JPH0223072A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To improve adhesiveness and mass productivity by replacing metal with ceramics and glass as a component material of a stator. CONSTITUTION:In an ultrasonic motor, a piezoelectric element 2 is supported by a vibration base 1 which forms a stator. A rotor 3 is brought into contact with a stator 1 through a lining material 4. The material of the base 1 is composed of ceramics and glass. Thus, it can be manufactured without reducing mechanical working accuracy, and the same motor characteristics as those of metal stator can be resultantly obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a small motor, and particularly to an ultrasonic motor using E-sonic vibration.

BACKGROUND OF THE INVENTION Ultrasonic motors use ultrasonic vibrations as a driving force source. In general, it is desirable to select a material with low internal loss of vibration for the vibrating body of the motor in terms of efficiency of the ultrasonic motor.

Furthermore, in order to vibrate the vibrating body efficiently, it is important that its geometrical shape generates a stable vibration mode.

Metal has been selected as the vibrating body of an ultrasonic motor due to two reasons: internal loss and ensuring a highly accurate shape. Iron or iron alloys are used as materials with particularly low internal loss.

Problems to be Solved by the Invention Since the ultrasonic motor has a simple structure, it is thought that it can be manufactured easily and at a low cost. However, because the accuracy requirements for the vibrating body are strict, the price is currently higher than conventional motors that use electromagnetic force.

The reason for the high price is that the processing method is cutting, which guarantees accuracy.

Therefore, it is desired to establish a processing method that does not rely on the cutting lf method and still guarantees accuracy.

A piezoelectric material is essential for generating vibrations in an ultrasonic motor. Since the expansion coefficient of piezoelectric bodies is generally smaller than that of metals, the material of the stator, which is the vibrating body, is limited in order to match the expansion coefficients. There is a demand for vibrating body materials that can be replaced with metal due to the following three points: expansion coefficient, density (to reduce the weight of the motor as much as possible), and price.

The vibrating body is not limited to metal.

If we were to take an example from everyday life, the best example would be the wind chime. Wind chimes are made of materials with low internal loss.

This results in the sound lasting longer. Furthermore, a beautiful tone is required, which leads to the generation of a simple vibration mode.If we were to list the materials for wind chimes, we would immediately think of southern iron.

Next, you should be able to automatically think of ceramic pottery or glass. If ceramics such as glass are appropriately designed in this way, they can be applied to stators that serve as drive sources for ultrasonic motors.

On the other hand, manufacturing the vibrating body of an ultrasonic motor without degrading the characteristics of the motor is the key to expanding the range of applications of the ultrasonic motor. At present, the cutting methods for metal materials have achieved almost satisfactory values in terms of efficiency, lifespan, and properties, but how can we reduce costs and develop new processing methods that are comparable to cutting methods? The biggest challenge at the moment is how to implement this method.

At present, casting and forging methods cannot meet the requirements for motor characteristics due to lack of precision, and die casting methods still have problems because the materials that can be selected for the stator do not match the motor characteristics. Similarly, the sintering method cannot be used because the loss due to ultrasonic vibration is large.

No suitable processing method was found within the scope of the above study.

Means for Solving the Problems The present invention has been made in view of the above problems, and includes a vibrating base that supports a piezoelectric body made of ceramic or glass.

Another major advantage of ceramics and glass is that they have better rust prevention effects than metals.

Function: By using ceramic or glass as the stator material of an ultrasonic motor, the present invention can be manufactured without reducing the mechanical processing accuracy, and the motor characteristics are similar to those of a metal stator. Further, it has the following effects regarding the expansion coefficient, adhesion 111 with the piezoelectric body, etc.

a: The processing method of l11 can be done by an inexpensive means such as a press.

b = swelling 11. The range of i-coefficient selection is expanded.

c:R Material selection with low mechanical internal loss becomes possible.

d: Good adhesion to piezoelectric material.

