JP3179662B2 - Ultrasonic motor and device having ultrasonic motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic motor, and more particularly to a structure capable of suitably applying a sliding material to an elastic body of a vibrator constituting a rod-shaped ultrasonic motor. The present invention relates to an apparatus using a driving source.

[0002]

2. Description of the Related Art Progressive vibration is generated on the surface of an elastic body to which an electromechanical energy conversion element such as a piezoelectric element is fixed,
An ultrasonic motor configured to convert the vibration energy into continuous mechanical movement in one direction and take it out has been put to practical use by the present applicant, and is currently mounted on optical equipment such as a camera and widely used in general. It has become.
Conventionally known rotary ultrasonic motors include an annular type and a disk type, and a rod type, and the annular type and the rod type are used in optical devices manufactured by the present applicant. It is installed.

A conventional example of a rod-type ultrasonic motor will be described below as a prior art of the present invention.

In the rod-shaped ultrasonic motor shown in FIG. 3, a vibrator 1 serving as a vibration energy generating source is composed of a piezoelectric element group 11 held between elastic bodies 9 and 10 made of metal or the like. Have been. The elastic body 9 has a bolt-shaped head serving as a frame member of the motor, and an element group 1 pressed by 5b.
1 and 1. The elastic body 9 is screwed onto a large-diameter threaded portion 5a of a bolt-shaped support rod 5 serving as a frame member of the motor, and the elastic body 10 is elastically pressed by a large-diameter head 5b of the support rod 5. The piezoelectric element group 11 is held between the body 9 and the body. Reference numeral 2 denotes a rotor (that is, a moving element) disposed so as to face the distal end surface of the elastic body 9, and a thin spring portion 2 a that can bend in the axial direction is formed on the distal end surface of the rotor 2.
The spring portion 2 a is pressed against the distal end surface of the elastic body 9. An output gear 4 is fitted and fixed to the rotor 2.
Is fitted on the outer ring of the ball bearing 3. The inner ring of the ball bearing 3 is fitted and fixed to a motor mounting flange 6, and the flange 6 is fitted and fixed to a portion 5 c near the tip of the support rod 5. A spring receiver 7 is fitted and fixed to an inner peripheral portion of the rotor 2. A spring portion 2 a of the rotor 2 is attached between the vibrator-side tip of the spring receiver 7 and an end of the output gear 4. A pressurizing spring 8 for pressing against the distal end surface of the elastic body 9 is disposed.

FIG. 4 shows the arrangement of the piezoelectric element group 11 provided in the vibrator 1, the polarization pattern, and the configuration of the piezoelectric element. The piezoelectric element group 11 includes A-phase piezoelectric elements 11a and 11b to which an A-phase drive signal is applied, B-phase piezoelectric elements 11c and 11d to which a B-phase drive signal is applied, and an S-phase piezoelectric element 11e for detecting resonance. It is composed of Each piezoelectric element 11
The electrodes a to 11e are polarized right and left inverted around the center line, and an electrode plate (not shown) is inserted between the piezoelectric elements 11a to 11e. The driving principle of the ultrasonic motor is as follows.

When an AC electric field is applied only to the A-phase, the vibrator 1 is placed on the vibrator 1 in a direction parallel to the plane of FIG.
The next bending natural vibration is excited. Also, when an AC electric field is applied only to the B phase, it vibrates in a direction perpendicular to the paper surface.

When a horizontal vibration excited by the A-phase and a vertical vibration caused by the B-phase are applied with a phase difference of 90 degrees in time, the vibrator is rotated clockwise or counterclockwise with respect to the longitudinal axis. Circular motion occurs. Since the elastic body 9 has a circumferential groove 9a for expanding the displacement, a swinging motion as shown in FIG.

When viewed from the friction surface (upper surface of the vibrator), this vibration corresponds to one traveling wave. This vibrator has a spring 2
When the rotor 2 having “a” is brought into pressure contact, the rotor 2 comes into contact with the elastic body 9 only at one place near the wave front, and rotates in the direction opposite to the traveling wave. The output is taken out by a gear 4 fitted to the outer ring of the rotor 2 and the ball bearing 3.

