JPH01318564A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To simplify the structure of an apparatus and to facilitate the regulation of a frictional force by supporting a fixed disc through a plurality of piezoelectric ceramics and by arranging a rotatable disc in a state where the rotatable disc is opened at a specified distance from the fixed disc and faces the same. CONSTITUTION:An ultrasonic motor is composed of a top-opened and bottomed box 1 equipped with a base 11 on the underside, a plurality of piezoelectric ceramics 2 arranged an interior parts in the box, a fixed disc 3 fastened to the upper end of the ceramics, and a rotatable disc 4 journaled by the box 1. There bars are used in the piezoelectric ceramics 2 and respective ceramics 2a-2c are arranged and fixed in a state where they are opened at an angle of 120 deg. to the base 11. The upper and of the ceramics is fitted with the fixed disc 3 and a driving shaft 41 is integrally projected from the rotatable disc 4. Thus, piezoelectric ceramics 2a stretch by application of voltage to function as the biasing force (horizontal component) of the rotatable disk 4 in the direction of rotation, etc., and the disc 4 turns by a pressure welding frictional force.

Description

[Detailed description of the invention] (b) Industrial application fields The present invention relates to an ultrasonic motor.

(b) Conventional technology Figures 5, 6, and 7 show conventional ultrasonic morphs. Figure 5 is a schematic configuration diagram of the ultrasonic morph, and Figure 6 is the generation of traveling waves in an ultrasonic motor. FIG. 7 is an explanatory diagram showing the state, and FIG. 7 is an explanatory diagram showing the principle of object movement by ultrasonic morph.

The conventional ultrasonic morph has an elastic body 5 as shown in FIG.
1 and a large number of piezoelectric ceramics 52 surrounding the lower surface of an elastic body 51. A large number of piezoelectric ceramics 52 of 1/2 wavelength attached to the lower surface of the elastic body 51 have a two-layer structure, an upper layer and a lower layer, and the piezoelectric ceramics 52 arranged below are each shifted by 1/4 wavelength. It is arranged as follows. Therefore, each of the piezoelectric ceramics 52 superimposed in the upward and downward directions, that is, the upper piezoelectric ceramic 52 receives a wave of sin ω, and the lower piezoelectric ceramic 52 receives a wave of CO2.
It is set to apply a wave of 5ωt.

In this ultrasonic morph, a traveling wave is generated in the elastic body 51 by the electric field as shown in FIG. That is, a sine wave (solid line wave in FIG. 6) and a cosine wave (broken line wave in FIG. 6) are generated. This traveling wave (maximum energy) circulates around the elastic body 51. Therefore, when a moving object 53 is placed on top of an elastic body 51 as shown in FIG. 7, the moving object 53 receives the traveling wave generated by applying an electric field, and the moving object 53 moves in the direction in which the traveling wave travels due to frictional force. Go in the opposite direction. That is, the moving object 53 rotates on the elastic body 51.

(c) Problems to be Solved by the Invention The conventional ultrasonic motor described above rotates a moving object by applying an electric field to piezoelectric ceramics and generating traveling waves in an elastic body. For this reason, an elastic body is required to generate traveling waves (the piezoelectric ceramics must be polarized and bonded with their positions shifted by 1/4 wavelength, making the structure complicated). Further, the adjustment of the frictional force between the moving object and the elastic body is performed mechanically by the pressing force of the moving object.Therefore, there is a disadvantage that the adjustment of the frictional force cannot be easily carried out.

An object of the present invention is to solve the above problems and provide an ultrasonic morph with a simple structure and easy adjustment of frictional force.

(d) Means and operation for solving the problem In order to achieve this object, the ultrasonic motor of the present invention has the following configuration.

The ultrasonic motor consists of a plurality of piezoelectric ceramics arranged at a predetermined angle, one end of which is fixed to a substrate, the other end fixed to a fixed disc, and a rotating disc equipped with a drive shaft and rotatably supported. A voltage is sequentially applied to the piezoelectric ceramics in a time-sharing manner so that the contact point between the fixed disk and the rotating disk moves in the circumferential direction. It is configured as follows.

