solving the problem: A vibrating body is fixed to the contact surface of at least one of the moving body,
A friction material made of a plastic material containing at least metal soap is disposed.

Since there is little change in the operating holding torque over time, stable braking characteristics can be obtained over a long period of time when the motor is repeatedly driven and stopped. Furthermore, there is little variation in the applied co-grip frequency, allowing stable startup.

Embodiment FIG. 1 is an enlarged cross-sectional view of the main components of an ultrasonic motor according to the present invention. 1 is a piezoelectric body, and a metal vibrating body 2 is adhesively fixed to the surface of the piezoelectric body. 3 is a moving body, and a friction material 4 made of plastic containing metal soap is fixed to the moving body 3. The vibrating body 2 and the friction material 4 are brought into pressure contact by a fastening force. By inputting a high frequency electric field having a resonant frequency to the piezoelectric body 1, a traveling wave of ultrasonic vibration is generated in the piezoelectric body 1 and the vibration body 2. The friction material 4 in contact with the surface of the vibrating body is driven integrally with the moving body 3 by the frictional force with the vibrating body 2. When no electric power is input, a holding torque, that is, a braking force corresponding to the product of the pressing force acting between the vibrating body and the friction material and the friction coefficient is generated. By using a friction material made of plastic containing metal soap, the holding torque changes little over time, and even if the motor is repeatedly driven and stopped, stable braking torque can be obtained for a long period of time. Furthermore, there is little variation in the applied resonant frequency, allowing for highly reproducible startup and stable rotation.

Metal soaps include lead salts such as stearic acid, phosphorous acid, heptathenic acid, lauric acid, and tin lead.

aluminum salt, zinc salt, cadmium salt, barium salt,
Strontium salts, calcium salts, magnesium salts, lithium salts, and non-metallic acids can be used.

There are no particular restrictions on the plastic, but polyimide, polyamideimide, polyamide, polyester, phenol resin, epoxy resin, high molecular weight polyethylene, bismaleimide resin, triazine resin, polyether sulfone, polyamino bismaleimide, polyoxybenzylene resin, etc. Ordinary plastics and engineering glass such as arylate and polyether sulfone, flexible rubber materials such as polyurethane and synthetic rubber, and composites made by combining these plastics and rubber materials with inorganic and organic powders and fibers. Plastic etc. can be used.

Next, the present invention will be explained in more detail with reference to specific examples.

Example 1 50 parts by weight of bismaleimide triazine resin and nitrile
Each plastic composition shown in Table 1, consisting of 20 parts by weight of butadiene rubber, 30 parts by weight of para-type aromatic polyamide fiber, and 6 parts by weight of metal soap, was uniformly kneaded to form a sheet having a thickness of SOO μm. Using each sheet as a friction material, a disc-type ultrasonic motor with a diameter of 50 mm and a thickness of 8 mA as shown in FIG. 2 was constructed. In FIG. 2, 1 is a piezoelectric body, and a stainless steel moving body 2 is adhesively fixed to the surface of the piezoelectric body. 3 is a moving body made of iron,
The friction material 4 is adhesively fixed.

The vibrating body and the moving body are pressurized by tightening screws. The electrodes are arranged so that four traveling waves are excited in the circumferential direction of the disk, and the resonance frequency is 70 KHz.

Applying a voltage of 40V to the moving body at an initial rotation speed of 300r
It was rotated and driven at pm.

For each motor that made up each friction material, after driving for a predetermined period of time, we measured whether or not it restarted when the power input was turned off and on, and the brake torque after the power was turned off.The results are shown in Table 1. show.

As is clear from Table 1, when the friction material is made of a plastic material containing metal soap, the change in brake torque over time is small for all motors. Further, no problem occurred with respect to restartability of the moving object.

On the other hand, when no metal soap was contained (composition number 1), the brake torque varied greatly and the moving body did not restart.

Example 2 Each plastic composition shown in Table 2, consisting of 100 parts by weight of polyamide-imide resin, 60 parts by weight of mica powder, and 3 parts by weight of metal soap, was uniformly kneaded to a thickness of 5 parts by weight.
A sheet of 00 μm was molded. An ultrasonic motor as shown in FIG. 3 was constructed using each sheet as a friction material. In FIG. 3, 1 is a piezoelectric body, and an iron vibrating body 2 is adhesively fixed to the surface of the piezoelectric body. The friction material 4 is adhesively fixed to the surface of the iron vibrating body 2. 3 is an aluminum moving body, and the vibrating body portion and the moving body portion are pressurized by tightening screws.

For each motor fully configured with each friction material, the motor was driven in the same manner as in Example 1, and after driving for a predetermined time, whether or not it restarted when the power input was turned off and on, and after the power was turned off. Table 2 shows the results of measuring the brake torque.

C''-L1 margin) As is clear from Table 2, when the friction hammer is constructed of a plastic material containing metal soap, the change in brake torque over time is small for all motors. Further, no problem occurred with respect to restartability of the moving object.

On the other hand, when no metal soap was contained (composition number 7), the brake torque changed significantly and the moving body did not restart.

Effects of the Invention By configuring a friction material made of a plastic material containing at least metal soap and fixed to the contact surface of at least one of the vibrating body and the moving body, changes in holding torque over time are reduced, and the motor is driven and stopped. In the repetition of
It is possible to obtain stable braking characteristics for a long period of time. Furthermore, stable startup will be possible.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the main components of the ultrasonic motor of the present invention;
FIGS. 2 and 3 are block diagrams of an ultrasonic motor according to an embodiment, and FIG. 4 is a block diagram of main parts showing the principle of the ultrasonic motor. 1... Piezoelectric body, 2... Vibrating body, 3...
...Moving object, 4...Friction material. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 113

Claims (1)

[Claims] In an ultrasonic motor, an ultrasonic vibrating body that generates a traveling wave on its surface and a moving body are in pressure contact with each other, and the vibrating body drives the moving body through frictional force between the two. An ultrasonic motor having a friction material made of a plastic material containing at least metallic soap fixed to at least one contact surface of the motor.