Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02N—ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
  • H02N2/00—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction
  • H02N2/10—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction producing rotary motion, e.g. rotary motors
  • H02N2/16—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction producing rotary motion, e.g. rotary motors using travelling waves, i.e. Rayleigh surface waves
  • H02N2/166—Motors with disc stator
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02N—ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
  • H02N2/00—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction
  • H02N2/10—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction producing rotary motion, e.g. rotary motors
  • H02N2/12—Constructional details
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02N—ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
  • H02N2/00—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction
  • H02N2/10—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction producing rotary motion, e.g. rotary motors
  • H02N2/16—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction producing rotary motion, e.g. rotary motors using travelling waves, i.e. Rayleigh surface waves
  • H02N2/163—Motors with ring stator

Definitions

• the present invention relates to a rotor, a stator, and an ultrasonic motor.
• Patent Document 1 discloses one example of an ultrasonic motor.
• the rotor is rotated by progressive vibration waves generated in the stator.
• the stator in Patent Document 1 consists of a ring-shaped piezoelectric body bonded to a ring-shaped elastic body. Vibration of the piezoelectric body generates a progressive vibration wave in the elastic body.
• the rotor consists of a ring-shaped slider material bonded to a ring-shaped rotor base material. The slider material of the rotor is in contact with the elastic body of the stator. When the rotor rotates, the slider material slides on the surface of the elastic body.
• the slider material in Patent Document 1 is made of resin.
• the rotor When an ultrasonic motor with a resin slider material is used in a high-humidity environment, the rotor may stick to the stator, causing the stator and rotor to become fixed together, preventing the ultrasonic motor from starting. This phenomenon is called "sticking.”
• the slider material When a slider material made of resin slides over the surface of the stator, the slider material generates wear particles that are broken down into small pieces due to mechanical friction, and low-molecular-weight components that are decomposed by frictional heat.
• the inventors discovered that the low-molecular-weight components generated by the slider material include water-soluble components.
• the inventors discovered that when a water-soluble component, or a mixture of a water-soluble component and wear particles, is exposed to moisture and then dries, it functions as an adhesive, allowing the stator and rotor to be fixed to each other. This can lead to sticking.
• the rotor according to the present invention is used in an ultrasonic motor equipped with a stator having a vibrating body and a vibration generating element mounted on the vibrating body. It comprises a rotor body and a sliding material mounted on the rotor body and in contact with the vibrating body, the sliding material being made of carbon graphite.
• the stator according to the present invention is a stator used in an ultrasonic motor equipped with a rotor, and comprises a vibrating body, a vibration generating element provided on the vibrating body, and a sliding material provided on the vibrating body and in contact with the rotor, the sliding material being made of carbon graphite.
• the ultrasonic motor according to the present invention comprises a rotor configured according to the present invention, the vibrating body, and the stator having the vibration generating element provided on the vibrating body.
• the motor is provided with a stator configured according to the present invention and the rotor.
• the rotor, stator, and ultrasonic motor according to the present invention can suppress adhesion.
• FIG. 1 is a schematic front cross-sectional view of an ultrasonic motor according to a first embodiment of the present invention.
• FIG. 2 is a schematic plan view of a stator according to the first embodiment of the present invention.
• FIG. 3 is a schematic plan view of a rotor according to the first embodiment of the present invention.
• FIG. 4 is a schematic cross-sectional view taken along line II in FIG.
• FIG. 5 is a schematic front cross-sectional view of a piezoelectric element according to a first embodiment of the present invention.
• FIG. 6 is a schematic plan view of a rotor according to a second embodiment of the present invention.
• FIG. 7 is a schematic plan view of a rotor according to a third embodiment of the present invention.
• FIG. 1 is a schematic front cross-sectional view of an ultrasonic motor according to a first embodiment of the present invention.
• FIG. 2 is a schematic plan view of a stator according to the first embodiment of the present invention.
• FIG. 8 is a schematic plan view of a rotor according to a modified example of the third embodiment of the present invention.
• FIG. 9 is a schematic cross-sectional view showing a portion of a rotor according to a fourth embodiment of the present invention, which corresponds to the cross section taken along line II in FIG.
• FIG. 10 is a schematic cross-sectional view showing a state in which the portion of the rotor according to the fourth embodiment of the present invention shown in FIG. 9 is in contact with the vibrating body of the stator, and a traveling wave is generated in the stator.
• FIG. 11 is a schematic cross-sectional view showing a portion of a rotor according to a modified example of the fourth embodiment of the present invention, corresponding to the cross section taken along line II in FIG. FIG.
