JPH08223947A - Ultrasonic motor - Google Patents

Abstract

PURPOSE: To obtain a highly efficient high-output ultrasonic motor in which the machining work of protrusion is facilitated. CONSTITUTION: The ultrasonic motor comprises an elastic body 11 for generating a vibration wave on the driving plane, and a mover having a driven plane coming into frictional contact with the driving plane of the elastic body 11 and being shifted by the vibration wave. A large number of fine grooves 11b are made, with a substantially constant interval, in the driving plane of the elastic body 11 in the direction substantially perpendicular to the moving direction of the mover 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic motor having an improved sliding surface between an elastic body and a relative motion member.

[0002]

2. Description of the Related Art FIG. 7 is a perspective view showing an example of a conventional ultrasonic motor, and FIG. 8 is an enlarged perspective view partially showing a stator of an ultrasonic motor according to a conventional example. The conventional ultrasonic motor includes a stator 1 and a mover 2. The stator 1 is
It is composed of an elastic body 11 and a piezoelectric body 12 bonded to the elastic body 11 and excited by applying a drive signal. The mover 2 includes a mover base material 21 and a sliding member 22 attached to the mover base material 21 and in contact with the drive surface of the elastic body 11 of the stator 1.

The elastic body 11 has a large number of protrusions 11 on the driving surface side.
a is molded (see Japanese Examined Patent Publication No. 1-40597), and the projection 11a provides a vibration expanding effect. As shown in FIG. 8, the projection 11a has a large projection height L and a small projection width W, whereby a force in the driving direction can be efficiently obtained. In the projection 11a, even if the projection height L is increased, the rigidity of the entire stator 1 is increased unless the projection width W is decreased to some extent. Therefore, the energy required to generate vibration is increased. Will be at a disadvantage.

[0004]

However, in the above-mentioned conventional ultrasonic motor, the stator 11 has the base thickness L0 and the protrusion 11 when the stator 11 is actually processed into an ideal protrusion shape.
As shown in FIG. 8, deep groove processing was performed on the stator blank material having a thickness obtained by adding the height L of “a”, which was difficult to process. Further, since the end surface of the protrusion 11a needs to be finished to a flatness of 1 μm or less by post-processing, the protrusion height is limited to about 2 to 4 times the base thickness L0.

On the other hand, the stator has a plastic layer formed on the end surface without protrusions (Japanese Patent Laid-Open No. 63-220773).
No.), an end surface of the protrusion is machined into an arc shape or chamfered (Japanese Patent Laid-Open No. 63-283475), and various combinations of sliding members have been proposed.
However, in reality, none of the above proposals has the effect of increasing the height of the protrusion shape and reducing the groove width as described above. As described above, the conventional stator 11
Due to processing restrictions, the shape of the protrusion cannot be made thin and high, and the design for improving the performance has a very small degree of freedom. An object of the present invention is to provide an ultrasonic motor having a large output and a high efficiency with a simple configuration.

[0006]

In order to solve the above-mentioned problems, the invention of claim 1 includes an elastic body which generates a vibration wave on a driving surface and a driven surface which makes frictional contact with the driving surface of the elastic body. In an ultrasonic motor having a relative movement member that moves by the vibration wave, at least one of the driving surface of the elastic body and the driven surface of the relative movement member is provided with a fine groove. There is.

According to a second aspect of the present invention, in the ultrasonic motor according to the first aspect, a plurality of the fine grooves are provided at substantially constant intervals. According to a third aspect of the present invention, in the ultrasonic motor according to the first or second aspect, the fine grooves are provided in a direction substantially orthogonal to a moving direction of the relative motion member.

[0008]

According to the present invention, since the fine grooves are provided on at least one of the driving surface of the elastic body and the driven surface of the relative motion member,
Due to the edge effect of the fine groove, the frictional force can be adjusted by utilizing the catching of the driven surface of the relative motion member, and the frictional driving can be efficiently performed. Therefore, the ultrasonic motor can improve the driving torque and the driving efficiency without designing the projection shape, which is difficult to process.

[0009]

【Example】

(First Embodiment) Hereinafter, the embodiments will be described in more detail with reference to the drawings. 1 is a perspective view partially showing a first embodiment of an ultrasonic motor according to the present invention, FIG.
[FIG. 6] is a diagram for explaining fine grooves of the ultrasonic motor according to the first embodiment. In addition, in the first and second embodiments, portions having the same functions as those of the above-described conventional example are denoted by the same reference numerals, and duplicate description will be appropriately omitted. In the stator 1A of this embodiment, the lower side (piezoelectric body side) of the annular elastic body 11 is continuous, and the protrusion (small vibrating piece) 1 is formed on the upper side (mover side).
1a is formed.

