JPH0117353B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a drive method and motor device that utilize ultrasonic vibrations.

More specifically, the present invention relates to a novel drive method that utilizes the powerful vibrational energy of ultrasonic waves, and a motor device based on this method.

(Background Art) Most of the various motor devices that have been widely used in the past have applied electromagnetic forces as their driving sources, and are used for various purposes. However, the size, weight, rotational force (torque), etc. of these devices are limited by the materials used. This is because the size, weight, rotational force, etc. are determined by the magnetic properties of the materials used, and it is impossible for devices that exceed these properties to be rotated. This is to become. On the other hand, as a device that overcomes the limitations of the various conventional motor devices mentioned above and replaces them, the present inventor has proposed a motor device using ultrasonic vibrations, which is disclosed in Japanese Patent No. 1262645 (Japanese Patent Publication No. 59-30912). Patent Application No. 55-40656)] Rotary drive device using ultrasonic vibration Patent No. 1264258 [Special Publication No. 5937672 (Patent Application No. 31955/1982)] Unidirectional device using ultrasonic vibration Drive device = Patent No. 1264296 [Special Publication No. 59-37673
(Japanese Patent Application No. 55-152753)] has already been proposed. These prior inventions by the present inventor are:
One end of the vibrating body vibrated by the ultrasonic vibrator and one end face of the moving body are placed in positions facing each other, a plate-shaped or rod-shaped vibrating piece is interposed between the two, and the vibrating piece is tilted at an appropriate angle. The present invention relates to a device that converts the reciprocating motion of an ultrasonic transducer into unidirectional motion of a moving object.

In addition, there is a separate patent No. 1345496 [Special Publication No. 58-32518
As disclosed in Japanese Patent Application No. 50-105847, a method has been proposed in which a rotor is rotationally driven using vibrations generated when a high frequency voltage is applied to a piezoelectric element.

These advanced technologies convert the powerful vibrational energy of ultrasonic waves into rotational or linear motion, making them compact and lightweight, and compared to conventional electromagnetic motors, they do not require windings, so they have a simpler structure. However, what they all have in common is that they are all ultrasonic motors that use standing waves, and there are significant restrictions on their structure and performance. For example, they have drawbacks such as poor durability and rotation only in one direction.

(Disclosure of the Invention) The purpose of the present invention is to provide a new drive method that is completely different from the conventional motor devices as described above and has high characteristics and excellent functionality, and a motor device that uses the same. .

In order to achieve this object, the present invention configures an ultrasonic transducer with a plurality of electrostrictive elements and an elastic body, and applies high-frequency voltages with temporally different phases to the electrostrictive elements arranged in parallel. By applying , a traveling wave capable of forming an elliptical vibration is generated on a predetermined surface of the ultrasonic vibrator, and a moving object is placed in pressure contact with the predetermined surface of the ultrasonic vibration. Therefore, the present invention provides a driving method and a motor device using ultrasonic vibration in which a moving body is frictionally driven in a predetermined direction.

With the above-mentioned characteristics, the present invention realizes a drive method and motor device using ultrasonic vibration that can easily perform forward and reverse rotations.A drive method and motor device using ultrasonic vibration that are highly durable.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The operating principle and embodiments of the method and motor device of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a partially enlarged perspective view for explaining the principle of operation. 1 is an elastic body such as metal. Note that this figure does not show a vibration source such as an electrostrictive element, and shows a state in which a traveling wave is generated on the surface 1' of the elastic body, which can form an elliptical vibration that is a combination of transverse vibration and longitudinal vibration. Shown enlarged. One method for generating the traveling wave described above is to use a surface wave, generally called a Rayleigh wave, that propagates along the surface of an elastic body. This Rayleigh wave/surface wave has already been logically clarified. There are two types of elastic waves that propagate through a solid: longitudinal waves and transverse waves, which exist independently, but due to the boundary conditions of the surface, they intertwine and become synthesized. In order to generate this Rayleigh wave, an electrostrictive element or the like that vibrates vertically or horizontally may be provided in the ultrasonic vibrator and excited.

Further, as another method, bending vibration of a rod-like or plate-like elastic body can be used. This is because longitudinal waves and transverse waves are combined on a given surface of an elastic body.
It utilizes the generation of traveling waves that can form elliptical vibrations.

In order to generate this bending vibration wave, high frequency voltages having temporally different phases may be applied to a plurality of electrostrictive elements arranged in an ultrasonic transducer so as to have a phase difference.

Now, if we pay attention to mass point B on the surface of the elastic body shown in Fig. 1, mass point B has a lateral amplitude a (vertical direction).
It is moving in the direction of arrow M on an ellipse Q, which is a composite of the vertical oscillation width b (horizontal direction), and its traveling wave is
It is moving in the direction of arrow U at a speed of phase velocity γf (where γ is the wavelength and f is the frequency).