• FIG. 12 is a schematic bottom view of a stator according to a fifth embodiment of the present invention.
• FIG. 13 is a schematic bottom view of a stator according to a sixth embodiment of the present invention.
• FIG. 14 is a schematic cross-sectional view taken along line II-II in FIG.
• FIG. 1 is a schematic front cross-sectional view of an ultrasonic motor according to a first embodiment of the present invention.
• the ultrasonic motor 1 has a stator 2, a rotor 4, and a shaft member 10.
• the stator 2 and rotor 4 are in contact.
• the rotor 4 is a rotor according to one embodiment of the present invention.
• the rotor 4 rotates due to traveling waves generated in the stator 2.
• the shaft member 10 rotates in conjunction with the rotation of the rotor 4.
• the central axis of rotation of the ultrasonic motor 1 is located at the portion where the shaft member 10 is provided. The specific configuration of the ultrasonic motor 1 is described below.
• Figure 2 is a schematic plan view of the stator in the first embodiment.
• the stator 2 has a plate-shaped vibrating body 3.
• the vibrating body 3 has a disk-like shape.
• the vibrating body 3 has a first main surface 3a and a second main surface 3b.
• the first main surface 3a and the second main surface 3b face each other.
• a through-hole 3c is provided in the center of the vibrating body 3. As shown in Figure 1, a shaft member 10 is inserted into the through-hole 3c. Note that the position of the through-hole 3c is not limited to the center of the vibrating body 3. The through-hole 3c may be located in an area that includes the central axis of rotation. Furthermore, the shape of the vibrating body 3 is not limited to a disk shape.
• the axial direction Z refers to the direction connecting the first principal surface 3a and the second principal surface 3b, and is the direction along the central axis of rotation. In this embodiment, the axial direction Z is parallel to the direction in which the shaft member 10 extends.
• the shape of the vibrating body 3 when viewed from the axial direction Z may be a regular polygon such as a regular hexagon, regular octagon, or regular decagon. In this specification, polygons are also defined as shapes in which the parts corresponding to the vertices are curved or chamfered.
• a view from the axial direction Z may be referred to as a planar view.
• the vibrating body 3 is made of an appropriate metal. However, the vibrating body 3 does not necessarily have to be made of metal.
• the vibrating body 3 may be made of other elastic materials, such as ceramics or silicon material.
• a plurality of piezoelectric elements 13 are provided on the first main surface 3a of the vibrating body 3.
• the piezoelectric elements 13 are vibration generating elements in the present invention.
• the plurality of piezoelectric elements 13 are distributed in the circumferential direction. More specifically, the plurality of piezoelectric elements 13 are distributed along the circumferential direction of a traveling wave so as to generate a traveling wave that circulates around an axis parallel to the axial direction Z.
• a structure in the stator 2 in which a plurality of piezoelectric elements 13 are distributed in the circumferential direction and driven to generate a traveling wave is disclosed, for example, in International Publication No. 2010/061508. Therefore, a detailed description of the generation of a traveling wave will be omitted.
• Figure 3 is a schematic plan view of the rotor in the first embodiment.
• the rotor 4 has a rotor body 4A and a sliding member 7.
• the rotor body 4A has a circular ring shape in a plan view.
• a through hole 4c is provided in the center of the rotor body 4A.
• the shaft member 10 shown in Figure 1 is inserted into the through hole 4c.
• the position of the through hole 4c is not limited to the center of the rotor body 4A.
• the through hole 4c only needs to be located in an area that includes the central axis of rotation.
• the shape of the rotor body 4A is not limited to the above.
• the outer shape of the rotor body 4A in a plan view may be a regular polygon such as a regular hexagon, regular octagon, or regular decagon.
• the sliding material 7 is provided on the rotor body 4A.
• the sliding material 7 has a circular ring shape in a plan view.
• the sliding material 7 is provided so as to surround the through-hole 4c of the rotor body 4A.
• the sliding material 7 is a member that comes into contact with the stator 2 shown in FIG. 1. In this embodiment, specifically, it comes into contact with the vibrating body 3 of the stator 2.
• the sliding material 7 of the rotor 4 slides on the surface of the vibrating body 3 of the stator 2.
• the sliding material 7 is made of carbon graphite.
• the degree of graphitization R of the carbon graphite is the value obtained by dividing the peak value D by the peak value G.
• the lubricity of the sliding material 7 may be reduced.
• the wear resistance of the sliding material 7 may be reduced.
• carbon powder is solidified by compression molding to obtain a carbon solid.
