JPH0880079A - Ultrasonic motor and device having ultrasonic motor - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] To provide an ultrasonic motor having a structure that can be applied by a low-cost method for spraying a sliding material made of an abrasion-resistant organic material only on the driving surface of a vibrator. [Structure] A vibrator that is driven by a piezoelectric element 11 and a moving element that is in pressure contact with an elastic body 9 that constitutes the vibrator and that is driven in a predetermined direction are provided. In an ultrasonic motor that forms a friction surface by forming a wear-resistant coating layer on the surface, the vibrator has a fastening portion for sandwiching and fixing the electro-mechanical energy conversion element to the elastic member, Even if the fastening portion is arranged in a region where the friction surface is projected in a direction perpendicular to the friction surface and the sliding material is blown from a direction perpendicular to the friction surface, the sliding material vibrates. The elastic body 9 forming the child is prevented from adhering to the fastening portion.

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 forming a rod-shaped ultrasonic motor, and an ultrasonic motor having such a structure. The present invention relates to a device having a drive source.

[0002]

2. Description of the Related Art Progressive vibration is generated on the surface of an elastic body to which an electro-mechanical energy conversion element such as a piezoelectric element is fixed,
An ultrasonic motor configured to convert the vibration energy into a continuous mechanical movement in one direction and to extract the vibration energy has been put into practical use by the applicant of the present invention, and is now installed in an optical device such as a camera and widely used in general. It is like this.
Conventionally known rotary ultrasonic motors include ring-type and disk-type types and rod-type types. The ring-type and rod-type types are the optical devices manufactured by the applicant. It is installed.

A conventional example of a rod-shaped 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 source is composed of a piezoelectric element group 11 sandwiched and held between elastic bodies 9 and 10 made of metal or the like. Has been done. The elastic body 9 is an element group 1 that is pressed against a bolt-shaped head 5b that serves as a skeletal member of the motor.
It is composed of 1 and 1. The elastic body 9 is screwed onto the large-diameter screw portion 5a of the bolt-shaped support rod 5 serving as a skeletal member of the motor, and the elastic body 10 is elastically pushed by being pressed by the large-diameter head portion 5b of the support rod 5. The piezoelectric element group 11 is sandwiched and held between the body 9 and the body 9. Reference numeral 2 denotes a rotor (that is, a mover) arranged so as to face the tip surface of the elastic body 9, and a thin spring portion 2a that is axially flexible is formed on the tip surface of the rotor 2.
The spring portion 2a is pressed against the tip surface of the elastic body 9. An output gear 4 is fitted and fixed to the rotor 2, and the gear 4
Is fitted to 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 5c near the tip of the support rod 5. A spring bearing 7 is fitted and fixed to the inner peripheral portion of the rotor 2, and a spring portion 2 a of the rotor 2 is provided between the tip of the spring bearing 7 on the oscillator side and the end of the output gear 4. A pressure spring 8 for pressing the tip end surface of the elastic body 9 is arranged.

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 resonance detection. It consists of Each piezoelectric element 11
The a to 11e are polarized with left and right being inverted with respect to 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 phase A, the piezoelectric element expands and contracts to cause the vibrator 1 to move in the direction 1 horizontal to the paper surface.
Next bending natural vibration is excited. Further, when an AC electric field is applied only to the B phase, it vibrates in the direction perpendicular to the paper surface.

When the horizontal vibration excited by the A phase and the 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. A circular motion of occurs. Since the elastic body 9 has the circumferential groove 9a for expanding the displacement, the swinging motion as shown in FIG. 3 occurs at the tip of the elastic body 9.

Seen from the friction surface (upper surface of the vibrator), this vibration corresponds to one traveling wave. This oscillator has 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 flange 6 attached to the tip of the support rod 5 is designed as an integral system so that the eigenmode of the vibrator is designed so that the vibration amplitude of the flange 6 becomes extremely small. , The support loss is very small compared to the ring type 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, like the annular ultrasonic motor. Further, the rotor main ring has a sufficiently large inertial mass and is designed so that the vibration is not excited by the exciting force of the vibrator.

