JPH0834701B2 - Ultrasonic motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention provides a traveling wave excited by mechanical resonance on the surface of a disk-shaped piezoelectric vibrator formed of an electrostrictive element, a piezoelectric element, a magnetostrictive element, or the like. The present invention relates to an ultrasonic motor used, and more particularly, to an ultrasonic motor capable of maintaining rotation transmission efficiency and uniform rotation drive by always ensuring contact surfaces between a stator and a rotor that are in pressure contact with each other. .

(B) Conventional Technology Conventionally, as shown in FIGS. 4 and 5, an ultrasonic motor has a disk-shaped piezoelectric vibrator 1 attached to the back surface of an elastic body 3 formed around a disk 2. A stator 4 is provided, a shaft hole 6 is opened in the center of the disk 5, and a circular rotor 7 formed in the periphery is pressed against the surface of the elastic body 3 of the stator 4, so that the disk 2 of the stator 4 A thick portion 2'having a shaft insertion hole 8 in the center is fixed to a central thick portion 9'of a bottom plate of a housing 9, and a shaft 11 rotatably attached to the thick portion 9'via a bearing 10 is attached. It is loosely fitted in the shaft insertion hole 8 of the disk 2 of the stator 4 and press-fitted and fixed in the shaft hole 6 of the disk 5 of the rotor 7, and the disk 5 is supported by the nut 12 at the end of the shaft 11. Since the disc spring 14 or the like is pressed by the plate 13, the disc spring 14 or the like is constantly urged toward the stator 4. According pressurization rotor 7 and the elastic member 3 of the stator 4
It will be done inside the contact surface with. In pressurizing with such a structure, since the supporting portion of the stator 4 and the point of action of pressurizing the rotor 7 are on the same side with respect to the contact surface, as shown in FIG. 2 is bent by the pressing force of the spring, bent by the vibration of the stator, or bent due to metal fatigue such as change with time, so that the rotor 7 is bent toward the disc spring 14 and the stator 4 is bent in the opposite direction. As a result, the contact surfaces of the stator 4 and the rotor 7, which are in pressure contact with each other, open to the outside, resulting in poor contact, resulting in poor rotation transmission efficiency and uneven rotation drive, resulting in non-uniformity.

(C) Problems to be Solved by the Invention A problem to be solved by the present invention is that the pressure contact surface between the stator and the rotor in the ultrasonic motor is always ensured with a simple structure. An object of the present invention is to provide an ultrasonic motor capable of eliminating the above drawbacks at once and maintaining the rotation transmission efficiency and making the rotation drive uniform.

(D) Means for Solving the Problems The present invention has been made by paying attention to such conventional problems. The housing, the stator to which the vibrator is attached, and the stator are pressed and contacted. In an ultrasonic motor including a rotor and a rotating shaft that is rotatably supported by the housing and rotates integrally with the rotor, the stator is fixedly supported by the housing at an inner peripheral portion,
The present invention provides an ultrasonic motor characterized in that a point of pressurizing action on the rotor is provided outside a position where the stator is supported, with a contact surface between the stator and the rotor being sandwiched therebetween.

(E) Operation Next, the operation of the present invention will be described.

According to the present invention, the stator is fixedly supported by the inner peripheral portion of the housing, and the point of pressurizing action on the rotor is provided outside the supporting position of the stator with the contact surface between the stator and the rotor being sandwiched therebetween. The rotor and the stator are bent in the same direction as the rotor due to the bending of the spring due to the pressing force of the spring, the bending of the stator due to the vibration of the stator, and the bending of the metal fatigue such as the change over time. Therefore, the contact surfaces of the stator and the rotor, which are in pressure contact with each other, do not open and the surface contact state is maintained, whereby the rotation transmission efficiency is maintained and the rotation is uniformly driven.

(F) Example Hereinafter, the present invention will be described with reference to the drawings.

1 and 2 show an embodiment of the present invention.

A stator 4 formed by attaching a disk-shaped piezoelectric vibrator 1 to the back surface of an elastic body 3 formed on the periphery of the disk 2 is provided, and a shaft hole 6 is opened at the center of the disk 5 and at the periphery thereof. The formed circular rotor 7 is made to correspond to the surface of the elastic body 3 of the stator 4, and a flange portion 15 is integrally formed on the outside of the rotor 7 so as to project. A thick portion 2'having a shaft insertion hole 8 formed at the center of the disc 2 of the stator 4 is fixed to a central thick portion 9'of the bottom plate of the housing 9, and the thick portion 9'via a bearing 10 to the thick portion 9 '. The shaft 11 rotatably attached is loosely fitted in the shaft insertion hole 8 of the disk 2 of the stator 4 and the shaft hole 6 of the disk 5 of the rotor 7. Elastic body 3 of the flange portion 15 of the rotor 7
The shaft 11 is press-fitted and fixed to a shaft hole 18 having a circular body 16 in contact with the surface opposite to the side, and the plate 17 is supported by a nut 12 at the end of the shaft 11. It is constantly urged toward the stator 4 by a disc spring 14 or the like that is pressed by the plate 13.

With the above structure, the rotor 7 and the stator 4 are
When the outer flange portion 15 is bent by pressing, the rotor 7 is bent toward the stator 4 and the stator 4 is bent in the same direction as shown in FIG.

FIG. 3 shows another embodiment of the present invention in which the stator 4 and the rotor 7 are formed in an annular shape.
A flange portion (22) that is formed so as to project on the inner circumference of the annular elastic body (21) is engaged with and supported by a step portion (24) formed at the tip of a cylindrical housing (23).

In the figure, parts designated by the same reference numerals indicate the same constituent parts.

(G) Effect of the Invention As is apparent from the above description, the present invention maintains uniform surface contact even when the rotor and the stator with which it makes surface contact are deflected by the pressure applied to the rotor, so that rotation transmission is maintained. The efficiency is maintained without lowering, the rotation drive is not unevenly accompanied thereby, and uniform and good rotation can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the structure of an embodiment of the present invention, FIG. 2 is a cross-sectional view showing the same bending state, and FIG. 3 is a cross-sectional view showing the structure of another embodiment of the present invention. FIG. 4 is a cross-sectional view showing the structure of a conventional example, and FIG. 5 is a cross-sectional view showing a state in which the same bending is generated.

Claims (1)

[Claims] 1. A housing, a stator having a vibrator attached thereto, a rotor in pressure contact with the stator, and a rotating shaft rotatably supported by the housing and rotating integrally with the rotor. In the ultrasonic motor, the stator is fixedly supported by the inner peripheral portion of the housing, and a point of pressure acting on the rotor is sandwiched by a contact surface between the stator and the rotor with respect to a support position of the stator. An ultrasonic motor characterized by being provided outside.