When the moving body 2 is pressed into contact with the surface of the elastic body 1 under this condition, the moving body 2 comes into contact only at the apexes A and A' of the elliptical vibration of the elastic body 1. Furthermore, since the vertices A and A' are moving in the direction of the arrow N at a vibration velocity v = 2πfb (where f is the frequency), the moving body 2 in pressurized contact is moved by the arrow N due to the frictional force with the elastic body 1. It will be driven in the direction of.

FIG. 2 shows an example of a motor device based on such an operating principle.

FIG. 2A is a partial sectional view of this example, and FIG. 2B is a sectional view taken along the line A--A. In this example,
Inside the casing body 31, supported by a support member 32, an electrostrictive element 37 is mounted on a ring-shaped bending elastic body 30.
A vibrator 33 to which a rotor 34 is fixed is disposed, and a taper 33' is provided on the inner peripheral surface of the vibrator 33. The rotor 34 is supported so as to be movable in the axial direction with respect to the rotating shaft 35. In addition, a pressure regulating mechanism 36 shown in FIG. 3 is provided,
Rotational force is transmitted to the rotating shaft 35. 38 indicates a pivot support.

FIG. 3 is a sectional view showing an example of the pressure regulating mechanism 36, and shows an example of an automatic pressure regulating mechanism. Rotating axis 3
5 and the rotor 34, a cam 2 with a V-shaped bottom is disposed between the cam 2 and the rotor 34.
By providing a pair of steel balls 3 and 24 and a plurality of steel balls 25 interposed between them, the steel balls are located at the bottom of the cam when no load is applied, but as the load is applied and the torque increases, the steel balls are placed at the bottom of the cam. The rotor 34 functions to ride up the groove and generate pressure in the axial direction, thereby transmitting the torque of the rotor 34 to the rotating shaft 35 side.

In Figure 2 B (in the same figure, the casing body 3
1) Ring-shaped bending elastic body 3
The electrostrictive element 37 fixed to the outer periphery of the electrode is divided into eight regions, and each electrostrictive element is polarized in the direction shown by the arrow ↓↓↓ or ↑↑↑ so that it expands and contracts in the circumferential direction. Each divided electrostrictive element A,
On the outer periphery of B, C, D, E, F, G, H are electrodes a,
b, c, d, e, f, g, h, and electrodes a,
Electrodes b, c, and d are connected and led to a terminal 39, and similarly electrodes e, f, g, and h are connected and led to a terminal 40.

In this structure, when a voltage is applied between the terminal 39 or terminal 40 and the elastic body 30, each electrostrictive element expands in the portion indicated by ←→ as shown in FIG. 4, depending on the polarization direction. The elastic body 30 bends inward with respect to the axis. At the same time, the portion indicated by →← contracts and bends outward together with the elastic body 30. As a result, the ultrasonic transducer 33 is bent into an elliptical shape.

Therefore, when a high frequency voltage is applied to the terminal 39 and a high frequency voltage with a phase shift of 90° (1/4 period) is applied to the terminal 40, the voltage applied to each electrostrictive element becomes as shown in Fig. 4. It changes with time, each electrostrictive element expands according to the polarization direction, and the bending deformation state (vibration state) of the vibrator 33 changes continuously. )→(ii)→(iii)
→It becomes as shown in (iv).

This means that when high frequency voltages with different phases are applied to a plurality of electrostrictive elements having positional phases, the vibrating state of the vibrator generates a traveling wave that moves with time and vibrates.

In this example, each electrostrictive element is arranged to have a position phase of 1/4 wavelength of the applied voltage.

FIG. 4 shows the taper 3 of the elastic body 30 in FIG.
The contact state of the rotor 34 inscribed in the rotor 3' is shown broken down into quarter cycles. The point where the two contact each other is the apex of the wave, and in this case, this apex makes half a revolution on the outer peripheral surface of the rotor 34 for one period of vibration.

Note that, as shown in FIG. 5, in the traveling wave due to bending vibration, a longitudinal vibration component (longitudinal wave) appears as the distance from the neutral axis 51 of the elastic body 50 increases, and the longitudinal vibration component (longitudinal wave) appears on the surface 50' of the bending elastic body. Elliptical vibration is formed by combining the and transverse vibration.

Elliptical vibrations due to bending traveling waves are also formed on the inner peripheral surface of the vibrator in the embodiment of this invention,
The rotor 34, which comes into pressure contact with this surface, is driven to rotate by the frictional force.

