JPH0578197U - Ultrasonic motor - Google Patents

Abstract

(57) [Abstract] [Purpose] To achieve miniaturization, easy assembly, and improvement of rotational torque. [Structure] An intermediate rotor 5 is in contact with a peripheral surface of a disk-shaped stator 7 having a piezoelectric element. A spring 13 is urged so that the inner peripheral surface portion 10a of the output rotor 10 comes into contact with the outer peripheral surface portion 5a at the tip of the intermediate rotor 5. The outer peripheral surface portion 5a and the inner peripheral surface portion 10a are tapered.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an ultrasonic motor in which a piezoelectric element is given a radial stretching vibration mode and an in-plane bending vibration mode to rotate a rotor by an elliptic motion generated on the peripheral surface of the piezoelectric element.

[0002]

[Prior Art]

 FIG. 3 is a plan view showing a schematic configuration of a conventional ultrasonic motor. In the figure, reference numeral 20 is a disk-shaped stator, and a pair of half-moon shaped piezoelectric ceramics 21 are attached to the surface. Reference numeral 22 denotes a transmission member having a rectangular cross section, which is fixed to points A on the circumferential surface of the stator 20 facing each other, and is formed of plastic to obtain a predetermined friction transmission force. A pressing member 23 rotatably supports a pressing roller 24 on a shaft 25 spanned by a shaft 25, and is biased by a compression spring 26 so as to press the pressing roller 24 toward the transmission member 22 side. The peripheral surface of the rotor 27 attached to the rotating shaft 28 is rotatably abutted on the other transmitting member 22, and the rotating shaft 28 rotating integrally with the rotor 27 is pivotally supported by a case (not shown). Project from the case to form the output shaft.

In such a configuration, the piezoelectric ceramic 21 has a radial stretching vibration mode as shown in FIG. 4A and an in-plane bending vibration mode in the vertical direction as shown in FIG. 4B. When the phases of these vibration frequencies are shifted, as shown in FIG. 4 (c), at two points (point A in the figure) on the peripheral surface on the horizontal line passing through the center line of the stator 20, the directions are opposite to each other. A rotating elliptical motion occurs. The elliptic movement of the stator 20 at point A is transmitted to the rotor 27 via the transmission member 22 and can be taken out from the output shaft 28 as a rotational movement.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In the above-described conventional ultrasonic motor, rotors are arranged on both sides of the peripheral surface of the stator, and the rotor side surfaces are arranged so that the rotor contacts the peripheral surface of the stator. Since the structure is such that the spring biases the components, the rotor, springs, and other parts must be arranged in the circumferential direction of the stator, which poses the problem that the planar size cannot be reduced. Further, in order to prevent the rotor from moving due to the elliptical movement of the stator peripheral surface, it is necessary to match the center of the stator with the center of the pair of rotors, and it is also necessary to adjust the biasing direction of the spring. The processing and adjustment accuracy of each component is required, the adjustment becomes complicated, and the rotational torque of the rotor cannot be obtained sufficiently. Therefore, the present invention has been made in view of the above-mentioned conventional problems or drawbacks, and an object thereof is to achieve miniaturization, easy assembly, and improvement of rotation torque. To provide a sonic motor.

[0005]

[Means for Solving the Problems]

 In order to achieve this object, the ultrasonic motor according to the present invention is provided with a disk-shaped stator and a radial stretching vibration mode and an in-plane bending vibration mode provided on the surface of the stator. A piezoelectric element that causes an elliptical motion on the peripheral surface of the stator, an intermediate rotor that comes into contact with the peripheral surface of the stator and rotates, and has a tapered surface with a trapezoidal cross-section at the outer periphery of the tip portion, and the tapered surface of this intermediate rotor. It is composed of an output rotor that has a tapered surface that abuts in a reverse tapered shape on the inner peripheral surface and that rotates, and a biasing means that biases this output rotor toward the intermediate rotor along the direction of the rotation axis. is there. In the ultrasonic motor according to the present invention, the tapered surface of the output rotor is in contact with the peripheral surface of the stator on the side opposite to the intermediate rotor.

[0006]

[Action]

 In the present invention, a tapered surface is formed on the outer periphery of the tip of the intermediate rotor that rotates by contacting the peripheral surface of the elliptical stator, and the tapered surface that abuts in reverse taper shape on the inner surface is formed. Since the output rotor on the surface is biased toward the intermediate rotor along the output shaft, the output rotor is arranged in a stacked state with respect to the stator, and the tapered surface of the output rotor causes the intermediate rotor to always be in the center direction of the stator. Be urged by.

[0007]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. 1 is a front sectional view of an ultrasonic motor according to the present invention, and FIG. 2 is a sectional view taken along line II-II of FIG. In these drawings, the reference numeral 2 is a base, and a shaft 3 having a threaded portion 3a formed at the tip is erected upright at the center, and a bearing 2 is provided in a hole 2a bored at the end. Are fitted and fixed. A stepped cylindrical intermediate rotor 5 is rotatably supported on the bearing 4, and a tapered surface 5a having a trapezoidal cross section is formed on the outer peripheral portion of the tip end of the intermediate rotor.

