JPH07143771A - Ultrasonic motor and its manufacture - Google Patents

Abstract

PURPOSE:To provide a structure where the degradation of performance due to the distortion in machining is prevented during operation. CONSTITUTION:The ultrasonic motor comprises an elastic body 11, piezoelectric elements 12, 13 coupled with the elastic body 11 to cause harmonic oscillation in longitudinal and bending oscillation modes, a member 16 making a relative motion to the elastic member 11, and one or more output take-out member 14, 15 disposed between the elastic body 11 and the relative motion member 16 and causes relative motion between the elastic body 11 and the relative motion member 16 through elliptical motion produced by the combined oscillation of the longitudinal and bending oscillation modes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic motor for producing a driving force by generating an elliptical motion in a rod-shaped elastic body, and more particularly,
The present invention relates to an ultrasonic motor that drives a longitudinal vibration mode and a bending vibration mode in two phases.

[0002]

2. Description of the Related Art FIG. 4 is a diagram showing a conventional example of a linear ultrasonic motor. In a conventional linear ultrasonic motor, a vibrating transformer 102 is arranged on one end side of a rod-shaped elastic body 101 and a vibrating transformer 103 is arranged on the other end side.
Each of the transformers 102, 103 includes a vibrator 102a, 103
a is joined. An alternating voltage is applied from the oscillator 102b to the vibrator 102a for vibration to vibrate the rod-shaped elastic body 101, and this vibration propagates through the rod-shaped elastic body 101 to become a traveling wave. Due to this traveling wave, the rod-shaped elastic body 10
The moving body 104 that is brought into pressure contact with 1 is driven.

On the other hand, the vibration of the rod-shaped elastic body 101 is transmitted to the vibrator 103a through the vibration damping transformer 103, and the vibrator 103a converts the vibration energy into electric energy. The load 103b connected to the vibrator 103a consumes the electric energy to absorb the vibration. This vibration damping transformer 103 suppresses the reflection of the end surface of the rod-shaped elastic body 101, and the rod-shaped elastic body 1
The generation of standing waves of 01 eigenmodes is prevented.

The linear type ultrasonic motor shown in FIG.
The length of the rod-shaped elastic body 101 is required only for the moving range of 04, and the whole of the rod-shaped elastic body 101 has to be vibrated, so that the device becomes large and the standing wave of the eigenmode is generated. In order to prevent this, there has been a problem that the vibration damping transformer 103 and the like are required.

In order to solve such problems, various self-propelled ultrasonic motors have been proposed.
The "degenerate vertical L1-bending B4 mode flat plate motor" described in "222 Piezoelectric linear motor for moving optical pickup" in "Proceedings of Dynamics Symposium on Electromagnetic Force" is known.

FIG. 5 is a schematic view showing a conventional example of a modified degenerate vertical L1-bending B4 mode flat plate motor.
5A is a front view, FIG. 5B is a side view, and FIG. 5C is a plan view. The elastic body 1 includes a rectangular flat plate-shaped base portion 1a,
Protrusions 1b, 1 formed on one surface of the base 1a
and c. The piezoelectric elements 2 and 3 are elastic bodies 1.
Is an element that is attached to the other surface of the base portion 1a to generate a longitudinal vibration L1 mode and a bending vibration B4 mode. The protrusions 1b and 1c of the elastic body 1 are provided at antinodes of the bending vibration B4 mode generated in the base portion 1a, and are pressed against a guide rail (not shown).

[0007]

However, the above-mentioned FIG.
The motor has a structure in which the protrusions 1b and 1c for taking out the driving force are integrally formed on a part of the elastic body 1.
There is a problem in that the parts other than the protrusions 1b and 1c need to be largely shaved off by mechanical processing in the manufacturing stage, and the stress due to processing is generated as processing strain during use and the performance is reduced.

An object of the present invention is to solve the above-mentioned problems and to provide an ultrasonic motor having a structure in which performance deterioration due to processing strain does not occur during use.