A plurality of fine grooves 11b are provided on the upper surface of the projection 11a at substantially constant intervals. The fine grooves 11b are provided in a direction substantially orthogonal to the moving direction of the mover (relative movement member) 2. This fine groove 11b
The groove depth Y is preferably about 0.1 to 5 μm, and can be machined by a dicing saw or a fine electric discharge machine. It is preferable that the sliding surface after machining be mirror-finished.

As shown in FIG. 2B, the fine grooves 11b are in contact with each other so that the respective concave and convex portions bite into the sliding member 22, so that the frictional force becomes large. Thus, the fine groove 1
1b plays a role of obtaining an optimum coefficient of friction with the sliding member 22, and has an effect that slippage is unlikely to occur and driving efficiency is good. The protrusion 11a is for increasing the amplitude of the elliptical movement, and the fine groove 11a
It is different from the function and action of b.

In this embodiment, the stator 1A is made of S.
US304, an annular stator blank with a diameter of about 70 mm, has a protrusion width W of about 1 mm and a protrusion height L of about 3 m.
m projections 11a were formed. And the fine groove 11b is
In the circumferential direction of the upper surface of the protrusion 11a, about 50 grooves were formed at regular intervals within a range of 1 mm in width by a dicing saw. As a result, the fine grooves 11b have an angular pitch θ of about 1 minute in the diameter direction, a groove width X of about 20 μm, and a groove depth Y ′ of about 5.
A 0 μm U-shaped groove was formed. After processing, the sliding surface was mirror-lapped to finally set the groove depth Y to about 40 μm.

This stator 1A was combined with a mover 2 in which a plastic sliding member 22 was adhered to a mover base material 21 made of aluminum, an annular ultrasonic motor was assembled, and a drive experiment was conducted. Compared to the stator without the fine grooves 11b, the torque and efficiency are about 10 each.
%, An improvement of about 3% was observed.

(Second Embodiment) FIG. 3 is a perspective view partially showing a second embodiment of the ultrasonic motor according to the present invention. In the stator 1B of the second embodiment, the fine groove 1 is provided only in a portion of the protrusion 11a in the diametrical direction, which is necessary for sliding.
1c is formed. In this embodiment, the fine groove 11c is used.
The processing time can be shortened and the cost can be reduced.

In the second embodiment, except that the groove length of the fine groove 11c is set to Z = about 2 mm, the same one as the first embodiment is manufactured, and the same driving experiment is conducted. Similar performance improvements were seen. Moreover, the processing time has been greatly reduced.

(Third Embodiment) FIG. 4 is a diagram showing a third embodiment of the ultrasonic motor according to the present invention.
4A is a front view, FIG. 4B is a side view, FIG. 4C is a plan view, and FIG. 4D is a bottom view. The third embodiment is a modified degenerate vertical L1-bending B4 mode flat plate type ultrasonic motor, which is composed of an elastic body 111 and a piezoelectric body 112. The elastic body 111 has protrusions 111a and 111b formed on one surface of a rectangular flat plate and the piezoelectric body 11 on the other surface.
2a and 112b are attached. In this ultrasonic motor, the high frequency voltage A, is applied to the two piezoelectric bodies 112a and 112b.
By applying B, a composite vibration of the vibration in the longitudinal L1 mode and the vibration in the bending B4 mode is generated, and the protrusion 111
Elliptic motion occurs at the tips of a and 111b. This ultrasonic motor has a relative motion member 1 by a pressure member (not shown).
02, and relative movement between the relative movement member 102 and the relative movement member 102 occurs.

The ultrasonic motor of this embodiment has the protrusion 1
A fine groove 111b is formed on the lower surface of 11a, and the fine groove 111b plays a role of obtaining an optimum frictional force between the fine groove 111b and the relative moving member 102, and it is difficult for slipping to occur and the driving efficiency is good. Has the effect.

(Fourth Embodiment) FIGS. 5 and 6 are views showing a fourth embodiment of an ultrasonic motor according to the present invention. FIG. 5 is a sectional view and FIG. 6 shows a stator. It is a perspective view. Fourth
Is an ultrasonic motor of longitudinal / torsional vibration type, in which the stator 201 is excited by a drive signal, and piezoelectric bodies 204 and 205 which are electro-mechanical conversion elements for converting electric energy into mechanical energy. , Those piezoelectric bodies 20
4, 205 are joined together, and the piezoelectric bodies 204, 20
The elastic body 2 in which a driving force is generated on the driving surface D by the primary longitudinal vibration and the primary torsional vibration generated by the excitation of No. 5
It is composed of 02 and 203.

