JPH0549271A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To obtain an ultrasonic motor having simple structure at low cost wherein the rotor can be rotated through only one type of ultrasonic oscillation source and thereby control of rotational operation is facilitated. CONSTITUTION:The ultrasonic motor comprises a freely oscillating stator 1 having expanding/contracting inner diameter and a rotor 3 inserted rotatably into the central part of the stator 1, wherein the rotor 3 is provided, on the outer peripheral face thereof, with means for converting the oscillation exerted from the inner peripheral face of the stator 1 into driving force for rotating the rotor 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic motor formed to rotate a rotor by utilizing ultrasonic vibration.

[0002]

2. Description of the Related Art In a conventional ultrasonic motor, a rotor is brought into contact with the upper surface of a cylindrical stator, and a piezoelectric element that torsionally vibrates in the circumferential direction of the stator and a longitudinal vibration in the axial direction. By providing a piezoelectric element and combining torsional vibration and longitudinal vibration, the upper surface of the stator is moved so as to draw a Lissajous figure, and the rotor in contact with the upper surface is rotated. There is.

[0003]

However, in the above-mentioned conventional ultrasonic motor, it is necessary to excite both piezoelectric elements so that the frequency of torsional vibration and the frequency of longitudinal vibration coincide with each other, and drive control thereof is required. Requires a high precision, requires an expensive control device, and requires two piezoelectric elements, so that the structure is complicated and the cost is high.

The present invention has been made in view of these points, and the rotor can be rotated by only one kind of ultrasonic vibration source, the rotation operation is easily controlled, the structure is simple, and the cost is low. Another object is to provide an inexpensive ultrasonic motor.

[0005]

In order to achieve the above object, an ultrasonic motor according to the present invention as set forth in claim 1 is provided with a vibrating stator whose inner diameter expands and contracts and a rotatable central part of the stator. And a rotor that is inserted through
The rotor has a driving force converting means for converting a vibration received from an inner peripheral surface of the stator into a driving force for rotating the rotor on an outer peripheral surface thereof.

An ultrasonic motor according to a second aspect of the present invention includes a vibrating stator whose outer diameter expands and contracts, and a rotor which is rotatably loosely fitted to the outside of the stator. The rotor is characterized in that the inner peripheral surface thereof has a driving force converting means for converting the vibration received from the outer peripheral surface of the stator into a driving force for rotating the rotor.

[0007]

According to the ultrasonic motor of the first aspect, when the stator is reciprocally vibrated, the driving force converting means arranged on the outer peripheral surface of the rotor causes the rotor to move due to the vibration of the inner peripheral surface of the stator. The driving force to rotate is taken out, and the rotor rotates in the direction of the driving force.

According to the ultrasonic motor of the second aspect,
When the stator is breathed and vibrated, the driving force converting means arranged on the inner peripheral surface of the rotor extracts the driving force for rotating the rotor due to the vibration that expands and contracts the outer peripheral surface of the stator, and the rotor rotates in the direction of the driving force. To do.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS.

1 and 2 show an embodiment of the present invention.

In the figure, reference numeral 1 is a stator, which is formed in a cylindrical shape. Piezoelectric elements 2 are mounted on the upper and lower end surfaces of the stator 1, respectively. The stator 1 is externally driven by the piezoelectric element 2 at a frequency that causes respiratory vibration that expands and contracts in the radial direction. A shaft-shaped rotor 3 is coaxially inserted through the stator 1, and bearings 4, 4
It is rotatably supported by. The inner peripheral surface 1 of the stator 1 is attached to the outer peripheral surface of the rotor 3 through which the stator 1 is inserted.
Four blades 5, 5 as driving force converting means for converting the vibration received from a into the driving force for rotating the rotor 3.
... are fixed outward at equally divided positions in the circumferential direction. The outer end of each blade 5 is fixed so as to be in contact with the inner peripheral surface 1a of the stator 1 while being inclined by an angle θ with respect to the normal direction of the inner peripheral surface 1a. The external force received by the vibration is divided into a component force component F directed in the tangential direction of the inner peripheral surface 1a to be converted into a driving force for rotating the rotor 3 in the arrow direction of FIG.

Next, the operation of this embodiment will be described.