[0009]

In order to solve the above-mentioned problems, the first means for solving the problems of the ultrasonic motor according to the present invention is an elastic body (11) and the elastic body which is connected to the elastic body. An electromechanical conversion element (12, 13) that harmonically generates a longitudinal vibration mode and a bending vibration mode, a relative motion member (16) that performs relative motion between the elastic body, and the elastic body. Relative movement between the elastic body and the relative movement member is caused by an elliptical movement that is located between the relative movement member and is joined to the elastic body and is generated by a combined vibration of the longitudinal vibration mode and the bending vibration mode. And one or more output extraction members (14, 15) for causing movement.

A second solving means of the ultrasonic motor according to the present invention is characterized in that, in the ultrasonic motor of the first solving means, the output extracting member is arranged at an antinode position of the bending vibration mode. can do.

A third solving means of the ultrasonic motor according to the present invention is characterized in that, in the ultrasonic motor of the first or second solving means, the output extracting member is made of a material different from that of the elastic body. be able to.

A fourth solving means of the ultrasonic motor according to the present invention is the ultrasonic motor according to any one of the first and second solving means, wherein a plurality of the output extracting members are provided. All or part of the material may be different.

A first solution of the method of manufacturing an ultrasonic motor according to the present invention is the method of manufacturing an ultrasonic motor according to any one of the first to fourth solutions, wherein the elastic body is rod-shaped or plate-shaped. And a joining step of joining the output extracting member to the elastic body.

A second solution of the method for manufacturing an ultrasonic motor according to the present invention is the method for manufacturing an ultrasonic motor according to the first solution, wherein a plurality of types of the output extracting member having different dimensions and / or materials are used. It can be characterized in that it is prepared and selectively attached to the elastic body.

[0015]

According to the present invention, since the elastic body and the output extracting member are separate members, output reduction due to processing strain does not occur during use.

[0016]

Embodiments Embodiments will be described in more detail below with reference to the drawings. FIG. 1 is a schematic diagram showing a first embodiment of an ultrasonic motor according to the present invention. Piezoelectric elements 12 and 13 for generating a longitudinal vibration L1 mode and a bending vibration B4 mode are arranged in the elastic body 11. The function of each element is similar to that shown in FIG. 5 described above.
In this embodiment, the piezoelectric elements 12 and 13 are polarized as shown in FIG. 1C, and two-phase input voltages A and B as shown in FIG.

On the lower surface of the elastic body 11, two output extracting members 14 and 15 are arranged. In this embodiment, the material of the output extracting members 14 and 15 is the same metal as the elastic body 11, and the elastic body 11 and the output extracting members 14 and 15 are the same.
1A is machined separately as shown in FIG. 1A (processing step), and is joined with an epoxy adhesive as shown in FIG. 1B (joining step). This allows
Unlike the ultrasonic motor of FIG. 5, it is not necessary to largely scrape off parts other than the protrusions by machining in the manufacturing stage, and the stress due to machining does not occur as processing distortion during use and the performance does not deteriorate. . Moreover, since the material of the output extraction members 14 and 15 is the same metal as the elastic body 11, there is no deformation due to temperature change.

As shown in FIG. 1, this ultrasonic motor is
By applying high-frequency voltages A and B to the two piezoelectric elements 12 and 13, a composite vibration of bending vibration and longitudinal vibration is caused, thereby causing elliptical motion at the tips of the output extracting members 14 and 15, and driving. It is configured to generate force. Here, G is the ground. The two piezoelectric elements 12 and 13 are polarized so that the polarities thereof are in the same direction, and the high frequency voltages A and B have a temporal phase difference of π / 2. The polarizations of the two piezoelectric elements 12 and 13 may be opposite to each other.

FIG. 2A shows changes with time of the two-phase high frequency voltages A and B input to the ultrasonic motor at t1 to t9. The horizontal axis of FIG. 2A shows the effective value of the high frequency voltage. FIG. 2B shows how the cross section of the ultrasonic motor is deformed, and shows a temporal change (t1 to t9) of the bending vibration generated in the ultrasonic motor. FIG. 2C shows how the cross section of the ultrasonic motor is deformed, and shows the temporal changes (t1 to t9) of the longitudinal vibration generated in the ultrasonic motor. FIG. 2D shows the output extracting member 14 of the ultrasonic motor,
Change of elliptic motion generated at 15 and 15 (t1 to t9)
Is shown.

