JP2009033791A - Ultrasonic motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic motor with good repeatability (reproducibility of drive speed) and speed stability. <P>SOLUTION: The ultrasonic motor includes an ultrasonic vibrator 2, a plurality of drive elements 2b bonded to the ultrasonic vibrator 2, a plurality of first relative motion members 5A abutting against the plurality of drive elements 2b, respectively, a plurality of second relative motion members 5B facing the plurality of first relative motion members 5A, and boss members 5C provided in contact with the plurality of first relative motion members 5A and the plurality of second relative motion members 5B wherein the plurality of boss members 5C have such a profile as making the inclination of the first relative motion member 5A follow up the inclination of the friction member 2b and are provided at positions corresponding to the plurality of drive elements 2b, respectively, and the first and second members 5A and 5B are bonded through the boss member 5C under a state where the inclination of the first relative motion member 5A is following up the inclination of the drive element 2b. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ultrasonic motor.

  In recent years, ultrasonic motors using vibrations of vibrators such as piezoelectric elements have attracted attention as new motors that replace electromagnetic motors. Compared with conventional electromagnetic motors, this ultrasonic motor provides low speed and high thrust without gears, high holding force, long stroke, high resolution, quietness, magnetic There is an advantage that no static noise is generated and the magnetic noise is not affected.

  In the above-described ultrasonic motor, in order to exert thrust and holding force, it is necessary to press the vibrator against the driven body, and it is also necessary not to transmit the vibration of the vibrator to the outside. For this reason, various mechanisms for pressing the vibrator in the ultrasonic motor against the driven body have been proposed.

  For example, Patent Document 1 discloses an elastic body formed in a rectangular parallelepiped shape, an electromechanical transducer that is attached to one plane of the elastic body and generates a plurality of types of vibrations in the elastic body, and the elastic body. A vibrator having a drive extraction portion formed on the other plane, a relative motion member that is pressed against the elastic body via the drive force extraction portion, and a drive force extraction portion are attached to the driving force extraction portion. A vibration actuator is disclosed in which the friction member is partially disposed with respect to the short side direction of the other plane of the elastic body.

  According to the vibration actuator disclosed in Patent Document 1, since the amplitude of the elliptical motion generated at the driving force extraction portion is in a substantially constant range at the mounting position of the friction member, the amplitude of the driving force extraction portion. Only the range where is substantially constant contacts the relative motion member, and the surface pressure of the contact portion is substantially constant.

As a result, according to the vibration actuator disclosed in Patent Document 1, slipping between the driving force extraction portion and the relative motion member is eliminated or reduced, and no sliding noise is generated due to driving, thereby reducing noise. The vibration transmission efficiency is improved and the driving efficiency is improved.
JP-A-9-331686

  By the way, in the conventional ultrasonic motor, due to component accuracy, assembly accuracy, stacking accuracy, and the like, the inclination of a driven member (for example, a sliding plate) that is a relative motion member, and a friction member (for example, a driving element). Does not match the slope of.

  Therefore, an angular deviation always occurs between the contact surfaces with respect to the contact angle between the sliding plate and the plurality of driving elements contacting the sliding plate.

  The following problems arise due to the poor contact state between the sliding plate and the drive element (unbalance of the contact area between the drive element and the sliding plate). . That is, regarding the driving speed of the sliding plate, the driving speed in one direction and the driving speed in the other direction are not the same. That is, the repeatability (reproducibility of driving speed) and speed stability of the ultrasonic motor are deteriorated.

  Note that the technology disclosed in Patent Document 1 does not disclose such problems and means for solving such problems at all.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an ultrasonic motor with good repeatability (reproducibility of driving speed) and good speed stability.