Also, the elastic body and rotor are in contact at multiple points,
In addition, since the contact point only moves, wear of the contact portion is reduced and durability can be increased compared to conventional piezoelectric motors.

Furthermore, by switching the phase of the high frequency voltage applied to the terminals 40 and 39, the rotation direction of the rotor can be easily switched.

FIG. 6 shows another embodiment of the invention,
An example of a linear motor that converts ultrasonic vibration into linear motion is shown. In the figure, an ultrasonic vibrator 46 is constructed by providing a piezoelectric body 43 on a loop-shaped elastic body 42. One or more elastic bodies 4 are applied to the surface of a plate-like member 41 as a moving body.
2 are pressed into contact with each other, and a piezoelectric body 43 is provided on a part of the surface of the elastic body 42. Corner portions 42' of the elastic body 42 are curved to allow surface waves to propagate. A plurality of electrodes 44, 4 are provided on the surface of the piezoelectric body 43.
4'... are arranged so as to have a phase difference.

When phase-shifted high-frequency voltages are applied to the electrodes 44, 44', a surface wave traveling in one direction is generated on the surface of the elastic body 42.

Since the corner portion 42' of the elastic body has a curved surface shape, this surface wave propagates along the surface, so that the plate member 41 in pressure contact can be driven in the direction of arrow W.

Note that in this case, waves are generated that are an integral multiple of the circumferential length of the surface of the vibrator. By switching the phases of the applied voltages, the plate member 41 can be easily moved in the opposite direction.

Furthermore, since the vibrator and the plate-like member are in contact with each other at the peaks of the plurality of waves, the ultrasonic motor has higher durability than conventional ultrasonic motors.

In addition, although the above embodiment mainly uses an electrostrictive element, it is possible to use an electrostrictive element instead.

(Effects of the Invention) The driving principles and embodiments of the driving method and motor device using ultrasonic vibrations according to the present invention have been described in detail above, but unlike various conventional motor devices, the present invention has An ultrasonic transducer is formed by a plurality of electrostrictive elements and an elastic body arranged so as to have a phase difference, and high frequency voltages with different phases are applied to the electrostrictive elements. By generating a traveling wave capable of forming an elliptical vibration on a predetermined surface, and further placing a moving body in pressure contact with the predetermined surface of the ultrasonic transducer, the moving body is frictionally driven. The present invention is characterized by a driving method and motor device that utilize ultrasonic vibrations.

For this reason, it has the great effects of having strong rotational force and driving force, being small and lightweight, and able to be applied to a variety of applications, being able to easily rotate forward and reverse, and being highly durable.

[Brief explanation of drawings]

Fig. 1 is a partially enlarged perspective view for explaining the operating principle of the present invention, and Figs. be. FIG. 3 is a sectional view showing an example of the pressure regulating mechanism. FIG. 4 is an exploded view showing the state of contact between the vibrator and the rotor, and FIG. 5 is a conceptual diagram showing traveling wave elliptic vibration due to bending vibration. FIG. 6 is a partial perspective view showing an example of a linear motor that converts ultrasonic vibration into linear motion. DESCRIPTION OF SYMBOLS 1, 30... Elastic body, 2... Moving body, 23, 24... Cam, 25... Steel ball, 31... Casing body, 32...
Support member, 33... Vibrator, 33'... Taper, 3
4... Rotor, 35... Rotating shaft, 36... Pressure regulating mechanism, 3
7... Electrostrictive element, 38... Bearing, 39, 40... Terminal,
41... Plate member, 42... Elastic body, 42'... Elastic body corner part, 43... Piezoelectric body, 44, 44'... Electrode,
46...Ultrasonic vibrator.

Claims (1)

[Claims] 1. A moving object is brought into pressure contact with the surface of an elastic body of an ultrasonic transducer in which a plurality of electrostrictive elements are fixed to an elastic body, and high frequency voltages having temporally different phases are applied to the parallel electrostrictive elements. A method for driving a motor device using ultrasonic vibration, characterized in that a traveling wave forming an elliptical vibration is generated on the surface of the elastic body of the ultrasonic vibrator to frictionally drive a moving body. 2 Consists of an ultrasonic transducer with a plurality of electrostrictive elements fixed to an elastic body, and a moving body brought into pressure contact with the surface of the elastic body of this ultrasonic transducer, and the electrostrictive elements arranged in parallel have temporally different phases. A motor device using traveling wave friction drive, characterized in that a moving object is driven by applying a high frequency voltage. 3. The motor device according to claim 2, wherein the elastic body is a ring-shaped bending elastic body. 4. The motor device according to claim 2, wherein the elastic body is a loop-shaped elastic body, and a plate-like body is brought into pressurized contact with the surface of the elastic body.