JP2002034272A - Ultrasonic motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic motor capable of the easy and complete fixing of a vibration attenuation member for reducing objectionable vibration. SOLUTION: A vibration control rubber 15 for reducing objectionable vibration is fitted so as not to get out of a through-hole 14d provided at a prescribed part in the circumferential direction of a rotor 12. It is thus possible to attenuate the objectionable vibration with a thin-wall part 14 while the vibration is being transmitted from the rotating shaft to the outer periphery of the rotor 12 even if impulsive vibration (objectionable vibration) is generated between a load and the rotating shaft or between the rotating shaft and the rotor 12 due to rapid fluctuations in driving force at the time of starting or stopping the motor.

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 a structure for reducing unnecessary vibration.

[0002]

2. Description of the Related Art In an ultrasonic motor, for example, a piezoelectric element is fixed to a lower surface of a vibrating portion provided on the outer periphery of a stator, and a rotor connected to a vibrating portion of the stator in a flange shape on a rotating shaft is applied. It is configured to be brought into pressure contact with a pressure member. When a predetermined high-frequency drive voltage is applied to the piezoelectric element, the piezoelectric element vibrates, and a traveling wave vibration is generated in a vibrating portion of the stator based on the vibration. With this traveling wave oscillation,
The frictional force between the stator and the rotor causes the rotor and the rotating shaft to rotate.

When a load is driven using such an ultrasonic motor, when the driving force fluctuates abruptly when the load is started or stopped, the distance between the load and the rotating shaft,
Impact vibration (unnecessary vibration) occurs between the rotating shaft and the rotor. Such unnecessary vibration propagates from the rotating shaft side of the rotor to the outer peripheral side, and further propagates from the outer peripheral portion of the rotor to the vibrating portion of the stator. Problems such as unevenness, reduced output, and generation of abnormal noise (noise) have occurred.

[0004] A technique for solving such a problem is disclosed in Japanese Patent Application Laid-Open No. 7-250488.
In the ultrasonic motor disclosed in this publication, a substantially U-shaped groove having an opening directed to the inner peripheral side is formed over the entire outer periphery of the rotor (rotor), and an elastic member made of a rubber-based material is formed in the groove. A plurality are inserted at predetermined positions in the entire circumference or in the circumferential direction. That is,
The elastic member attenuates unnecessary vibrations propagated from the rotating shaft side of the rotor to the outer peripheral portion and further to the stator, so as to suppress adverse effects on traveling wave vibration generated in the stator.

[0005]

However, in the ultrasonic motor disclosed in the above publication, since the elastic member is merely inserted into the substantially U-shaped groove, there is a possibility that it cannot be fixed securely. Therefore,
It is conceivable that the elastic member is fixed by using an adhesive in order to ensure the fixing of the elastic member. However, there is a problem that it takes time until the adhesive is dried and the fixing cannot be easily performed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to provide an ultrasonic motor capable of easily and reliably fixing a vibration damping member for reducing unnecessary vibration. Is to provide.

[0007]

According to a first aspect of the present invention, a rotor is pressed against a stator having a piezoelectric element to generate traveling wave vibrations based on driving of the piezoelectric element. In the ultrasonic motor, the rotor is rotated by the traveling wave vibration to rotate the rotating shaft, the rotor is provided with a through hole at a predetermined position in a circumferential direction, and the vibration damping member is fitted and fixed to the through hole so as not to come out. Is done.

According to a second aspect of the present invention, in the ultrasonic motor according to the first aspect, the vibration damping member has a projection inserted into the through hole, and the projection is inserted into the through hole. Later, by heating the tip of the projection, it is deformed so as not to come out and fixed.

The invention described in claim 3 is the first or second invention.
Wherein the rotor has a thin portion between a contact portion with the stator and the rotating shaft, and the vibration damping member is fixed to the thin portion.

According to a fourth aspect of the present invention, in the ultrasonic motor according to any one of the first to third aspects, the vibration damping member is fitted and fixed at a position corresponding to the traveling wave vibration. .

