JPH0787707B2 - Ultrasonic motor - Google Patents

Description

TECHNICAL FIELD The present invention relates to an improvement of an ultrasonic motor.

(Prior Art and its Problem) An ultrasonic motor is disclosed in, for example, Japanese Patent Application Laid-Open No. 58-14
As disclosed in Japanese Patent No. 8682, by applying a high frequency voltage to a piezoelectric body fixed to an elastic body, by generating ultrasonic elliptical vibration on a predetermined surface of the stator,
The rotor, which makes pressure contact with the stator, is given a rotational motion by frictional vibration. Compared with the conventional electromagnetic motor, there are no windings, the structure is simple, and ultrasonic vibration energy with high energy density is used. Therefore, it is a motor that has recently been attracting attention from various fields due to its features such as small size, low speed, high torque, high responsiveness, and excellent controllability.

However, in order to achieve high efficiency and high torque of this motor, it is necessary to increase the pressing force of the rotor and the stator, and in particular in this connection, improvement of the mutual pressure contact portion between the rotor and the stator is required. There is.

(Means for Solving the Problems) Therefore, in order to solve the above problems, according to the present invention, one or both contact surfaces of a stator and a rotor are processed into a tapered shape or a spherical shape, so that pressure contact is performed. ,
The contact surfaces of the stator and rotor are made uniform to provide a higher performance ultrasonic motor.

(Operation) According to the present invention, (1) an ultrasonic motor having high efficiency (2) an ultrasonic motor producing a high torque (3) an ultrasonic motor having a long life can be realized.

(Examples) Examples of the present invention will be described below.

FIG. 1 is a side view showing the external appearance, FIG. 2 is a plan view, 1 is a case of the present ultrasonic motor, and 2 is an integrated cover. Further, FIG. 3 shows an AA cross section in FIG. Referring now to FIG. 3, the elastic body 3 forming the stator (vibrating body) 5 includes
A piezoelectric body 4 such as a piezoelectric ceramic is fixed.

Further, the rotor 8 which is in pressure contact with the stator 5 has a slider 7 made of a high-performance engineering plastic or a high-performance rubber having a high friction coefficient and a small wear amount on the ring 6.
Is fixed. Naturally ring 6 depending on the application
May be made of the same material as the slider 7 to form the rotor 8.

The rotor 8 is pressed against the stator 5 by the pressing force of the flat spring 10, and rotates integrally with the shaft 11 via the flat spring 10.

The pressing force is adjusted by the thickness of the shim 12 and then snap ring
Holds constant by 13.

When two or more types of high-frequency voltages are applied to the piezoelectric body 4 that has been subjected to the alternating polarization treatment, elliptical vibration due to an elastic traveling wave occurs in a predetermined surface area of the stator 5.

The slider 7 that is in pressure contact therewith is frictionally driven in a fixed direction by its elliptical vibration, so that the rotor 8 and the shaft 11 that are integrated rotate.

By attaching pulleys and gears to the shaft 11,
The output of this motor can be taken out. (Not shown) This ultrasonic motor has a so-called drooping characteristic as in the case of a general electromagnetic motor, but in the case of obtaining a motor with high efficiency and large output torque, It is necessary to increase the pressure applied to the rotor 8 and the stator 5 by the flat spring 10. In the past, since the applied pressure was a few kilograms (stator size of φ60), which was comparatively small, regarding the mutual surface contact and the contact surface pressure condition of the rotor 8 and the stator 5 in the pressurized state, elastic deformation was taken into consideration especially at the time of pressurization. Even if it was not put in, the motor characteristics showed satisfactory values.

However, as shown above, when attempting to improve the efficiency and torque of this ultrasonic motor, the applied pressure is
It has been found that the elastic characteristics due to the pressurization of the rotor 8 or the stator 5 have a great influence on the motor characteristics because the load is as high as 10 kg or more.

Next, a case where elastic deformation due to pressurization occurs in the rotor will be described.

As shown in FIG. 4, the rotor 8 is in the state a before the pressurization and is in the state b due to the elastic deflection of the rotor member during the constant pressurization after the pressure adjustment.

As can be seen from this, only the inner peripheral portion of the slider 7 is in contact with the elastic body 3 of the stator 5 during pressurization, and the pressure distribution is as shown in FIG. Since p is the surface pressure, which is higher toward the inner circumference side and is evenly applied inside and outside, the slider is worn more or less, and the output torque is low. Therefore, as shown in the present invention, when the rotor is designed and processed, it is necessary to obtain the elastic deflection of the rotor in advance and press the rotor according to the amount of the deflection. Specifically, as shown in FIG. 6, if the slider 7 of the rotor 8 is to be lapped, it is processed with a convex platen having a local ratio ρ corresponding to the deflection due to the pressing force. Processing is performed with a constant gradient θ. Since the width B of the contact portion between the rotor 8 and the stator is smaller than the diameter A, the curved surface plate makes a sufficiently uniform contact during the lapping.

Although the case where the pressure is applied to the inner peripheral side of the rotor 8 has been described above, when the pressure is applied to the outer peripheral side, a concave surface plate is used in the lapping process and a constant gradient is used in the mechanical processing. .

Further, when the stator 5 is elastically deformed, the contact surface with the rotor is processed based on the same idea as in the case of the rotor.

Further, when both the rotor 8 and the stator 5 are elastically deformed by the applied pressure, both or either of them is optimally processed according to the conditions.

(Effects of the Invention) As described above, the present invention is an ultrasonic motor in which the contact surface pressures of the rotor and the stator are uniform and constant when the rotor and the stator are in pressure contact, and the following effects are expected. it can.

(1) The pressure contact between the rotor and the stator is uniform and constant, resulting in high efficiency and high output torque.

(2) Since the contact surface pressure is uniform, the amount of wear is stable and the life is extended.

[Brief description of drawings]

FIG. 1 is a side view of one embodiment of the present invention, FIG. 2 is a plan view of the present invention, FIG. 3 is a sectional view taken along the line AA of FIG. 2, FIG. 4 is a rotor detailed view, and FIG. FIG. 6 is an enlarged view of the distribution of the pressing force and an enlarged view of the pressure contact portion, and FIG. 6 is a rotor machining drawing. 9 …… Rubber body, 14, 15 …… Bearing

Claims (3)

[Claims] 1. An ultrasonic motor comprising a stator and a rotor, wherein the contact surface of the rotor with respect to the stator is tapered or spherical with elastic deformation occurring when the stator and rotor are in pressure contact with each other. An ultrasonic motor in which the contact surface pressure between the stator and rotor is made uniform by processing it into a shape. 2. The contact surface between the stator and the rotor is formed by processing the contact surface of the stator with respect to the rotor into a tapered shape or a spherical shape in consideration of elastic deformation that occurs when the stator and the rotor are in pressure contact with each other. The ultrasonic motor according to claim 1, wherein the pressure is uniform. 3. A stator is manufactured by processing the contact surfaces of both the stator and the rotor into a tapered shape or a spherical shape in consideration of elastic deformation that occurs when the stator and the rotor come into pressure contact with each other. The ultrasonic motor according to claim 1, wherein the contact surface pressure between the rotor and the rotor is uniform.