In the rod-shaped ultrasonic motor, the eigenmode of the vibrator is designed so that the vibration amplitude of the flange 6 is extremely small, since the flange 6 attached to the tip of the support rod 5 is also an integral system. The supporting loss is much smaller than that of a ring-shaped vibrator supported by a vibration absorbing material such as felt. The spring portion 2a of the rotor 2 has a natural frequency sufficiently higher than the vibration frequency of the vibrator and is designed to follow the vibration, similarly to the annular ultrasonic motor. Further, the rotor main ring has a sufficiently large inertial mass and is designed so that vibration is not excited by the exciting force of the vibrator.

[0010]

One of the disadvantages of the ultrasonic motor is that it has a short durability life. The cause is
An ultrasonic motor obtains a driving force by a frictional force.

That is, in order to obtain a high torque, it is necessary to obtain a large frictional force. However, if slippage occurs at this time, a large amount of energy is consumed on the frictional surface, so that abrasion proceeds. In a known ultrasonic motor, a wear-resistant sliding material is used for a mutual friction surface between the rotor and the vibrator, and the wear of the sliding material will last the life of the ultrasonic motor.

Although many studies have been made on the sliding material recently, many of those using an organic material have a long life.

For example, epoxy resins, polyimides, polyamides, polyamide imides, silicone resins, and mixtures thereof have a large friction constant and low wear. Further, when PTFE, potassium titanate, carbonated fiber or the like is added to these, the friction constant is slightly lowered but the wear becomes lower.

Therefore, these organic materials are applied to the friction surface. However, since the vibrator material is made of metal or the like so as to have a low loss with respect to vibration strain, it is necessary to form the vibrator separately. However, sticking an organic material sheet is time-consuming and costly, so we would like to adopt a coating method. Moreover, spray painting is the easiest and the lowest cost. Here, what matters is an organic material that adheres to a portion other than the friction surface.

As described above, the elastic body 9 has a helical fastening portion, but if attached to the elastic body 9, it may hinder assembly of the vibrator, such as a change in screw dimensions and a decrease in screw strength. Here, the term "fastening portion" refers to a threaded portion, a press-fit fitting portion, a crimping fastening portion, or the like. The situation described above is the same in these fastening structures. By the way, even if it is not a fastening part, since the vibrator side face generates a large distortion due to the bending vibration, if an organic material adheres to the side, internal loss will increase energy loss and lead to deterioration of motor efficiency. Therefore, it is time-consuming to spray-coat after forming a mask or the like and then remove the mask.

A first object of the present invention is to provide an ultrasonic motor having a structure in which a sliding member made of a wear-resistant organic material can be applied to only a driving surface of an elastic body constituting a vibrator by a low cost method such as a spraying method. Is to provide.

A second object of the present invention is to provide an apparatus which uses an ultrasonic motor as a drive source and realizes the first object.

[0018]

According to a first aspect of the present invention, there is provided an electric vehicle comprising:
-Bullets whose traveling wave is excited by the mechanical energy conversion element
Body and electro-mechanical energy conversion element sandwiched between elastic bodies
A vibrator consisting of a fastening part for fixing and an elastic body
A moving element which is brought into pressure contact and driven in a predetermined direction by a traveling wave
And a wear-resistant coating layer on the contact surface of the elastic body with the moving element
Friction surface, the fastening part and the peripheral wall of the vibrator
Placed in the area projected the surface perpendicular to the friction surface
It is characterized by the following.

In this configuration, when a wear-resistant sliding material made of, for example, an organic material is sprayed from a direction perpendicular to the friction surface of the elastic member constituting the vibrator, the sliding material forms the vibrator. It does not adhere to the fastening portion and the peripheral wall surface of the vibrator .