[0010]

One of the disadvantages of ultrasonic motors is that they have a short service life. The cause is
The ultrasonic motor obtains the driving force by the frictional force.

That is, in order to obtain a high torque, it is necessary to obtain a large frictional force, but if slippage occurs at this time, a large amount of energy is consumed on the friction surface, and wear proceeds. In the known ultrasonic motor, a wear-resistant sliding material is used for the mutual friction surface between the rotor and the vibrator, and wear of this sliding material never ends the life of the ultrasonic motor.

Although many studies have recently been made on this sliding material, many of them use organic materials and have a long life.

For example, epoxy resins, polyimides, polyamides, polyamideimides, silicone resins, and mixtures thereof have a large friction constant and low wear. When PTFE, potassium titanate, carbonic acid fiber or the like is added to these, the friction constant is slightly lowered, but the wear is further reduced.

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 against vibration strain, it is necessary to form it separately. However, it is troublesome and costly to stick a sheet of organic material, so we would like to adopt the coating method. Moreover, spray painting is the easiest and lowest cost. Here, the problem is the organic material that adheres to other than the friction surface.

As described above, the elastic body 9 has a spiral fastening portion, but if it is attached to this, it may hinder the assembly of the vibrator, such as a change in screw size or a decrease in screw strength. Here, the fastening portion refers to a screw portion, a press-fitting fitting eye portion, a caulking coupling fastening portion, and the like. The above-mentioned circumstances are the same in these fastening structures. By the way, even if it is not the fastening portion, the side surface of the vibrator is greatly distorted due to the bending vibration. Therefore, if the organic material adheres to the organic material, the internal attenuation thereof causes an increase in energy loss, resulting in deterioration of motor efficiency. Therefore, it takes time and effort to apply a spray coating after applying 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 by a low cost method such as spraying only on the driving surface of an elastic body constituting a vibrator. To provide.

A second object of the present invention is to provide an apparatus using an ultrasonic motor as a drive source for realizing the above first object.

[0018]

Means and Actions for Solving the Problems First of the Invention
According to a first aspect of the present invention, a vibrator driven by an electro-mechanical energy conversion element and an elastic body forming the vibrator are pressure-contacted and driven in a predetermined direction. In an ultrasonic motor having a moving element, and forming a wear resistant coating layer on a contact surface of the elastic body with the moving element to form a friction surface, the vibrator includes the electro-mechanical energy conversion element. It has a fastening portion for sandwiching and fixing it to the elastic member, and the fastening portion is arranged in a region where the friction surface is projected in a direction perpendicular to the friction surface.

In this structure, when a sliding member made of, for example, an organic material having abrasion resistance is sprayed from a direction perpendicular to the friction surface of the elastic member constituting the vibrator, the sliding member forms the vibrator. It does not adhere to the fastening part of the elastic body.

With this structure, it is possible to prevent adverse effects such as fastening failure due to the sliding material adhering to the screw holes of the fastening portion when assembling the vibrator.

Another structure for achieving the first object of the present invention is to provide a vibrator driven by an electro-mechanical energy conversion element and an elastic body constituting the vibrator as described in claim 2. An ultrasonic motor having a moving element which is brought into pressure contact and driven in a predetermined direction, and a friction-resistant surface is formed by forming a wear-resistant coating layer on a contact surface of the elastic body with the moving element; Is characterized in that members constituting the vibrator are arranged in a region where the friction surface is projected in a direction perpendicular to the friction surface.

With this structure, when a sliding material made of, for example, an organic material having abrasion resistance is sprayed from a direction perpendicular to the friction surface of the elastic member forming the vibrator, the sliding material forms the vibrator. It does not adhere to the peripheral wall surface of the elastic body.