According to a fifth aspect of the present invention, in the ultrasonic motor according to the fourth aspect, the fixed portions of the vibration damping member are equally spaced in the circumferential direction by a number different from a divisor of the wave number of the traveling wave vibration. And

According to a sixth aspect of the present invention, in the ultrasonic motor according to the fourth aspect, the vibration damping member is provided with the same number of fixed portions as divisors of the wave number of the traveling wave vibration, and each of the fixed portions has a circumferential direction. The pitch was unequal.

According to a seventh aspect of the present invention, in the ultrasonic motor according to any one of the fourth to sixth aspects, the vibration damping members are individually provided at positions corresponding to the wave number of the traveling wave vibration. Can be

According to an eighth aspect of the present invention, in the ultrasonic motor according to the seventh aspect, the vibration damping members are formed in the same shape. According to a ninth aspect of the present invention, in the ultrasonic motor according to any one of the fourth to sixth aspects, the vibration damping member includes a single member.

According to a tenth aspect of the present invention, a rotor is pressed against a stator having a piezoelectric element, and traveling wave vibration is generated based on the driving of the piezoelectric element. In the ultrasonic motor to be rotated, the rotor has an annular recess on the side opposite to the stator and is connected to the rotating shaft so as to be movable in the axial direction and integrally rotatable. A pressure plate connected to the rotating shaft so as not to be separated by a predetermined distance or more, and an urging member that is assembled between the plate and the rotor in a compressed and deformed state and generates the press contact force by the urging force. A vibration damping member is fitted over a predetermined circumferential position or the entire circumference of the annular concave portion of the rotor, and a pressure is applied by the pressing plate or the urging member. Is, the vibration damping member is incapable fixedly fitted escape.

According to an eleventh aspect of the present invention, in the ultrasonic motor according to the tenth aspect, the rotor has an annular thin portion between a contact portion with the stator and the rotating shaft. The annular concave portion is formed to constitute the thin portion.

(Operation) According to the first aspect of the present invention,
Since the vibration damping member for reducing unnecessary vibration is configured to be fitted and fixed in a through hole provided at a predetermined location in the circumferential direction of the rotor, the vibration damping member is easily and reliably fixed to the rotor. be able to.

According to the second aspect of the present invention, the vibration damping member has a projection to be inserted into the through hole of the rotor, and the projection is heated by heating the tip of the projection after the projection is inserted into the through hole. It is deformed and fixed. With this configuration, the vibration damping member can be easily and reliably fixed to the rotor.

According to the third aspect of the present invention, the vibration damping member is fixed to the thin portion provided between the contact portion of the rotor with the stator and the rotating shaft. Since the thin portion attenuates unnecessary vibration from its own shape, the unnecessary vibration can be further attenuated by the vibration damping member.

According to the fourth aspect of the present invention, the vibration damping member is fitted and fixed to the rotor at a position corresponding to traveling wave vibration generated in the stator. Therefore, among the unnecessary vibrations generated by the rotor during the rotation of the rotor, the vibration component that adversely affects the traveling wave vibration can be efficiently attenuated.

According to the fifth aspect of the present invention, the fixed portions of the vibration damping member are equally spaced in the circumferential direction by a number different from a divisor of the number of traveling wave vibrations. In addition, the vibration component having the same wave number as the traveling wave vibration which adversely affects the traveling wave vibration can be reliably attenuated without transmitting.

According to the sixth aspect of the present invention, the fixed portion of the vibration damping member has the same number as the divisor of the wave number of the traveling wave vibration and has an irregular pitch in the circumferential direction. Of these, the vibration component having the same wave number as the traveling wave vibration which adversely affects the traveling wave vibration can be reliably attenuated without transmitting.

According to the seventh aspect of the present invention, the vibration damping members are individually provided at positions corresponding to the wave number of the traveling wave vibration. Can be attenuated.

According to the eighth aspect of the present invention, since the vibration damping members are formed in the same shape, the vibration damping members can be easily formed, and the members can be easily managed.

According to the ninth aspect of the present invention, since the vibration damping member is constituted by one member, the vibration component which adversely affects the traveling wave vibration can be reliably attenuated with a small number of parts.

According to the tenth aspect of the present invention, a vibration damping member for reducing unnecessary vibration is fitted over a predetermined circumferential position or the entire circumference of the annular concave portion provided on the rotor, and the rotor is positioned opposite to the stator. The vibration damping member can be easily and securely fixed to the rotor because the compression damping member is configured to be fitted and fixed so that it cannot be pulled out by the pressing plate or the urging member provided on the side.