When the rotor 3 is rotated, when a drive current having a predetermined frequency is applied to the piezoelectric elements 2 and 2, the stator 1 expands and contracts in the radial direction to start respiratory vibration. Each blade 5 receives the radial vibration of the inner peripheral surface 1a of the stator 1 due to this respiratory vibration, and extracts the driving force for rotating the rotor 3 in the clockwise direction in FIG. This driving force causes the rotor 3 to rotate clockwise in FIG.

The rotation speed of the rotor 3 varies the amplitude of respiratory vibration of the inner peripheral surface 1a of the stator 1 and the blade 5
Angle θ of the inner peripheral surface 1a of the stator 1 with respect to the normal direction
It is good to adjust by changing.

When the rotor 3 is stopped, it is preferable to stop the respiratory vibration of the inner peripheral surface 1a of the stator 1.

3 and 4 show another embodiment of the present invention.

The stator 1 of this embodiment is formed in a shaft shape. Piezoelectric elements 2 are mounted on the upper and lower end surfaces of the stator 1, respectively. When these piezoelectric elements 2 and 2 are driven at a frequency that expands in the vertical direction (axial direction of the stator), the stator 1 generates respiratory vibration that expands and contracts in the radial direction. An annular rotor 3 is coaxially and loosely fitted in the stator 1, and is rotatably supported by bearings 4 and 4. On the inner peripheral surface of the rotor 3, four blades 5, 5, ... As driving force converting means for converting the vibration received from the outer peripheral surface 1b of the stator 1 into a driving force for rotating the rotor 3, are equally divided in the circumferential direction. Fixed inwardly in position. The inner end of each blade 5 is the outer peripheral surface 1 of the stator 1.
The components are fixed by inclining by an angle θ with respect to the normal direction of b, and an external force received by the radial vibration of the outer peripheral surface 1b is divided into a component force component F directed in the tangential direction of the outer peripheral surface 1b. The rotor 3 is taken out and converted into a driving force for rotating the rotor 3 in the direction of the arrow in FIG.

Next, the operation of this embodiment will be described.

When the rotor 3 is rotated, when a driving current having a predetermined frequency is applied to the piezoelectric elements 2 and 2, the stator 1 expands and contracts in the radial direction to start respiratory vibration. Each blade 5 receives the radial vibration of the outer peripheral surface 1b of the stator 1 due to the breathing vibration, and extracts the driving force for rotating the rotor 3 in the arrow direction of FIG. This driving force causes the rotor 3 to rotate clockwise in FIG.

As shown in each of the above-described embodiments, the rotor 3 can be rotated by using only one type of piezoelectric element 2 that imparts longitudinal vibration to the stator 1 as a drive source, and two types of conventional piezoelectric elements are used. The control is extremely simple and the structure is simple as compared with the one driven at a predetermined frequency.

Further, in each of the above-mentioned embodiments, the blade 5 is used as the driving force converting means, but the blade 5 is not limited to the blade and may have any constitution as long as it can convert vibration into driving force. Good.

The present invention is not limited to the above embodiment, but can be modified as necessary.

[0023]

As described above, since the ultrasonic motor of the present invention is constructed and operates, the rotor can be rotated only by one kind of ultrasonic vibration source, the control of the rotating operation becomes easy, and the structure is improved. Is also simple, and the cost is low.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of an ultrasonic motor of the present invention.

FIG. 2 is a vertical side view of the center of FIG.

FIG. 3 is a cross-sectional view showing another embodiment of the ultrasonic motor of the present invention.

FIG. 4 is a vertical side view of the center of FIG.

[Explanation of symbols]

 1 stator 1a inner peripheral surface 1b outer peripheral surface 2 piezoelectric element 3 rotor 4 bearing 5 blade

Claims (2)

[Claims] 1. A vibrating stator whose inner diameter expands and contracts,
A rotor that is rotatably inserted through the center of the stator, and the rotor has a driving force that converts the vibration received on the outer peripheral surface from the inner peripheral surface of the stator into a driving force that rotates the rotor. An ultrasonic motor having a converting means. 2. A vibrating stator whose outer diameter expands and contracts,
A rotor that is rotatably loosely fitted to the outside of the stator, and the rotor has a driving force that converts the vibration received on the inner peripheral surface from the outer peripheral surface of the stator into a driving force that rotates the rotor. An ultrasonic motor having a converting means.