With this structure, the elastic body constituting the friction surface
The area on the upper surface of the
The peripheral wall of the vibrator and the fastening part fit within the projected area of the surface
By spraying the sliding material from above by painting
Also, the sliding material does not adhere to portions other than the upper surface of the elastic body.
Therefore, when assembling the vibrator, etc.,
Prevents adverse effects such as poor fastening due to the adhesion of sliding material to
Can be stopped, and the size increases with the bending vibration of the vibrator.
Sliding material may adhere to the peripheral wall of
This can prevent the energy loss from increasing.

The first other configurations to achieve the object of the present invention, as described in claim 2, electro - mechanical energy varying
Body and electro-mechanical device in which traveling wave is excited by exchange element
Tightening to fix the energy conversion element to the elastic body
Pressure contact between the vibrator consisting of the joint and the peripheral wall of the elastic body.
A moving element driven in a predetermined direction by a traveling wave;
Consists of a wear-resistant coating layer on the peripheral wall contacting the vibrator
It has a friction surface, and the elastic body itself
Placed in the area projected in the direction perpendicular to the surrounding wall
And features.

In this configuration, when a wear-resistant sliding material made of, for example, an organic material is sprayed from a direction perpendicular to the axial direction of the vibrator, the sliding material forms the vibrator. Elastic body
It does not adhere to parts other than the peripheral wall .

According to this configuration, the peripheral wall surface of the elastic body
Increased area and projected the peripheral wall from outside of this peripheral wall
By making the elastic body itself fit in the area, the surrounding wall surface
Even if the sliding material is sprayed and painted from the outside of the
No sliding material adheres to the surface. Therefore vibration
Sliding material adheres to screw holes, etc. in the fastening part when assembling
Can prevent adverse effects such as fastening failures
And the bending vibration of the vibrator other than the peripheral wall of the elastic body.
Due to the adhesion of the sliding material to the part where
An increase in energy loss can be prevented.

According to a third aspect of the present invention, there is provided an apparatus having an ultrasonic motor driven by the ultrasonic motor according to the first or second aspect.

With this configuration, an ultrasonic motor having excellent durability can be used as a driving source.

[0026]

【Example】

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
The principle of driving the motor and the basic configuration are the same as those in FIG.
Is provided. The gear 4 and the support rod 5 slide directly, and the ball bearing is eliminated. Further, the difference is that a sliding material 12 which is an organic material is applied to the upper surface of the elastic body 9 including the vibrator friction surface.

FIG. 2 is an enlarged view of the elastic body 9 in this embodiment.
Shown in The organic material is spray-painted from above the friction surface. However, since the elastic body 9 is entirely contained in a region where the friction surface is projected from above, a large distortion 9c,
The organic material does not adhere to the side surface of the vibrator such as 9d, and the internal loss of the vibrator hardly increases by coating.

Further, since it does not adhere to the screw portion 9e, it is possible to prevent a defective fastening or the like.

It is effective to apply a coating method such as brush coating instead of spraying, because even if a coating material sags due to gravity, it does not adhere to other parts according to this embodiment.

(Second Embodiment) FIG. 5 shows a second embodiment of the present invention. The elastic body 9 constituting the vibrator of the rod-shaped ultrasonic motor of the present embodiment has a friction surface inner diameter 9 as compared with the conventional elastic body.
Since g is small, there is no attachment of the sliding member 12 to the screw fitting portion 9e having a diameter larger than the inner diameter 9g, so that the screw can be assembled without an initial change in screw dimensions. Although only organic materials have been considered so far, the present embodiment achieves the same effects and objects when spray coating (including thermal spraying, etc.) an inorganic material (for example, tungsten carbide, nickel, hard alumite, etc.).

In this embodiment, only the case where the inner diameter of the friction surface is small is shown. In addition to this, the outer diameter of the friction surface is made larger than that of the conventional elastic body, and the sliding surface is moved to the side of the elastic body. By preventing the material from adhering, an increase in the internal loss of the vibrator can be prevented.