Next, the operation of the ultrasonic motor of this embodiment will be described for each time change (t1 to t9). Time t
2, the high frequency voltage A generates a positive voltage, and the high frequency voltage B similarly generates the same positive voltage, as shown in FIG. As shown in FIG. 2B, the bending motions due to the high frequency voltages A and B cancel each other out, and the mass point Y1
And Z1 have zero amplitude. Further, as shown in FIG. 2C, the longitudinal vibrations due to the high frequency voltages A and B are generated in the extending direction. The mass points Y2 and Z2 show the maximum elongation around the node X, as indicated by the arrow. As a result,
As shown in (D), the above-mentioned both vibrations are combined, and the mass point Y1
The synthesis of the motion of Y and Y2 becomes the motion of the mass point Y, and the synthesis of the motion of the mass points Z1 and Z2 becomes the motion of the mass point Z.

At time t2, as shown in FIG. 2 (A), the high frequency voltage B becomes zero and the high frequency voltage A generates a positive voltage. As shown in FIG. 2 (B), a bending motion is generated by the high frequency voltage A, the mass point Y1 oscillates in the positive direction, and the mass point Z1 oscillates in the negative direction. Further, as shown in FIG. 2 (C), longitudinal vibration due to the high frequency voltage A occurs, and the mass points Y2 and Z2 contract more than at time t1. As a result, as shown in FIG. 2D, the above-mentioned both vibrations are combined, and the mass Y
And Z move clockwise relative to the time t1.

At time t3, as shown in FIG. 2 (A), the high frequency voltage A generates a positive voltage, and the high frequency voltage B similarly generates the same negative voltage. As shown in FIG. 2 (B), the bending motions due to the high frequency voltages A and B are combined and amplified, and the mass point Y1 is amplified in the positive direction more than at the time t2, showing the maximum positive amplitude value. Mass point Z1 is time t2
It is amplified in the negative direction more than, and shows the maximum negative amplitude value. Further, as shown in FIG. 2C, the longitudinal vibrations due to the high frequency voltages A and B cancel each other out, and the mass points Y2 and Z2
And return to their original positions. As a result, as shown in FIG. 2D, both of the above vibrations are combined, and the mass points Y and Z move clockwise relative to the time t2.

At time t4, as shown in FIG. 2A, the high frequency voltage A becomes zero, and the high frequency voltage B generates a negative voltage. As shown in FIG. 2 (B), a bending motion is generated by the high frequency voltage B, and the amplitude of the mass point Y1 is lower than that at the time t3, and the amplitude is lower than that at the mass point Z1 time t3. Further, as shown in FIG. 2C, longitudinal vibration due to the high frequency voltage B is generated, and the mass points Y2 and Z2 contract.
As a result, as shown in FIG. 2 (D), both of the above vibrations are combined, and the mass points Y and Z move clockwise relative to the time t3.

At time t5, as shown in FIG. 2 (A), the high frequency voltage A generates a negative voltage, and similarly, the high frequency voltage B generates the same negative voltage. As shown in FIG. 2B, the bending motions due to the high frequency voltages A and B cancel each other out, and the masses Y1 and Z1 have zero amplitude. Also, FIG.
As shown in (C), the longitudinal vibration due to the high frequency voltages A and B is generated in the contracting direction. The mass points Y2 and Z2 show the maximum contraction around the node X, as indicated by the arrow. As a result, as shown in FIG. 2 (D), both of the above vibrations are combined, and the mass points Y and Z move clockwise relative to the time t4.

As the time t6 to t9 changes,
Flexural vibrations and longitudinal vibrations are generated in the same manner as the above-described principle, and as a result, as shown in FIG. 2D, the mass points Y and Z move clockwise and make an elliptic motion. Based on the above principle, this ultrasonic motor is configured to generate an elliptic motion at the tips of the output extracting members 11a and 11b to generate a driving force. Therefore, when the tips of the output extraction members 14 and 15 are pressed against the stator 19, the elastic body 11 is self-propelled with respect to the fixed portion 19.