According to the eleventh aspect of the present invention, the annular concave portion is formed so as to constitute a thin portion provided between the contact portion of the rotor with the stator and the rotating shaft.
No special recess for fitting the vibration damping member is required. Therefore, there is no need to perform extra processing on the rotor.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 1, a housing 2 of the ultrasonic motor 1 includes a base 3 and a cover 4, and a rotating shaft 5 inserted through the housing 2
And are rotatably supported by bearings 6 and 7 fixed to the cover 4. A disk-shaped stator 8 is fixed to the upper surface of the base 3 with screws 9. A vibrating portion 8 a is formed on the outer periphery of the stator 8, and a piezoelectric element 11 is fixed to the lower surface of the vibrating portion 8 a via a base ring 10. When a predetermined high-frequency driving voltage is applied to the piezoelectric element 11, the piezoelectric element 11 vibrates, and the piezoelectric element 11
Is a traveling wave vibration in the vibration part 8a of the stator 8. In this embodiment, the wave number of the traveling wave vibration is “9”.
It is set to be.

Above the stator 8, the disk-shaped rotor 1
2 are provided. The rotor 12 includes a resin collar 13 and a stator contact member 14. Resin color 1
3 is a connecting portion 5 provided on the rotating shaft 5 and having a substantially square cross section.
The stator contact member 14 is connected to the resin collar 13 so as to be integrally rotatable with respect to a. That is, the rotor 12
The rotary shaft 5 is connected to the connecting portion 5a so as to be movable in the axial direction and to be integrally rotatable.

As shown in FIGS. 1 and 2, the stator contact member 14 of the rotor 12
3, a thin portion 14b formed outside the base portion 14a, and an outer peripheral portion 14c formed outside the thin portion 14b.

The thin portion 14b has a thin plate thickness in the axial direction and is formed in an annular shape. In the thin portion 14b, eight circular through holes 14d are provided on the same circumference at equal intervals in the circumferential direction. A disc-shaped anti-vibration rubber 15 having the same shape is fixed to each through hole 14d. Specifically, a substantially cylindrical projection 15a is provided on the bottom surface of the vibration-isolating rubber 15, and this projection 15a is formed in the through hole 14d of the thin portion 14b.
The tip of the projection 15a is deformed by heat staking so that it cannot come out of the through hole 14d,
Is fixed so as not to fall off the thin portion 14b. Since the vibration-proof rubber 15 is provided for each through hole 14d, eight vibration-proof rubbers are provided at regular intervals in the circumferential direction. As described above, in the present embodiment, since the anti-vibration rubber 15 is configured to be fitted and fixed so as not to come out, the mounting of the anti-vibration rubber 15 to the rotor 12 becomes easy and reliable.

The outer peripheral portion 14c is provided with a lining material 16 on its lower surface. The lower surface of the lining material 16 is a sliding contact surface 16a as a contact portion, and the sliding contact surface 16a
Is in sliding contact with the vibrating portion 8a of the stator 8.

A disc spring 17 is disposed on the upper surface of the rotor 12 (resin collar 13), and a pressure plate 18 is disposed on the upper surface of the disc spring 17. And the disc spring 1
Reference numeral 7 denotes a state where the plate 18 is compressed and deformed by the plate 18 and the rotor 12, and the plate 18 is non-rotatably connected to the rotary shaft 5 (the connecting portion 5a) and is further immovably connected by the circlip 19. Therefore, the disc spring 17 presses the upper surface of the rotor 12 by its restoring force, and the rotor 1
2 is pressed against the stator 8.

In the ultrasonic motor 1 thus configured, when the piezoelectric element 11 is driven, the vibrating section 8 of the stator 8
A traveling wave vibration is generated at a, and the rotor 12 and the rotating shaft 5 rotate based on the traveling wave vibration, and the rotational force is transmitted to the load.

When the driving force fluctuates suddenly, for example, when the ultrasonic motor 1 is started or stopped, shock vibration (unnecessary vibration) occurs between the load and the rotating shaft 5 or between the rotating shaft 5 and the rotor 12. ) Is generated, and the vibration propagates from the rotation shaft 5 side of the rotor 12 to the outer peripheral side.
Is attenuated.