  In order to achieve the above object, the ultrasonic motor according to the first aspect of the present invention generates an elliptical vibration by simultaneously generating a longitudinal vibration and a bending vibration in a piezoelectric element, and a driving force is generated by the elliptical vibration. In the obtained ultrasonic motor for driving the driven member, an ultrasonic vibrator having a piezoelectric element, a plurality of friction members fixed to the ultrasonic vibrator and in contact with the driven member, and the plurality of friction members A plurality of first members each abutting against the friction member, a second member facing the plurality of first members, and between each of the plurality of first members and the second member. A plurality of contact members provided in contact with each other, and a driven member driven by a frictional force between the plurality of friction members, wherein the plurality of contact members are the first contact members. It is a shape that makes the inclination of the member follow the inclination of the friction member. And the first member and the second member are provided in positions corresponding to each of the plurality of friction members, in a state where the inclination of the first member follows the inclination of the friction member, It is characterized by being bonded and fixed via a contact member.

  In order to achieve the above object, the ultrasonic motor according to the second aspect of the present invention generates an elliptical vibration by simultaneously generating a longitudinal vibration and a bending vibration in the piezoelectric element, and a driving force is generated by the elliptical vibration. In the obtained ultrasonic motor for driving the driven member, an ultrasonic vibrator having a piezoelectric element, a plurality of friction members fixed to the ultrasonic vibrator and in contact with the driven member, and the plurality of friction members A plurality of first members each in contact with the friction member, a facing surface facing the plurality of first members, and a recessed portion at a position corresponding to each of the plurality of friction members on the facing surface. A driven member that has a second member and a plurality of contact members that are accommodated in the respective recesses and that are in contact with the first members facing each other, and that is driven by a friction force between the plurality of friction members. And the plurality of The contact member has a shape that causes the inclination of the first member to follow the inclination of the friction member, and the first member and the second member have an inclination of the first member that follows the inclination of the friction member. In the state, it is bonded and fixed via the contact member.

  According to the present invention, it is possible to provide an ultrasonic motor with good repeatability (reproducibility of driving speed) and good speed stability.

  Hereinafter, an ultrasonic motor according to an embodiment of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a perspective view showing the configuration of the ultrasonic motor according to the first embodiment of the present invention. FIG. 2A is a front view showing the configuration of the ultrasonic motor according to the first embodiment of the present invention. FIG. 2B is a top view showing the configuration of the ultrasonic motor according to the first embodiment of the present invention. FIG. 2C is a cross-sectional view taken along line AA illustrated in FIG. FIG. 2D is a cross-sectional view taken along the line AA shown in FIG. 2A when a driver element 2b described later is greatly inclined.

  The ultrasonic motor 1 according to the first embodiment includes an ultrasonic vibrator 2, a driven member 5 that is brought into contact with the ultrasonic vibrator 2 and is driven relative to the ultrasonic vibrator 2, A rolling member 6 disposed between the driven member 5 and a fixing member 7 described later, a fixing member 7 which is a casing of the ultrasonic motor 1 and to which the ultrasonic transducer is fixed, and an ultrasonic wave And a pressing member 8 for pressing the vibrator 2 against the driven member 5.

  The ultrasonic transducer 2 includes, for example, a rectangular parallelepiped piezoelectric element 2a formed by laminating a plurality of sheet-shaped internal electrodes provided on one side of a rectangular plate-shaped piezoelectric ceramic sheet, and one of the piezoelectric elements 2a. And two frictional contacts (hereinafter referred to as drive elements) 2b that are bonded to the side surfaces and are brought into close contact with the driven member 5.

  The piezoelectric element 2a excites the longitudinal vibration shown in FIG. 3 and the secondary bending vibration shown in FIG. 4 by applying an alternating voltage of a predetermined pattern to the internal electrode. Particularly, as shown in FIG. 4, the secondary bending vibration includes nodes A1, A2, and A3 of standing waves of vibration at three positions with an interval in the longitudinal direction of the piezoelectric element 2a. Then, an antinode B1 of the vibration standing wave is formed between the nodes A1 and A2, and an antinode B2 of the vibration standing wave is formed between the nodes A2 and A3.