The elastic bodies 202 and 203 are members each having a shape obtained by vertically dividing a thick-walled cylinder into two, and the piezoelectric bodies 204 and 205 are sandwiched between the divided surfaces. Piezoelectric body 204, 2
Reference numeral 05 denotes a total of four layers, and two layers of the piezoelectric body 204
Is a piezoelectric body for torsional vibration with a large piezoelectric constant d ₁₅ , and the remaining two layers of piezoelectric body 205 are piezoelectric bodies for longitudinal vibration with a large piezoelectric constant d ₃₁ .

The elastic bodies 202 and 203 have through holes 202b and 203b formed substantially in the center in the height direction in parallel with the stacking direction of the piezoelectric bodies 204 and 205 (see FIG. 6).
The elastic bodies 202 and 203 have holes 202b and 203, respectively.
By being fixed with the bolt 213 and the nut 214 by using b, the piezoelectric bodies 204 and 205 are sandwiched and fixed to the fixed shaft 207 inserted at the center in the axial direction.

The mover 206 is a mover base material 206-1.
And a sliding member 206 that contacts the drive surface D of the stator 201.
-2, and is positioned with respect to the fixed shaft 207 by a positioning member 208 such as a bearing fitted to the inner peripheral portion. The mover 206 is pressed against the drive surface D of the stator 201 by a pressing member 209 such as a disc spring, a spring spring, or a leaf spring.

The fixed shaft 207 penetrates through hollow portions 202a and 203a formed in the axial direction of the elastic bodies 202 and 203, and fixes the stator 1 formed of the elastic bodies 202 and 203, and at the same time, moves the movable body 206. To position in the radial direction. The fixed shaft 207 has a threaded portion formed at the tip thereof and is provided with an adjusting member 210 such as a nut for adjusting the amount of pressure applied by the pressure member 209. When the piezoelectric bodies 204 and 205 are excited by application of a drive signal, torsional vibration and longitudinal vibration are generated in the elastic bodies 202 and 203, respectively. When the resonance frequencies of the longitudinal vibration and the torsional vibration are substantially equal to each other, the longitudinal vibration and the torsional vibration simultaneously occur (degenerate), an elliptical motion is generated on the driving surface D, a driving force is generated, and the mover 206 rotates.

In the ultrasonic motor of this embodiment, fine grooves 201b are formed on the drive surface D of the elastic bodies 202 and 203, and the fine grooves 201b obtain an optimum frictional force between the fine groove 201b and the moving element 206. This has the effect of preventing slippage and improving drive efficiency.

(Other Embodiments) The present invention is not limited to the embodiments described above, and various modifications and changes are possible, which are also within the scope of the present invention. For example, the present invention is not limited to the ultrasonic motors described in the above embodiments, but can be similarly applied to other ultrasonic motors such as impact type motors. Further, in the first to third embodiments, the fine groove is provided on the end surface of the protrusion, but it may be provided directly on the driving surface as in the fourth embodiment. Further, although the fine grooves have been described in the example provided on the stator side, they can be provided on the mover side.

[0025]

As described above in detail, according to the present invention, the friction effect is adjusted by utilizing the catching effect of the driven surface of the relative motion member due to the edge effect of the fine groove, and the friction driving is efficiently performed. Therefore, high torque and high efficiency, which cannot be realized only by improving the shape of the protrusion, were obtained.

[Brief description of drawings]

FIG. 1 is a perspective view partially showing a first embodiment of an ultrasonic motor according to the present invention.

FIG. 2 is a diagram illustrating fine grooves of the ultrasonic motor according to the first embodiment.

FIG. 3 is a perspective view partially showing a second embodiment of the ultrasonic motor according to the present invention.

FIG. 4 is a front view, a side view, a plan view and a bottom view showing an ultrasonic motor according to a third embodiment of the present invention.

FIG. 5 is a sectional view showing a fourth embodiment of the ultrasonic motor according to the present invention.

FIG. 6 is a perspective view showing a stator of an ultrasonic motor according to a fourth embodiment.

FIG. 7 is a perspective view showing an example of a conventional ultrasonic motor.

FIG. 8 is an enlarged perspective view partially showing a stator of an ultrasonic motor according to a conventional example.

[Explanation of symbols]

 1, 1A, 1B Stator 11 Elastic body 11a Protrusion 11b Fine groove 12 Piezoelectric element 2 Moving element 21 Moving element base material 22 Sliding member

Claims (3)

[Claims] 1. An ultrasonic motor comprising: an elastic body that generates a vibration wave on a drive surface; and a relative motion member that has a driven surface that makes frictional contact with the drive surface of the elastic body and that moves by the vibration wave. The ultrasonic motor according to claim 1, wherein fine grooves are provided on at least one of the driving surface of the elastic body and the driven surface of the relative motion member. 2. The ultrasonic motor according to claim 1, wherein the fine grooves are provided in plural at substantially constant intervals. 3. The ultrasonic motor according to claim 1 or 2, wherein the fine grooves are provided in a direction substantially orthogonal to a moving direction of the relative motion member. .