Here, among the unnecessary vibrations, the traveling wave vibration generated in the vibrating portion 8a of the stator 8 has a great influence because the vibration having nine wavelengths in the circumferential direction which is the same as the wave number "9" of the traveling wave vibration. Component. Therefore, in the present embodiment, by providing a different number (eight) of vibration isolating rubbers 15 at equal intervals in the circumferential direction different from the divisor of the wave number “9”,
The configuration is such that vibration components having nine wavelengths in the circumferential direction that adversely affect traveling wave vibration are reliably attenuated without transmitting. In this way, the vibration isolating rubber 15 is connected to the vibrating portion 8a of the stator 8
By setting the number and the arrangement position in accordance with the traveling wave vibration generated in the rotor, the rotor 1 can be used without using an extra material.
Unnecessary vibrations propagating from the second motor 2 to the stator 8 are efficiently reduced, so that uneven rotation of the ultrasonic motor 1, reduction in output, and generation of abnormal noise (noise) are reduced.

As described above, according to the present embodiment,
It has the following effects. (1) The anti-vibration rubber 15 has a projection 15a to be inserted into the through hole 14d of the rotor 12, and the projection 15a is connected to the through hole 14d.
After being inserted into the projection, the tip of the projection 15a is deformed so that it cannot be pulled out by heat staking. Therefore, the anti-vibration rubber 15 can be fixed to the rotor 12 easily and in a short time as compared with the conventional adhesive fixing.

(2) The anti-vibration rubber 15 is fixed to the thin portion 14b provided on the rotor 12. Since the thin portion 14b attenuates unnecessary vibrations from its own shape, the unnecessary vibrations can be more efficiently attenuated by the vibration-proof rubber 15.

(3) The rotor 12 is provided with a number of anti-vibration rubbers 15 different from the divisor of the wave number "9" of the traveling wave vibration generated in the stator 8 at equal intervals in the circumferential direction. That is,
The rotor 12 is provided with anti-vibration rubbers 15 in a number and an arrangement position corresponding to the traveling wave vibration generated in the stator 8. Here, since the ultrasonic motor disclosed in the above publication has a configuration in which the elastic member is simply provided over the entire circumference of the rotor, it cannot be said that unnecessary vibration is suppressed efficiently. That is, the ultrasonic motor disclosed in the above publication excessively uses an elastic member, which not only increases the cost, but also increases the weight of the rotor to increase the inertial force and decrease the responsiveness. I will. In the present embodiment, the anti-vibration rubber 15 is provided at the number and the position corresponding to the traveling wave vibration generated in the stator 8, so that the unnecessary vibration generated in the rotor 12 when the rotor 12 rotates is adversely affected by the traveling wave vibration. The transmission of the nine-wavelength vibration component in the circumferential direction that gives Therefore, the vibration component having the same wave number as the traveling wave vibration which adversely affects the traveling wave vibration can be efficiently and reliably attenuated with a small material. As a result, the material cost of the vibration isolating rubber 15 can be reduced. In addition, since the weight of the rotor 12 can be reduced and the inertial force can be reduced, the responsiveness can be improved.

(4) Since the anti-vibration rubbers 15 are formed in the same shape, the anti-vibration rubbers 15 can be easily formed, and the management of the rubbers 15 is easy. (5) Since the rubber isolators 15 are provided at equal intervals in the circumferential direction of the rotor 12, the balance during rotation of the rotor 12 is not deteriorated. Also, a through hole 1 for attaching the vibration isolating rubber 15 is provided.
4d may be provided at equal intervals in the circumferential direction.
Is easy to design and manufacture.

The embodiment of the present invention may be modified as follows. In the above embodiment, the number of vibration-proof rubbers 15 different from the divisor of the wave number “9” of the traveling-wave vibration generated in the stator 8 in the rotor 12 is provided at equal intervals in the circumferential direction. Fifteen
The number and arrangement position of are not limited to this. Also, anti-vibration rubber 15
Is the same as the divisor of the wave number of the traveling wave vibration, for example, as in the rotor 12a shown in FIG.
5 may be provided. In this case, the nine anti-vibration rubbers 15
In the circumferential direction, the distances L1 to L9 need to be arranged at different unequal pitches. Even with the anti-vibration rubber 15 provided in this manner, the rotor 12
Of the unnecessary vibrations generated in the above, the vibration component having the same wave number as the traveling wave vibration which adversely affects the traveling wave vibration can be reliably attenuated without transmitting.