In an ultrasonic motor having such a configuration, one piece of piezoelectric ceramic, for example, three pieces, each having a certain length with respect to the substrate, is used.
They are arranged with each 20 degree angle open. and,
A fixed disk is fixed to the negative end of these three pieces of piezoelectric ceramic. In other words, the fixed disk is supported by three wooden pillars (piezoelectric ceramics). A rotatable disk (rotating disk) facing the fixed disk is normally spaced apart from each other by a certain distance.

Now, when a voltage is sequentially applied to each piezoelectric ceramic in a time-sharing manner, the piezoelectric ceramic receives the voltage and expands. As the piezoelectric ceramic expands, the portion of the fixed disk corresponding to the expanded piezoelectric ceramic is lifted and comes into contact with the rotatable disk located above. At this time, an upward pressing force acts on the rotatable disk. Due to this upward pressure contact force, the rotatable disc moves slightly upward at this pressure contact point, but the rotatable disc is supported by a bearing and is prevented from moving up or down.

Therefore, the rotatable disc can absorb this pressing force. This upward pressing force acts as a pressing force in the rotational direction of the rotatable disc, that is, a horizontal component force, and the rotatable disc Rotates due to pressure friction force. Thus, by sequentially applying a voltage to each piezoelectric ceramic, the pressure contact point between the fixed disk and the rotatable disk changes, that is, the pressure contact point goes around once, so the rotatable disk rotates. do.

(E) Embodiment FIG. 1 is a sectional view of a main part showing a specific embodiment of the ultrasonic morph according to the present invention.

The ultrasonic morph consists of a box 1 with an open bottom and a substrate (base member) 11 on the bottom surface, a plurality of piezoelectric ceramics 2 arranged inside the box 1, and the piezoelectric ceramics 2.
It is composed of a fixed disc 3 fixed to the upper end of the housing 1, and a rotatable disc 4 supported on the housing 1.

In the embodiment, three rods are used as the piezoelectric ceramics 2, and each of the piezoelectric ceramics 2a, 2b, and 2c is arranged at an angle of 120 degrees with respect to the substrate 11, and its base end is fixed. The piezoelectric ceramic 2 having a certain length is a laminated type made by laminating thin plates of a material having a piezoelectric effect, for example, PZT (zircon titanate), and is a thin, inexpensive commercially available product. These piezoelectric ceramics 2a, 2b.

2c has a property of being mechanically strained, that is, elongated by the application of voltage. These piezoelectric ceramics 2a, 2b,
At the upper end of 2c is attached a fixed disk 3 with a constant diameter.

In other words, the fixed disk 3 has three pillars (piezoelectric ceramics).
It is fixedly supported by 2a, 2b, and 2C.

In the embodiment, the rotatable disk 4 is a rotatable disk having the same diameter as the fixed disk 3, and has a drive shaft (rotation transmission shaft) 41 integrally protruding from the center of the plane. This drive shaft 41 is supported by a bearing 13 provided in the upper opening 12 of the box 1 .

This rotatable disk 4 is arranged opposite to the fixed disk 3 with a predetermined distance (a small gap) between them.

In the ultrasonic motor having such a configuration, the fixed disk 3 and the rotatable disk 4 are normally spaced apart from each other by a small constant distance.

The ultrasonic morph is driven by each piezoelectric ceramic 2a, 2b.
, 2C by sequentially applying voltages. Now, when a voltage is applied to the piezoelectric ceramic 2a, the piezoelectric ceramic 2a that receives the applied voltage expands. As the piezoelectric ceramics 2a expands, the portion of the fixed disk 3 corresponding to the expanded piezoelectric ceramics 2a is lifted and comes into contact with the rotatable disk 4 located above [second
(See Figure (A)) At this time, an upward pressing force (pressing contact point A) acts on the rotatable disc 4. Due to this upward pressing force, the rotatable disc 4 moves slightly upward in this pressing area, but the rotatable disc 4 is supported by a bearing 13 and is prevented from moving up or down. Therefore, the rotatable disk 4 can completely absorb this pressing force, and this upward pressing force acts as a pressing force in the rotational direction of the rotatable disk 4, that is, as a horizontal component force, The rotatable disk 4 is rotated by pressure friction force. Next, a voltage is applied to the piezoelectric ceramic 2b as shown in FIG. 2(B). As a result, the piezoelectric ceramic 2b expands, and the portion of the fixed disk 3 corresponding to the expanded piezoelectric ceramic 2b is lifted and comes into contact with the rotatable disk 4 located on the opposite side. The pressing force caused by the contact acts on the rotatable disc 4 as a horizontal force, as described above, and the rotatable disc 4 rotates due to the pressing friction force. Thereafter, by applying a voltage to the piezoelectric ceramics 2c, the rotatable disk 4 is similarly rotated.