  Here, the driver 2b is formed in a rectangular parallelepiped block shape, and is fixed with an adhesive or the like at a position corresponding to the antinodes B1 and B2 of the secondary bending vibration in the piezoelectric element 2a.

  The driven member 5, which is one of the main features of the ultrasonic motor according to the first embodiment, includes a first relative motion member 5 </ b> A that is in close contact with the driver 2 b and the rolling member 6. A second relative motion member 5B placed on the first relative motion member 5C, and a projection member 5C provided on the first relative motion member 5A.

  The protruding member 5C is formed in a hemispherical shape, and is provided on the first relative motion member 5A so that the spherical convex portion is in contact with the second relative motion member 5B. That is, the protruding member 5C is in point contact with the second relative motion member 5B at the spherical convex portion so as not to hinder the movement of the first relative motion member 5A.

  Here, the protrusion members 5C are provided on the first relative motion member 5A at the same number as the driver elements 2b and at positions corresponding to the driver elements 2b, that is, one-to-one corresponding to the driver elements 2b. Yes.

  The rolling member 6 is formed in a spherical shape, and is provided on the fixing member 7. As described above, the second relative motion member 5 </ b> B is installed on the rolling member 6. Here, the arrangement position of the driven member 5 in the moving direction (directions indicated by arrows A and B in FIG. 2A) is regulated by, for example, a retainer (not shown).

  By the way, in order to take the structure mentioned above, the ultrasonic motor which concerns on this 1st Embodiment is assembled | attached as follows, for example. First, the rolling member 6 is placed on the fixed member 7, and the driven member 5 having the above-described configuration is placed on the rolling member 6.

  Subsequently, the ultrasonic transducer 2 is placed on the driven member 5 so that the first relative motion member 5A and the driver 2b come into contact with each other. Further, the ultrasonic transducer 2 is pressed and fixed to the fixing member 7 side by the pressing member 8 which is a pressing spring screwed to the fixing member 7 by a screw member 9 (FIG. 2B). reference).

  Thereafter, the first relative motion member 5A and the second relative motion member 5B are bonded and fixed by, for example, an adhesive or the like by the following process.

  That is, when assembled as described above, each first relative motion member 5A and the first relative motion member 5A are moved by the movement of the contact point between the protrusion member 5C and the second relative motion member 5B. It tilts following the tilt of the surface of the contacting driver 2b.

  Accordingly, the inclination of the surface of each first relative motion member 5A in contact with each driver 2b and the inclination of the contact surface of each driver 2b with each first relative motion member 5A coincide (FIG. 2). (See (D)). At this time, the contact angles between the respective driver elements 2b and the corresponding first relative motion members 5A are all equal.

  In this state, the first relative motion member 5A and the second relative motion member 5B are bonded and fixed by the adhesive 11 as shown in FIG. That is, the first relative motion member 5A and the second relative motion member 5B are integrated via the protruding member 5C.

  With the configuration as described above, when the driven member 5 is driven, the driving speed in the direction indicated by the arrow A in FIG. 2A and the driving speed in the direction indicated by the arrow B are set to the same driving speed. The driven member 5 can be driven relative to the ultrasonic transducer 2 and the fixing member 7.

  As described above, according to the first embodiment, it is possible to provide an ultrasonic motor with good repeatability (drive speed reproducibility) and speed stability.

  More specifically, in the ultrasonic motor according to the first embodiment, the driven member 5 includes three members, that is, a first relative motion member 5A, a second relative motion member 5B, and a protruding member 5C. The projecting member 5C is brought into contact with the first relative motion member 5A and the second motion member 5B so as to ensure a high degree of freedom of the movable range of the first relative motion member 5A. The inclination of the first relative motion member 5A can be made equal to the inclination of the driver 2b.

  Accordingly, the inclination of the surface of the first relative motion member 5A that contacts the driver 2b is made to coincide with the inclination of the surface of the driver 2b that contacts the first relative motion member 5A, and each driver The contact angles between 2b and the corresponding first relative motion members 5A can be all equal.