• the carbon solid is then heat-treated to promote partial crystallization of the carbon solid.
• a portion of the carbon solid is converted from carbon to graphite.
• carbon graphite is obtained by promoting partial crystallization of carbon solid, and is a type of amorphous carbon.
• the rotor body 4A has a rotor base portion 5 and a leaf spring portion 6.
• the outer shape of the rotor body 4A in a plan view is the outer shape of the rotor base portion 5 in a plan view.
• the through hole 4c of the rotor body 4A is provided in the rotor base portion 5.
• the leaf spring portion 6 has a circular ring shape in a plan view.
• the leaf spring portion 6 is provided so as to surround the through hole 4c.
• the rotor base portion 5 can be made of a suitable metal or suitable ceramic.
• the leaf spring portion 6 can be made of a suitable metal.
• Figure 4 is a schematic cross-sectional view taken along line I-I in Figure 3.
• the dashed lines in Figure 4 schematically indicate the displacement of the leaf spring portion, which will be described later.
• the rotor base portion 5 has a recess 5a. Although not shown, the recess 5a has a circular ring shape in plan view.
• a leaf spring portion 6 is provided on the rotor base portion 5 to cover the recess 5a.
• the leaf spring portion 6 has a first surface 6a and a second surface 6b. The first surface 6a and the second surface 6b face each other. Of the first surface 6a and the second surface 6b, the first surface 6a is located on the stator 2 side shown in FIG. 1.
• the sliding material 7 is provided on the leaf spring portion 6 of the rotor body 4A.
• this includes cases where the other member is provided directly on the other member, and cases where the other member is provided indirectly on the other member via another layer or the like.
• the sliding material 7 is provided directly on the leaf spring portion 6.
• the sliding material 7 may also be joined to the leaf spring portion 6 with a joining member such as an adhesive.
• the width of the sliding material 7 is narrower than the width of the leaf spring portion 6 and the width of the recessed portion 5a. In this embodiment, the width of the sliding material 7 is the distance between the inner and outer peripheral edges of the sliding material 7 in a planar view. The same applies to the width of the leaf spring portion 6 and the width of the recessed portion 5a.
• a feature of this embodiment is that a sliding material 7 is provided on the rotor body 4A of the rotor 4, and the sliding material 7 is made of carbon graphite. This makes it possible to prevent adhesion even when the ultrasonic motor 1 using the rotor 4 is used in a high humidity environment.
• Adhesion refers to the phenomenon in which the rotor sticks to the stator, the stator and rotor are fixed together, and the ultrasonic motor cannot be started. The above effect is explained in detail below.
• the rotor base portion 5 has a recess 5a, and that a leaf spring portion 6 is provided on the rotor base portion 5 so as to cover the recess 5a. It is also preferable that a sliding member 7 is provided on the leaf spring portion 6. This allows the rotor 4 to rotate efficiently. This is explained below.
• the vibration of the piezoelectric element 13, which serves as a vibration generating element displaces the vibrating body 3, generating a traveling wave.
• the vibrating body 3 has some areas that undergo large displacement and some areas that undergo small displacement. More specifically, when a traveling wave is generated, the displacement is greatest at the crest of the traveling wave in the vibrating body 3. The displacement is also large in the areas of the vibrating body 3 surrounding the crest.
• a sliding material 7 is provided on the leaf spring portion 6. Therefore, the leaf spring portion 6 elastically deforms as shown by the dashed line in Figure 4 in response to the displacement of the vibrating body 3 due to the traveling wave. This allows the wave crest portion of the vibrating body 3 and its surrounding area to come into contact with the sliding material 7 when a traveling wave is generated. This makes it possible to increase the area of contact between the largely displaced portion of the vibrating body 3 and the sliding material 7 on the rotor 4. This therefore increases the frictional force between the vibrating body 3 and the rotor 4, allowing the rotor 4 to rotate efficiently.
• the configuration in which the rotor base portion 5 has a recess 5a and the leaf spring portion 6 is provided on the rotor base portion 5 to cover the recess 5a can also be applied to configurations of the present invention other than this embodiment.
• the rotor main body 4A does not necessarily have to have the leaf spring portion 6.
• the rotor base portion 5 does not necessarily have to have the recess 5a.
• the sliding member 7 only needs to be provided on the rotor main body 4A so as to contact the stator 2.
• the ultrasonic motor 1 has a first case member 8 and a second case member 9.
• the second case member 9 is cap-shaped, and the first case member 8 is lid-shaped.
• the first case member 8 and the second case member 9 form a case.