Thus, by sequentially applying a voltage to each piezoelectric ceramic 2a, 2b12C, and continuing to repeatedly apply this voltage (by shifting the phase by 120 degrees, that is, by applying time-divided voltages) As shown in FIG. ) 4 rotates.

When adjusting the frictional force between the fixed disk 3 and the rotatable disk 4, °ζ is adjusted to This can be dealt with by applying an offset voltage. In other words, when the facing distance between the fixed disk 3 and the rotatable disk 4 is too wide as shown in FIG. , each piezoelectric ceramic is extended to a certain length, and the facing distance between the fixed disk 3 and the rotatable disk 4 is set small.

By setting this gap setting state as a normal setting and sequentially applying a voltage to each piezoelectric ceramic 2a, 2b, and 2c, the pressure friction force between the fixed disk 3 and the rotatable disk 4 can be easily adjusted. .

Although the embodiment shows an example in which three piezoelectric ceramics 2 are used, the present invention is not limited to this, and for example, six piezoelectric ceramics or 360 pieces of piezoelectric ceramics may be arranged at equal angles in a circle. . As the number of piezoelectric ceramics 2 increases, smoother rotational force of the rotatable disk 4 can be obtained.

(F) Effects of the Invention In this invention, as described above, a fixed disk is supported by a plurality of piezoelectric ceramics, and a rotatable disk is disposed facing the fixed disk with a predetermined path 81 open. Therefore, by sequentially applying a voltage to each piezoelectric ceramic, the pressure contact point between the fixed disk and the rotatable disk can be moved and rotated, and the rotatable disk can be rotated by the pressure contact friction force.

Therefore, I'Ii! using vibration waves as in the past! Unlike the rotation method using frictional force, there is no need for an elastic body that generates vibration waves, and complicated structures such as the arrangement of piezoelectric ceramics can be eliminated. Further, the pressure friction force between the rotatable disc and the fixed disc can be adjusted very easily. Furthermore, since the piezoelectric ceramic is a laminated type and can be used as a commercially available thin product, it is inexpensive and has excellent effects such as the ability to make the motor itself thin, achieving the purpose of the invention.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of the main parts showing the ultrasonic motor of the embodiment, Fig.
Figure (Δ) is an explanatory diagram showing a state in which a voltage is applied to piezoelectric ceramics, Figure 2 (B) is an explanatory diagram showing a state in which a voltage is applied to piezoelectric ceramics, and Figure 3 is an explanatory diagram showing a state in which a voltage is applied to piezoelectric ceramics. An explanatory diagram showing the movement of the pressure contact point with the flexible disk, Fig. 4 (A
) is an explanatory diagram showing the facing distance between the fixed disc and the rotatable disc, and Fig. 4 (B) shows the application of an offset voltage to the piezoelectric ceramics to reduce the facing distance between the fixed disc and the rotatable disc. An explanatory diagram showing the set state, FIG. 5 is a schematic configuration diagram showing a conventional ultrasonic motor, FIG. 6 is an explanatory diagram showing a traveling wave of an ultrasonic motor since IRT, and FIG. 7 is an explanatory diagram showing a conventional ultrasonic motor. FIG. 2 is an explanatory diagram showing the principle of object movement/υJ by an ultrasonic motor. 2: Piezoelectric ceramics, 3: Fixed disk, 4: Rotatable disk. Figure 1 Figure 2 (A) \11 Figure 2 ('B'') Figure 3 Figure 4 (A) Figure 4 (B) Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] (1) One end of a plurality of piezoelectric ceramics, each arranged at a predetermined angle, is fixed to a substrate and the other end is fixed to a fixed disk, and a rotating disk equipped with a drive shaft and rotatably supported is fixed to the substrate. arranged opposite to the fixed disc with a predetermined interval,
An ultrasonic motor configured to sequentially apply a voltage to the piezoelectric ceramic in a time-sharing manner so that a contact point between the fixed disk and the diversion disk moves in the circumferential direction.