  That is, according to the ultrasonic motor according to the first embodiment, the contact areas between the respective driver elements 2b and the corresponding first relative motion members 5A can be made equal to each other. .

  In such a state, since the first relative motion member 5A and the second relative motion member 5B are bonded and fixed together, the first relative motion member 5A and the second relative motion member 5B The driving speed of the driven member 5 comprising the protruding member 5C is the same when driven in the direction indicated by the arrow A in FIG. 2A and when driven in the direction indicated by the arrow B. Become. That is, the speed stability of the ultrasonic motor 1 is improved. Of course, repeatability (reproducibility of driving speed) is also improved.

  Of course, the number of the driver elements 2b is not limited to two. When three or more driver elements 2b are provided, the same number of the protruding members 5C correspond to each driver element 2b. It is provided on the first relative motion member 5A at the position to be moved.

  Needless to say, the shape of the protruding member 5C is not limited to a hemispherical shape. For example, the shape of the conical shape or the triangular pyramid shape, that is, the contact with the second relative motion member 5B is a point contact or the first shape. Any shape may be used as long as the surface contact does not impair the freedom of movement of the relative motion member 5A. In other words, the shape of the protruding member 5C may not be a shape that reduces the degree of freedom of movement of the first relative motion member 5A.

[First Modification]
Next, a modification of the ultrasonic motor according to the first embodiment will be described. In addition, the description which overlaps with the ultrasonic motor which concerns on 1st Embodiment mentioned above is abbreviate | omitted, and it demonstrates focusing on the difference between the ultrasonic motor which concerns on this modification, and the ultrasonic motor which concerns on the said 1st Embodiment. To do.

  FIG. 5A is a front view showing a configuration of an ultrasonic motor according to this modification. FIG. 5B is a cross-sectional view taken along line AA shown in FIG. 5A and 5B, the pressing member 8 is simply shown as a pressing member made of a pressing spring. The fixing member 7 is also shown in a simplified manner.

  In the ultrasonic motor according to the first embodiment, the protruding member 5C is provided on the first relative motion member 5A. On the other hand, in the ultrasonic motor according to this modification, as shown in FIGS. 5A and 5B, the protruding member 5C is provided on the second relative motion member 5B.

  That is, the protruding member 5C is formed in a hemispherical shape, and is provided on the second relative motion member 5B so that the spherical convex portion makes point contact with the first relative motion member 5A.

  The protrusion members 5C are provided on the second relative motion member 5B so as to correspond to the same number and positions corresponding to the driver elements 2b, that is, one-to-one with the driver elements 2b.

  Further, the shape of the protruding member 5C is a shape other than a hemispherical shape as long as it is a shape such as a conical shape or a triangular pyramid shape, that is, a shape in which the contact with the first relative motion member 5A is a point contact. Is of course good.

  In other words, the shape of the protruding member 5C is not, for example, a shape that makes surface contact with the first relative motion member 5A, that is, a shape that reduces the degree of freedom of movement of the first relative motion member 5A. Good.

  As described above, according to this modification, it is possible to provide an ultrasonic motor that has the same effects as the ultrasonic motor according to the first embodiment.

[Second Embodiment]
Next, an ultrasonic motor according to a second embodiment of the present invention will be described. In addition, the description which overlaps with the ultrasonic motor which concerns on the 1st modification mentioned above is abbreviate | omitted, and focuses on the difference between the ultrasonic motor which concerns on this 2nd Embodiment, and the ultrasonic motor which concerns on the said 1st modification. I will explain.

  FIG. 6A is a front view showing a configuration of an ultrasonic motor according to the second embodiment of the present invention. FIG. 6B is a cross-sectional view taken along line AA shown in FIG. In FIGS. 6A and 6B, the pressing member 8 is shown in a simplified manner as a pressing member composed of a pressing spring. The fixing member 7 is also shown in a simplified manner.