FIG. 3 shows a second ultrasonic motor according to the present invention.
It is a schematic diagram showing an example of. The parts having the same functions as those of the first embodiment described above are designated by the same reference numerals, and the duplicated description will be omitted. In the second embodiment, the output extracting members 14 and 15 are made of a material different from that of the elastic body 11. Here, the elastic body 11 is made of an aluminum alloy, and the output extraction members 14, 15 are made of nickel. Therefore, a lightweight ultrasonic motor having a hard sliding surface can be obtained.

Further, the output extracting member 15 (the output extracting member 1
4 is also the same), the convex portion 15a is provided,
It is adapted to fit into the recess 11a formed in the elastic body 11. At this time, the output extraction member 15 shown in FIG.
It is also possible to prepare those having different heights such as A, and select and attach the output extraction member according to the device to be incorporated.

The present invention is not limited to the embodiments described above, and various modifications and changes are possible, which are also included in the present invention. The materials of the elastic body 11 and the output extracting members 14 and 15 are not limited to those described above. For example, the elastic body 11 can be made of stainless steel and the output extracting members 14 and 15 can be made of resin having high abrasion resistance. In this way, an ultrasonic motor with good durability can be obtained. As a resin with high abrasion resistance,
For example, a material containing 80% (W) of tetrafluoroethylene, 15% (W) of glass fiber, and 5% (W) of molybdenum disulfide can be given.

The material of the output extracting members 14 and 15 is
It is not necessary to use the same material. For example, when the forward path travels slowly for precise positioning, and the return path returns quickly for recovery, when the speeds differ depending on the direction of travel, the material of the output extraction members 14 and 15 should be changed. It is preferable to make them different. Further, the output extraction members 14 and 15 may be joined to the elastic body 11 by screwing or the like, in addition to adhesion and fitting.

[0030]

As described above in detail, according to the present invention, since the elastic body and the output extracting member are separate members, the output reduction due to the processing strain does not occur during use. effective.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a first embodiment of an ultrasonic motor according to the present invention.

FIG. 2 is a diagram illustrating a driving operation of the ultrasonic motor according to the first embodiment.

FIG. 3 is a schematic diagram showing a second embodiment of the ultrasonic motor according to the present invention.

FIG. 4 is a diagram showing a conventional example of a linear ultrasonic motor.

FIG. 5 is a schematic view showing an example of a modified degenerate vertical L1-bending B4 mode flat plate motor.

[Explanation of symbols]

 11 Elastic Body 12, 13 Piezoelectric Element 14, 15 Output Extraction Member 16 Fixed Part

Claims (6)

[Claims] 1. An elastic body, an electromechanical conversion element which is coupled to the elastic body, and which causes a longitudinal vibration mode and a bending vibration mode in the elastic body in a harmonic manner, and a relative amount between the elastic body. Relative motion member performing a different motion, located between the elastic body and the relative motion member, joined to the elastic body, by the elliptic motion caused by the combined vibration of the longitudinal vibration mode and the bending vibration mode, An ultrasonic motor, comprising: one or more output extracting members that cause relative movement between the elastic body and the relative movement member. 2. The ultrasonic motor according to claim 1, wherein the output extracting member is arranged at an antinode position of the bending vibration mode. 3. The ultrasonic motor according to claim 1, wherein the output extracting member is made of a material different from that of the elastic body. 4. The ultrasonic motor according to any one of claims 1 to 3, wherein a plurality of the output extraction members are provided, and all or some of them are different materials. Ultrasonic motor characterized by. 5. An ultrasonic motor manufacturing method for manufacturing the ultrasonic motor according to claim 1, further comprising a processing step of processing the elastic body into a rod shape or a plate shape, A joining step of joining the output extracting member to an elastic body. 6. The method of manufacturing an ultrasonic motor according to claim 5, wherein a plurality of types of the output extraction member having different dimensions and / or different materials are prepared and selectively attached to the elastic body. Method of manufacturing ultrasonic motor.