(Third Embodiment) FIG. 6 shows a third embodiment of the present invention. In the elastic body 9 constituting the vibrator of the rod-shaped ultrasonic motor according to the present embodiment, reference numeral 9f denotes a circumferential projection, and when a sliding material 12 made of an organic material is applied to the projection, the projection protrudes in a semi-cylindrical shape.
As a result, the edge 2b of the contact spring provided on the rotor 2
Since 2c does not contact the sliding material 12, the sliding material 12 made of an organic material is not damaged and wear can be reduced.

(Fourth Embodiment) FIG. 7 shows a fourth embodiment of the present invention. In the rod-shaped ultrasonic motor of this embodiment, the electromechanical energy conversion element group 11 forming a vibrator excites torsional and vertical vibrations. By appropriately giving a time phase difference between the two vibrations, an elliptical motion is generated on the upper surface of the elastic body 9, and when the rotor 2 is pressed against this, the frictional force causes
The ultrasonic motor in which the rotor rotates is a known technique. The present invention can be applied even with such a driving principle.

That is, the side surface of the elastic body 9 is subjected to a large strain due to torsion and longitudinal vibration, and it is not preferable that the sliding material 12 made of an organic material adheres to the side surface. Since no deformation such as bending occurs and the distortion is relatively small, the sliding material 12 is applied to the upper surface by spraying. Further, although a screw for holding is cut on the inner surface, it is difficult to assemble the screw on the inner surface. Therefore, the elastic body 9
Are tapered, and a protrusion 9h is provided on the inner diameter side, thereby preventing adhesion to these.

(Fifth Embodiment) FIG. 8 shows a fifth embodiment of the present invention.

In the rod-shaped ultrasonic motor according to the present embodiment, the piezoelectric element group 11 is disposed between the large-diameter portion of the support rod 5 having the large-diameter portion and the holding body portion 13, and one of the holding body portions 13 is provided. The support rod 5 is screw-coupled to the elastic body 9 provided on the end face, thereby forming a vibrator in which the piezoelectric element group 11 is clamped and fixed by the elastic body 9, the clamp body 13 and the support rod 5. The elastic body 9 is formed in a cap shape, and its peripheral wall portion 9i covers the outer periphery of the holding body portion 13.

In this vibrator, the other end of the support rod 5 is fixed to a fixing member, and the peripheral wall 9i of the elastic body 9 at one end is brought into pressure contact with the moving body 2 as a driving surface. ), The moving body 2 is intermittently driven by the driving surface that makes a circular or elliptical motion.

Here, the sliding material 12 is applied to the peripheral wall portion 9i of the elastic body 9 by spraying, but the portion where the elastic body 9 is screwed to the support rod 5 is inside the peripheral wall portion 9i.
The sliding material does not adhere to the screw connection portion during application.

(Sixth Embodiment) FIG. 9 is a view showing an optical apparatus incorporating an ultrasonic motor according to the present invention.

In the figure, reference numeral 60 denotes the ultrasonic motor shown in FIG. 6, and the components of the motor 60 are denoted by the same reference numerals as those in FIG. 50 is a lens held in the lens barrel 51 of the optical device, 55 is a fixed tube fixed to the optical device and supporting the lens barrel 51 by a helicoid 56 so as to rotate and move in the axial direction. A motor mounting plate 53 fastened to the flange 20 of the motor 60 meshes with the output gear 19 of the motor 60 and is a driven gear driven by the gear 19 for rotation. A gear 54 is provided coaxially with the gear 53. It is a slip clutch. When the motor 60 is driven, the gear 19 is rotated, the driven gear 53 on the device side is driven to rotate, and the lens barrel 51 is rotated via the gear 53 via a gear mechanism (not shown). Lens 5
The lens barrel 51 holding 0 is moved in the axial direction while rotating about the optical axis.

[0041]

According to the first aspect of the present invention, when a wear-resistant sliding member made of, for example, an organic material is sprayed from a direction perpendicular to the friction surface of the elastic body constituting the vibrator,
The sliding material does not adhere to the fastening portion that forms the vibrator and the peripheral wall surface of the vibrator .