  That is, in the second embodiment, a recess 5D that engages with the protruding member 5C is provided in the first relative motion member 5A. The concave portion 5D is a hemispherical concave portion having a radius larger than the spherical convex radius of the protruding member 5C having a hemispherical shape, and engages with the protruding member 5C.

  Thus, by providing the concave portion 5D in the first relative motion member 5A, the assembly of the ultrasonic motor 1 becomes easier.

  As described above, according to the second embodiment, it is possible to provide an ultrasonic motor that has the same effects as those of the ultrasonic motor according to the first modified example and further improves the ease of assembly. .

[Second Modification]
Next, a modification of the ultrasonic motor according to the second embodiment will be described. In addition, the description which overlaps with the ultrasonic motor which concerns on 2nd Embodiment mentioned above is abbreviate | omitted, and it focuses on the difference between the ultrasonic motor which concerns on this modification, and the ultrasonic motor which concerns on the said 2nd Embodiment. To do.

  FIG. 7A is a front view showing a configuration of an ultrasonic motor according to the second modification. FIG. 7B is a cross-sectional view taken along line AA shown in FIG. 7A and 7B, the pressing member 8 is simply shown as a pressing member made of a pressing spring. The fixing member 7 is also shown in a simplified manner.

  In the ultrasonic motor according to the second embodiment, the protruding member 5C is provided in the second relative motion member 5B, and the recess 5D is provided in the first relative motion member 5A. On the other hand, in the ultrasonic motor according to this modification, as shown in FIGS. 7A and 7B, the protruding member 5C is provided on the first relative motion member 5A, and the concave portion 5D is disposed on the second relative motion. Provided on the member 5B.

  As described above, according to the second modification, it is possible to provide an ultrasonic motor that has the same effect as the ultrasonic motor according to the second embodiment.

[Third embodiment]
Next, an ultrasonic motor according to a third embodiment of the invention will be described. In addition, the description which overlaps with the ultrasonic motor which concerns on the 1st modification mentioned above is abbreviate | omitted, and focuses on the difference between the ultrasonic motor which concerns on this 3rd Embodiment, and the ultrasonic motor which concerns on the said 1st modification. I will explain.

  FIG. 8A is a front view showing a configuration of an ultrasonic motor according to this modification. FIG. 8B is a cross-sectional view taken along line AA illustrated in FIG.

  In the ultrasonic motor according to the first modification, the protruding member 5C is provided on the second relative motion member 5B. On the other hand, in the ultrasonic motor according to the third embodiment, the second relative motion member 5B is provided with a recess 5E instead of the protruding member 5C, and the spherical member 5F is accommodated in the recess 5E. As shown in FIGS. 8A and 8B, the spherical member 5F makes point contact with the first relative motion member 5A so as not to hinder the movement of the first relative motion member 5A.

  In this way, the spherical shape member 5F is brought into point contact with the first relative motion member 5A to ensure a high degree of freedom in the movable range, whereby the inclination of the first relative motion member 5A is increased. The inclination of the driver 2b is made to follow. In other words, the function of the protruding member 5C is assigned to the concave portion 5E and the spherical member 5F.

  The spherical member 5F is made of a vibration isolating material such as silicon rubber.

  As described above, according to the third embodiment, it is possible to provide an ultrasonic motor with high vibration isolation while exhibiting the same effects as the ultrasonic motor according to the first modification.

  More specifically, according to the ultrasonic motor according to the third embodiment, the sound generated by the ultrasonic motor 1 during driving can be reduced by the vibration-proofing effect of the spherical member 5F.

  Of course, the recess 5E may be provided not in the second relative motion member 5B but in the first relative motion member 5A.

  The present invention has been described based on the first to third embodiments. However, the present invention is not limited to the above-described embodiments, and various modifications and applications can be made within the scope of the gist of the present invention. Of course, it is possible.

  Further, the above-described embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and the effect described in the column of the effect of the invention Can be extracted as an invention.