In the above embodiment, the vibration isolating rubber 15 is
However, the present invention is not limited to this shape. Further, although the shape of the vibration-proof rubber 15 is the same, the shape may be different from each other.

Further, as shown in FIG. 4, an anti-vibration rubber 20 formed in an annular shape may be used. In addition, this anti-vibration rubber 20
Is provided with eight projections 20a corresponding to the through holes 14d, and similarly to the above-described embodiment, the tip of the projection 20a is deformed so as not to come out of the through hole 14d by heat staking and does not fall out of the thin portion 14b. Is fixed.
Even in this case, the vibration component having the same wave number as the traveling wave vibration that has a bad influence on the traveling wave vibration can be reliably attenuated. In addition, since only one vibration-proof rubber 20 is required, the number of parts can be reduced. Needless to say, an annular anti-vibration rubber 20 may be used in the embodiment shown in FIG. In this case, the projection 20
It is necessary to change the position a in accordance with the position of the through hole 14d.

In the above-described embodiment, the vibration-isolating rubber 15 is fixed by heat staking, but may be fixed by any other method. For example, the projection 15a may be formed in advance in a shape that cannot be pulled out of the through hole 14d.

Further, as in the case of the ultrasonic motor 1a shown in FIG. 5, the vibration-proof rubber 15a may be fitted and fixed.
More specifically, as shown in FIG. 6, a stator 8 and a rotating shaft 5 are mounted on a base 3, and a stator 12
After the b is placed, the vibration isolating rubber 21 having the same annular shape and rectangular cross section is fitted into the annular concave portion 14e formed on the upper surface of the rotor 12b (the stator contact member 14) so as to form the thin portion 14b. . The axial size of the vibration-proof rubber 21 is set to be slightly larger than the distance between the upper surface of the thin portion 14b (the bottom surface of the concave portion 14e) and the lower surface of the disc spring 17 when assembled. The disc spring 17 and the pressure plate 18 are placed with the vibration isolating rubber 21 fitted in the fitting recess 14e, and the circlip 19 is attached with the disc spring 17 compressed and deformed. . At this time, the anti-vibration rubber 21 is compressed on the lower surface of the disc spring 17, and the anti-vibration rubber 21 does not rattle. Therefore, also in this embodiment, the anti-vibration rubber 21 can be fixed easily and reliably. Further, since the annular concave portion 14e formed to form the thin portion 14b is used, a special concave portion for fitting the vibration-proof rubber 21 is not required. That is, there is no need to perform extra processing on the rotor 12b (the stator contact member 14). The diameter of the disc spring 17 may be reduced, and the vibration isolating rubber 21 may be compressed on the lower surface of the pressure plate 18.

In the above embodiment, the vibration damping rubber 15 made of a rubber material is used as the vibration damping member. However, if the vibration damping member is used, the vibration damping member may be formed of a material other than the rubber material, for example, a synthetic resin material. You may.

In the above embodiment, the vibration-proof rubber 15 is provided on the thin portion 14b, but may be provided on other portions of the rotor 12. In the above embodiment, the ultrasonic motor 1 is configured as shown in FIG. 1, but the configuration is not limited to this.

The technical ideas other than the claims that can be grasped from the above embodiments are described below. (A) In a rotor of an ultrasonic motor that rotates a rotating shaft by being rotated by traveling wave vibration generated in a stator, a through hole is provided at a predetermined position in a circumferential direction, and a vibration damping member is fitted and fixed to the through hole so that it cannot come out. A rotor for an ultrasonic motor.

(B) In the ultrasonic motor rotor according to (a), the vibration damping member is fitted and fixed at a position corresponding to the wave number of the traveling wave vibration. Rotor.

[0050]

As described in detail above, according to the present invention,
It is possible to provide an ultrasonic motor that can easily and reliably fix a vibration damping member for reducing unnecessary vibration.