That is, the side wall surface of the elastic member constituting the vibrator has a large distortion due to bending deformation during driving, but the upper surface of the elastic member forming the friction surface has a relatively small distortion. Therefore, by increasing the area of the upper surface of the elastic member that constitutes the friction surface so that the member that constitutes the vibrator is housed within the area where the upper surface is projected from above, the sliding material is sprayed from above and painted. However, the sliding material does not adhere to other than the upper surface of the elastic member.

The structure for realizing the second object of the present invention is, as described in claim 3, an apparatus having an ultrasonic motor using the ultrasonic motor according to claim 1 or 2 as a drive source.

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

[0026]

【Example】

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
The motor driving principle and the basic configuration are the same as those in FIG. 4, except that the vibrator 9 is also provided with a contact spring 9b on the elastic body 9.
Be provided. The gear 4 and the support rod 5 slide directly, and the ball bearing is abolished. Further, it is different that a sliding member 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, but since the elastic body 9 is entirely included in the region where the friction surface is projected from above, a large strain is generated by vibration 9c,
The organic material does not adhere to the side surface of the oscillator such as 9d, and the internal loss of the oscillator hardly increases by coating.

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

When a coating method such as brush coating is adopted instead of spraying, even if the coating material drips due to gravity, it does not adhere to other portions according to the present embodiment, which is effective.

(Second Embodiment) FIG. 5 shows a second embodiment of the present invention. The elastic body 9 which constitutes the vibrator of the rod-shaped ultrasonic motor of the present embodiment has a friction surface inner diameter 9 as compared with a conventional elastic body.
Since g is small, the sliding member 12 does not adhere to the screw fitting portion 9e having a diameter larger than the inner diameter 9g, so that the initial screw dimension does not change and the assembly is possible. Although only organic materials have been a problem so far, the present embodiment achieves the same effects and objects even when an inorganic material (for example, tungsten carbide, nickel, hard alumite, etc.) is spray-coated (including thermal spraying, etc.).

In this embodiment, only the case where the inner diameter of the friction surface is small is shown, but in addition to this, the outer diameter of the friction surface is made larger than that of the conventional elastic body so that it slides on the side surface of the elastic body. By preventing the material from adhering, it is possible to prevent an increase in internal loss of the vibrator.

(Third Embodiment) FIG. 6 shows a third embodiment of the present invention. In the elastic body 9 which constitutes the vibrator of the rod-shaped ultrasonic motor of the present embodiment, 9f is a circumferential protrusion, and when a sliding material 12 made of an organic material is applied to this, it rises like a kamaboko.
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 the present embodiment, the electro-mechanical energy conversion element group 11 forming a vibrator excites torsional and vertical vibrations. Then, by appropriately providing the time phase difference between both vibrations, an elliptic motion is generated on the upper surface of the elastic body 9, and if the rotor 2 is pressed against this, frictional force is generated.
The ultrasonic motor in which the rotor rotates is a known technique. The present invention can be applied even if it is based on such a driving principle.

That is, the side surface of the elastic body 9 is greatly distorted by torsion and vertical vibration, and it is not preferable that the sliding member 12 made of an organic material adheres to the side surface of the elastic body 9. Since no deformation such as bending has occurred and the strain is relatively small, the sliding material 12 is applied to this upper surface by spraying. In addition, the inner surface has a screw for clamping, but it is difficult to attach it to the inner surface. Therefore, the elastic body 9
The outer diameter of the taper is tapered and the projection 9h is provided on the inner diameter side to prevent the sticking to these.

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

In the rod-shaped ultrasonic motor of this 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 sandwiching body portion 13, and one of the sandwiching body portion 13 is arranged. The support rod 5 is screwed to the elastic body 9 provided on the end face, whereby the piezoelectric element group 11 is sandwiched and fixed by the elastic body 9, the sandwiching body portion 13 and the support rod 5 to form a vibrator. The elastic body 9 is formed in a cap shape, and its peripheral wall portion 9i covers the outer periphery of the sandwiching 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 on one end side is brought into pressure contact with the moving body 2 as shown in FIG. ), 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 joint portion during application.