The perspective view which shows the structure of the ultrasonic motor which concerns on 1st Embodiment of this invention. (A) is a front view showing the configuration of the ultrasonic motor according to the first embodiment of the present invention, (B) is a top view showing the configuration of the ultrasonic motor according to the first embodiment of the present invention, (C) is Sectional drawing in the AA shown to (A). (D) is sectional drawing in the AA shown to (A) at the time of the state in which the driver element inclined largely. The figure which shows the longitudinal vibration excited by a piezoelectric element by applying the alternating voltage of a predetermined pattern to an internal electrode. The figure which shows the bending vibration excited by a piezoelectric element by applying the alternating voltage of a predetermined pattern to an internal electrode. (A) is a front view which shows the structure of the ultrasonic motor which concerns on a 1st modification, (B) is sectional drawing in the AA line shown to (A). (A) is a front view which shows the structure of the ultrasonic motor which concerns on 2nd Embodiment, (B) is sectional drawing in the AA line shown to (A). (A) is a front view which shows the structure of the ultrasonic motor which concerns on a 2nd modification, (B) is sectional drawing in the AA line shown to (A). (A) is a front view which shows the structure of the ultrasonic motor which concerns on 3rd Embodiment, (B) is sectional drawing in the AA line shown to (A).

Explanation of symbols

    DESCRIPTION OF SYMBOLS 1 ... Ultrasonic motor, 2 ... Ultrasonic vibrator, 2a ... Piezoelectric element, 2b ... Driver, 5 ... Driven member, 5A ... First relative motion member, 5B ... Second relative motion member, 5C ... Projection member, 5D ... concave portion, 5E ... concave portion, 5F ... spherical member, 6 ... rolling member, 7 ... fixing member, 8 ... pressing member, 9 ... screw member, 11 ... adhesive.

Claims (6)

In an ultrasonic motor that generates elliptical vibration by simultaneously generating longitudinal vibration and bending vibration in a piezoelectric element, and obtains a driving force by the elliptical vibration to drive a driven member.
An ultrasonic transducer having a piezoelectric element;
A plurality of friction members fixed to the ultrasonic transducer and in contact with the driven member;
Between the plurality of first members that are in contact with the plurality of friction members, the second member that faces the plurality of first members, and between the plurality of first members and the second member, respectively. A plurality of contact members provided in contact with them, and a driven member driven by a frictional force between the plurality of friction members;
Comprising
The plurality of contact members have a shape that causes the inclination of the first member to follow the inclination of the friction member, and are provided at positions corresponding to the plurality of friction members,
The ultrasonic motor, wherein the first member and the second member are bonded and fixed via the contact member in a state where the inclination of the first member follows the inclination of the friction member.   The ultrasonic motor according to claim 1, wherein the contact member is formed integrally with the first member.   The ultrasonic motor according to claim 1, wherein the contact member is formed integrally with the second member. The second member is provided with a recess that engages with the contact member,
The ultrasonic motor according to claim 2, wherein the contact member provided on the first member is engaged with a concave portion provided on the second member. The first member is provided with a recess that engages with the contact member,
The ultrasonic motor according to claim 3, wherein the contact member provided on the second member is engaged with a recess provided on the first member. In an ultrasonic motor that generates elliptical vibration by simultaneously generating longitudinal vibration and bending vibration in a piezoelectric element, and obtains a driving force by the elliptical vibration to drive a driven member.
An ultrasonic transducer having a piezoelectric element;
A plurality of friction members fixed to the ultrasonic transducer and in contact with the driven member;
A plurality of first members that are in contact with the plurality of friction members; a plurality of first members that are opposed to each other; and a position corresponding to each of the plurality of friction members among the opposed surfaces. A second member having a recess; and a plurality of contact members that are accommodated in each of the recesses and are in contact with the first member facing each other, and are driven by a frictional force between the plurality of friction members. A driven member;
Comprising
The plurality of contact members are shaped to cause the inclination of the first member to follow the inclination of the friction member,
The ultrasonic motor, wherein the first member and the second member are bonded and fixed via the contact member in a state where the inclination of the first member follows the inclination of the friction member.

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