[Brief description of the drawings]

FIG. 1 is a sectional view of an ultrasonic motor according to an embodiment.

FIG. 2A is a perspective view of a rotor, and FIG. 2B is a plan view of the rotor.

FIG. 3A is a perspective view of another example of a rotor,
(B) is a top view of another example of a rotor.

FIG. 4A is a perspective view of another example of a rotor,
(B) is an exploded perspective view of another example of a rotor.

FIG. 5 is a sectional view of an ultrasonic motor according to another example.

FIG. 6 is an exploded view of an ultrasonic motor according to another example.

[Explanation of symbols]

5: rotating shaft, 8: stator, 11: piezoelectric element, 12, 1
2a, 12b: rotor, 14b: thin portion, 14d: through hole, 14e: annular concave portion, 15, 20, 21: anti-vibration rubber as a vibration damping member, 15a, 20a: projection, 16a ...
A sliding contact surface as a contact portion, 17 a coned disc spring as a biasing member, 18 a pressure plate.

Continued on the front page F term (reference) 5H680 AA00 AA06 AA18 BB03 BB16 CC02 CC07 DD01 DD02 DD03 DD15 DD23 DD53 DD66 DD75 DD85 DD92 EE03 FF03 FF04 FF06 GG11 GG19

Claims (11)

[Claims] An ultrasonic motor in which a rotor is pressed against a stator having a piezoelectric element, traveling wave vibration is generated based on driving of the piezoelectric element, and the traveling wave vibration rotates the rotor to rotate a rotating shaft. An ultrasonic motor, wherein a through hole is provided at a predetermined position in a circumferential direction of the rotor, and a vibration damping member is fitted and fixed to the through hole so as not to come out. 2. The ultrasonic motor according to claim 1, wherein the vibration damping member has a projection fitted into the through hole.
An ultrasonic motor, wherein the projection is fitted into the through-hole, and the tip of the projection is heated so as to be deformed so as not to come out and fixed. 3. The ultrasonic motor according to claim 1, wherein the rotor has a thin portion between a contact portion with the stator and the rotating shaft, and the thin portion has the vibration portion. An ultrasonic motor having a damping member fixed thereto. 4. The ultrasonic motor according to claim 1, wherein the vibration damping member is fitted and fixed at a position corresponding to the wave number of the traveling wave vibration. Ultrasonic motor. 5. The ultrasonic motor according to claim 4, wherein the fixed portions of the vibration damping member are circumferentially equally spaced by a number different from a divisor of the wave number of the traveling wave vibration. Ultrasonic motor. 6. The ultrasonic motor according to claim 4, wherein the fixed portion of the vibration damping member has a non-uniform pitch in the circumferential direction in the same number as a divisor of the wave number of the traveling wave vibration. Ultrasonic motor. 7. The ultrasonic motor according to claim 4, wherein the vibration damping members are individually provided at positions corresponding to the wave number of the traveling wave vibration. Sound wave motor. 8. The ultrasonic motor according to claim 7, wherein the vibration damping members are formed in the same shape. 9. The ultrasonic motor according to claim 4, wherein said vibration damping member is formed of a single member. 10. An ultrasonic motor in which a rotor is pressed against a stator having a piezoelectric element, traveling wave vibration is generated based on driving of the piezoelectric element, and the rotor is rotated by the traveling wave vibration to rotate a rotating shaft. The rotor has an annular recess on the side opposite to the stator and is connected to the rotating shaft so as to be axially movable and integrally rotatable. On the side opposite to the stator of the rotor, the rotor is not separated from the rotor by a predetermined distance or more. A pressure plate connected to the rotating shaft, and an urging member that is assembled between the plate and the rotor in a compressed and deformed state and generates the pressing force by an urging force thereof; A vibration damping member is fitted over a predetermined circumferential position or the entire circumference of the annular concave portion of the rotor, and is compressed by the pressing plate or the urging member. Ultrasonic motor, characterized in that it is coming off incapable fixedly fitted. 11. The ultrasonic motor according to claim 10, wherein the rotor has an annular thin portion between a contact portion with the stator and the rotating shaft, and the annular recess is An ultrasonic motor characterized by being formed to form a thin portion.