A disk-shaped stator 7 is placed on the base 2 via a felt 6 which is a vibration absorbing material. A chamfered portion 7a is provided at the peripheral edge of the upper end surface of the stator 7, and a central portion is provided. Holes 7b are provided respectively, a pair of substantially semicircular piezoelectric elements 8a and 8b are fixed to the front surface, and circular piezoelectric elements (not shown) are fixed to the rear surface, and terminals 9a, 9b and 9c are respectively led out. Has been done.

Reference numeral 10 denotes a cap-shaped output rotor having the shaft 3 as a rotation support shaft, and a taper surface 10a having the same taper angle as the taper surface 5a of the intermediate rotor 5 is formed on the inner peripheral portion of the outer peripheral edge. The output rotor 10 is pressed downward in the figure by a spring 13 interposed between a washer 12 and a nut 14 screwed onto the threaded portion 3a of the shaft 3, whereby the tapered surface 10a of the output rotor 10 is pressed. Is pressed against the tapered surface 5a of the rotor 5 in an inversely tapered shape, and the tapered surface 10a on the opposite side of the rotor 5 presses the chamfered portion 7a of the stator 7.

The pressing force can be adjusted by adjusting the advancing / retreating amount of the nut 14 since the abutting portions are both constituted by the tapered surfaces 5a and 10a, and at the same time, the wedge operation of the taper surfaces 5a and 10a is performed. As a result, the contact force of the intermediate rotor 5 on the stator 7 can also be adjusted. Therefore, by adjusting the amount of advance / retreat of the nut 14 after assembly, the contact force between the output rotor 10 and the intermediate rotor 5 and the contact force between the intermediate rotor 5 and the stator 7 can be adjusted, and at the same time in manufacturing each component. Since it is also possible to adjust the error in the above and the error in assembling, manufacturing and assembling are facilitated. Therefore, the rotational drive from the stator 7 to the output rotor 10 is smoothly performed, and the output torque can be improved. At the same time, the intermediate rotor 5 is pressed toward the stator 7 side by the tapered surface 10a at the inner peripheral portion of the outer peripheral edge of which the cross section of the output rotor 10 having the shaft 3 as the rotation supporting shaft is circular. The center is not biased by being biased toward the center of.

When two AC voltages having the same frequency but different phases of 90 ° are applied to the pair of piezoelectric elements 8a and 8b of the ultrasonic motor configured as described above, an elliptic motion occurs on the peripheral surface of the stator 7. The intermediate rotor 5 rotates counterclockwise in FIG. 2, and the output rotor 10 also rotates counterclockwise accordingly. Since the output rotor 10 is in direct contact with the peripheral surface of the stator 7 on the opposite side of the intermediate rotor 5, counterclockwise rotational output is obtained from this contact portion as well, and the rotational torque of the output rotor is improved. The obtained rotary torque is output to the outside by a gear mechanism (not shown) or the like.

[0012]

[Effect of the device]

 As described above, according to the present invention, a tapered surface is provided on the outer peripheral portion of the tip end portion of the intermediate rotor that rotates by contacting the peripheral surface of the stator, and the tapered surface that abuts the tapered surface of the intermediate rotor in a reverse taper shape. Since the output rotor which has the inner peripheral surface and rotates is provided, the components such as the output rotor can be arranged in a laminated state with the stator, which enables downsizing. .. Further, since the urging means for urging the output rotor toward the intermediate rotor side is provided, the contact force between the output rotor and the intermediate rotor and the contact force between the intermediate rotor and the stator can be adjusted, and at the time of manufacturing each component. Error and assembling error can be adjusted, and since the intermediate rotor is pressed toward the center of the stator by the tapered surface of the output rotor, the center of the intermediate rotor does not deviate from the center of the stator 7. Therefore, the rotational drive from the stator to the output rotor is smoothly performed, and the output torque can be improved. Further, since the tapered surface of the output rotor is in contact with the peripheral surface of the stator even on the opposite side of the intermediate rotor, the rotational torque of the output rotor is further improved.

[Brief description of drawings]

FIG. 1 is a front sectional view of an ultrasonic motor according to the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a plan view of a conventional ultrasonic motor.

FIG. 4 is a diagram illustrating an operation principle of a general ultrasonic motor.

[Explanation of symbols]

 5 Intermediate rotor 7 Stator 10 Output rotor

Claims (2)

[Scope of utility model registration request] 1. A disk-shaped stator, and a piezoelectric element which is disposed on the surface of the stator and is given a radial stretching vibration mode and an in-plane bending vibration mode to generate an elliptical motion on the peripheral surface of the stator. , An intermediate rotor having a tapered surface on the outer periphery of the tip end, which rotates by abutting on the peripheral surface of the stator, and an inner peripheral surface having a tapered surface abutting against the tapered surface of the intermediate rotor in an inversely tapered shape and rotating. An ultrasonic motor comprising: an output rotor; and an urging means for urging the output rotor toward the intermediate rotor along the rotation axis direction. 2. The ultrasonic motor according to claim 1,
An ultrasonic motor, wherein a tapered surface of the output rotor is in contact with a peripheral surface of the stator on a side opposite to the intermediate rotor.