With this configuration, when assembling the vibrator or the like, it is possible to prevent adverse effects such as poor fastening due to the attachment of the sliding material to the screw holes or the like of the fastening portion. Also, vibration
Vibrator peripheral wall causing large distortion due to bending vibration of transducer
Increased energy loss due to adhesion of sliding material to surface
Can be prevented.

[0043] According to the invention described in claim 2, the transducer
When a sliding material made of, for example, an abrasion-resistant material such as an organic material is sprayed from a direction perpendicular to the axial direction, the sliding material does not adhere to portions other than the peripheral wall surface of the elastic body constituting the vibrator. .

With this configuration, when assembling the vibrator, it is possible to prevent adverse effects such as poor fastening due to a sliding material adhering to a screw hole or the like of the fastening portion. It is possible to prevent an increase in energy loss due to the attachment of the sliding material to a portion where distortion occurs due to the bending vibration of the vibrator.

Therefore, according to the first or second aspect of the present invention, a highly wear-resistant vibrator can be obtained by a simple machining process, and a long-life and efficient ultrasonic motor is provided at low cost. be able to.

According to the third aspect of the present invention, an ultrasonic motor having excellent durability can be used as a drive source.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an ultrasonic motor according to a first embodiment of the present invention.

FIG. 2 is a partially enlarged view of the embodiment shown in FIG.

FIG. 3 is a longitudinal sectional view of a conventional ultrasonic motor.

FIG. 4 is a diagram showing a configuration and an arrangement of a piezoelectric element group used in the ultrasonic motor in FIG. 3;

FIG. 5 is a partial schematic longitudinal sectional view of an ultrasonic motor according to a second embodiment of the present invention.

FIG. 6 is a partial schematic longitudinal sectional view of an ultrasonic motor according to a third embodiment of the present invention.

FIG. 7 is a longitudinal sectional view of a fourth embodiment of the present invention.

FIG. 8 is a longitudinal sectional view of a fifth embodiment of the present invention.

FIG. 9 is a longitudinal sectional view of a part of an optical apparatus equipped with the ultrasonic motor of the present invention.

[Explanation of symbols]

1, 22, 24 ... vibrator 11, 27 ... piezoelectric element group 9, 10, 13, 14, 26, 28 ... elastic body 2, 16 ... rotor 29 ... mover 5, 15 ... support rod 4, 19 ... output gear 6, 20 ... Flange 8, 18 ... Rotor pressurizing spring 12, 17, 23, 35 ... Coating material 36 ... Resin sheet 50 ... Lens 51 ... Lens barrel 55 ... Fixed cylinder 56 ... Helicoid 60 ... Ultrasonic motor 52 ... Motor mounting Plate 53: driven gear

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H02N 2/00

Claims (3)

(57) [Claims] (1) An electric-mechanical energy conversion element
Elastic body excited by line waves and the electro-mechanical energy
A fastening portion for sandwiching and fixing the conversion element to the elastic body;
A vibrator made of
A movable element driven in a predetermined direction by the
Friction surface consisting of wear-resistant coating layer on contact surface with moving element
Wherein the fastening portion and the peripheral wall surface of the vibrator are
Arranged in the area where the friction surface is projected in the direction perpendicular to the friction surface
An ultrasonic motor characterized by being performed . 2. An electro-mechanical energy conversion element,
Elastic body excited by line waves and the electro-mechanical energy
A fastening portion for sandwiching and fixing the conversion element to the elastic body;
Before contact with the vibrator made of
A moving element driven in a predetermined direction by the traveling wave;
Wear-resistant coating on the contact surface of the peripheral wall of the conductive body with the vibrator
A friction surface composed of a layer, wherein the elastic body itself has the elasticity
Projecting the peripheral wall surface of the body in a direction perpendicular to the peripheral wall surface of the elastic body.
An ultrasonic motor, wherein the ultrasonic motor is disposed in a region where the ultrasonic motor is located. 3. An apparatus having an ultrasonic motor driven by the ultrasonic motor according to claim 1.