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

In the figure, reference numeral 60 denotes the ultrasonic motor shown in FIG. 6, and constituent elements of the motor 60 are indicated by the same reference numerals as those in FIG. Reference numeral 50 denotes a lens held by a lens barrel 51 of the optical device, 55 a fixed barrel fixed to the optical device and supporting the lens barrel 51 by a helicoid 56 so as to be rotatable and axially movable. A motor mounting plate fastened to the flange 20 of the motor 60, 53 is an equipment-side driven gear meshed with the output gear 19 of the motor 60 and driven to rotate by the gear 19, and 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 rotationally driven, and the lens barrel 51 is rotated via the gear 53 and a gear mechanism (not shown). Lens 5
The lens barrel 51 holding 0 is moved axially while rotating around the optical axis.

[0041]

According to the invention described in claim 1, when a sliding material made of, for example, an organic material having abrasion resistance is sprayed from a direction perpendicular to the friction surface of the elastic member constituting the vibrator, The sliding material does not adhere to the fastening portion of the elastic body that constitutes the vibrator.

With this structure, it is possible to prevent adverse effects such as fastening failure due to the sliding material adhering to the screw holes of the fastening portion when assembling the vibrator.

According to the second aspect of the present invention, when the abrasion-resistant sliding member made of, for example, an organic material is sprayed from the direction perpendicular to the friction surface of the elastic member constituting the vibrator,
The sliding material does not adhere to the peripheral wall surface of the elastic body that constitutes the vibrator.

That is, the side wall surface of the elastic member constituting the vibrator has a large distortion due to bending deformation during driving, but the upper surface of the elastic member forming the friction surface has a relatively small distortion. Therefore, by increasing the area of the upper surface of the elastic member that constitutes the friction surface so that the member that constitutes the vibrator is housed within the area where the upper surface is projected from above, the sliding material is sprayed from above and painted. However, the sliding material does not adhere to other than the upper surface of the elastic member.

Therefore, according to the first and second aspects of the invention, a vibrator having high wear resistance can be obtained by a simple processing step, and an ultrasonic motor having a long life and high efficiency can be provided at a low cost. be able to.

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

[Brief description of drawings]

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

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

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

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

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

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

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

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

FIG. 9 is a vertical cross-sectional view of a part of an optical device 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 ... Moving element 5, 15 ... Support rod 4, 19 ... Output gear 6, 20 ... Flange 8, 18 ... Rotor pressure spring 12, 17, 23, 35 ... Covering material 36 ... Resin sheet 50 ... Lens 51 ... Lens barrel 55 ... Fixed barrel 56 ... Helicoid 60 ... Ultrasonic motor 52 ... Motor mounting Plate 53 ... Driven gear

Claims (3)

[Claims] 1. A mover of an elastic body, comprising: a vibrator driven by an electro-mechanical energy conversion element; and a mover which is brought into pressure contact with an elastic body forming the vibrator and is driven in a predetermined direction. In an ultrasonic motor that forms a friction surface by forming a wear resistant coating layer on the contact surface with the child, the vibrator has a fastening portion for sandwiching and fixing the electro-mechanical energy conversion element to the elastic member. The ultrasonic motor is characterized in that the fastening portion is arranged in a region where the friction surface is projected in a direction perpendicular to the friction surface. 2. A movement of the elastic body, comprising a vibrator driven by the electro-mechanical energy conversion element, and a mover which is in pressure contact with an elastic body forming the vibrator and is driven in a predetermined direction. In an ultrasonic motor that forms a friction surface by forming a wear-resistant coating layer on the contact surface with the child, the vibrator is arranged in a region where the friction surface is projected in a direction perpendicular to the friction surface. An ultrasonic motor characterized in that constituent members are arranged. 3. An apparatus having an ultrasonic motor using the ultrasonic motor according to claim 1 or 2 as a drive source.