Embodiment FIG. 1 shows a configuration diagram of an ultrasonic motor. In FIG. 1, reference numeral 1 denotes a vibrating base body constituting a stator, which supports a piezoelectric body 2. 3 is a rotor, which is in contact with the stator via a lining material 4. In FIG. 1, the vibrating base 1 is made of ceramic or glass.

The most excellent configuration in terms of expansion coefficient and adhesion between the vibrating base 1 and the piezoelectric body 2 made of ceramic is to use the same material for the vibrating base 1 as the driving piezoelectric body. However, this configuration still poses a problem in the method of machining the stator, since machining the piezoelectric body increases costs.

In the configuration shown in Figure 1, we constructed a vibrating base for an ultrasonic motor using a processing method using ceramic and glass press processing, and examined the motor characteristics. It was confirmed that the characteristics are comparable to those of motors. In particular, the motor characteristics at low temperatures showed rather excellent results.

FIG. 2 shows the expansion coefficient of the piezoelectric ceramic both when the piezoelectric body is polarized (solid line) and when it is not polarized (broken line). Furthermore, the expansion coefficient shows values in two directions: a direction parallel to the polarization direction of the piezoelectric material (A), and a direction perpendicular to the polarization direction (B) (7). Generally, in the case of the ultrasonic motor shown in Figure 1, the latter expansion coefficient in the right angle direction is important, and this value is 5X10
'/°C to 7×10'G/°C, and there are only a limited number of metals that can match this value. However, materials with expansion coefficients of this value are common for ceramics and glasses, and ceramics and glasses are easy to use due to the flexibility in selecting materials.

Effects of the Invention By changing the constituent material of the stator of an ultrasonic motor from metal to ceramic or glass, the present invention does not impair the degree of freedom in workability that metal has, and also achieves better consistency in properties and expansion coefficient than when using metal. It provides excellent adhesiveness, adhesion, and mass productivity.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an ultrasonic motor, and FIG. 2 is a diagram showing the expansion coefficient of a piezoelectric material used in the ultrasonic motor in the horizontal and vertical directions, as well as the values in the case where there is no polarization. 1... Vibration base, 2... Piezoelectric body. Figure 2 Figure 1-11-9 ○ Mixed cliff (0C)

Claims (6)

[Claims] (1) In an ultrasonic motor that uses ultrasonic vibrations as a drive source, the stator that generates ultrasonic vibrations is composed of a piezoelectric body that serves as a drive source for generating vibrations, and a vibrating base that supports the piezoelectric body. An ultrasonic motor whose basic vibration is made of the same material as the piezoelectric body. (2) In an ultrasonic motor that uses ultrasonic vibrations as a drive source, the stator that generates ultrasonic vibrations is composed of a piezoelectric body that serves as a drive source for generating vibrations, and a vibrating base that supports the piezoelectric body. This ultrasonic motor has a vibrating base made of ceramic. (3) In an ultrasonic motor that uses ultrasonic vibrations as a drive source, the stator that generates ultrasonic vibrations is composed of a piezoelectric body that serves as a drive source for generating vibrations, and a vibrating base that supports the piezoelectric body. and an ultrasonic motor using a stator in which the vibrating base is made of glass. (4) In an ultrasonic motor that uses ultrasonic vibration as a driving source, the stator for generating ultrasonic vibration is composed of a piezoelectric body that serves as a driving source for generating vibration, and a vibrating base that supports the piezoelectric body. and an ultrasonic motor in which the vibrating base is made of ceramic, and the expansion coefficient of the ceramic is made to match the expansion coefficient of the piezoelectric body. (5) In an ultrasonic motor that uses ultrasonic vibrations as a drive source, the stator for generating ultrasonic vibrations is composed of a piezoelectric body that serves as a drive source for generating vibrations, and a vibrating base that supports the piezoelectric body. , an ultrasonic motor in which the vibrating base is made of glass, and the expansion coefficient of the glass is made to match the expansion coefficient of the piezoelectric body. (6) The ultrasonic motor according to claim 4 or 5, wherein the expansion coefficient of the piezoelectric body in a direction perpendicular to the polarization direction and the expansion coefficient of the vibrating base body are made equal to each other.