• a spring member 16, a rotor 4, and a stator 2 are arranged inside the case.
• the first case member 8 has a first cylindrical protrusion 8a and a second cylindrical protrusion 8b.
• the first cylindrical protrusion 8a protrudes to the outside of the case.
• the second cylindrical protrusion 8b protrudes to the inside of the case.
• a portion of the second cylindrical protrusion 8b is located within the through-hole 3c of the vibrating body 3 of the stator 2.
• a through-hole 8c is provided continuously between the first cylindrical protrusion 8a and the second cylindrical protrusion 8b.
• a first bearing portion 18 is provided in the through-hole 8c at the location of the first cylindrical protrusion 8a.
• the shaft member 10 is inserted through the through-hole 8c and the first bearing portion 18. The shaft member 10 protrudes from the through-hole 8c of the first case member 8 to the outside of the case. Note that the configuration of the first case member 8 is not limited to the above.
• the second case member 9 has a cylindrical protrusion 9a.
• the cylindrical protrusion 9a protrudes to the outside of the case.
• a through hole 9c is provided in the cylindrical protrusion 9a.
• a second bearing portion 19 is provided in the through hole 9c.
• the shaft member 10 is inserted into the through hole 9c and the second bearing portion 19.
• the shaft member 10 protrudes to the outside of the case from the through hole 9c of the second case member 9.
• the configuration of the second case member 9 is not limited to the above.
• a plain bearing or a bearing may be used for the first bearing portion 18 and the second bearing portion 19.
• the sliding material 7 of the rotor 4 contacts the second main surface 3b of the vibrating body 3 in the stator 2.
• the second main surface 3b includes a contact surface 3d.
• the contact surface 3d is the portion of the second main surface 3b that contacts the rotor 4.
• the contact surface 3d is flat. More specifically, the contact surface 3d does not have an uneven structure.
• the contact surface 3d is configured in the same way as the portion of the second main surface 3b other than the contact surface 3d. Therefore, when obtaining the stator 2 of this embodiment, there is no need to cut the second main surface 3b of the vibrating body 3. This increases the productivity of the ultrasonic motor 1.
• An elastic member 12 is provided on the rotor base portion 5 of the rotor 4. More specifically, the elastic member 12 sandwiches the rotor 4 together with the stator 2 in the axial direction Z.
• the elastic member 12 has an annular shape. Note that the shape of the elastic member 12 is not limited to the above. Materials that can be used for the elastic member 12 include, for example, rubber or resin. However, the elastic member 12 does not necessarily have to be provided.
• a spring member 16 is disposed on the second bearing portion 19 side of the elastic member 12. More specifically, in this embodiment, the spring member 16 is a metal leaf spring. A through hole 16c is provided in the center of the spring member 16. The shaft member 10 is inserted through the through hole 16c. The shaft member 10 has a wide portion 10a. The width of the wide portion 10a of the shaft member 10 is wider than the width of other portions of the shaft member 10. Note that the width of the shaft member 10 is the dimension along a direction perpendicular to the axial direction Z of the shaft member 10. The inner peripheral edge of the spring member 16 abuts against the wide portion 10a. This prevents misalignment between the spring member 16 and the shaft member 10. However, the material and configuration of the spring member 16 are not limited to those described above. The configuration of the shaft member 10 is also not limited to those described above.
• a retaining ring 17 is provided on the shaft member 10.
• the retaining ring 17 has an annular shape. In a plan view, the retaining ring 17 surrounds the shaft member 10. More specifically, the inner peripheral edge of the retaining ring 17 is located within the shaft member 10. The retaining ring 17 abuts against the first bearing portion 18 from the outside in the axial direction Z. This defines the length between the retaining ring 17 and the wide portion 10a of the shaft member 10, and determines the amount of deflection of the spring member 16. This allows the spring member 16 to apply an elastic force to the rotor 4, as described above.
• the shaft member 10 and the retaining ring 17 can be made of materials such as metal or resin.
• the stator 2 has multiple piezoelectric elements 13.
• the specific configuration of the piezoelectric elements 13 is shown below.
• Figure 5 is a schematic front cross-sectional view of a piezoelectric element according to the first embodiment.
• the piezoelectric element 13 has a piezoelectric body 14.
• the piezoelectric body 14 has a third main surface 14a and a fourth main surface 14b.
• the third main surface 14a and the fourth main surface 14b face each other.
• the piezoelectric element 13 has a first electrode 15A and a second electrode 15B.
• the first electrode 15A is provided on the third main surface 14a of the piezoelectric body 14, and the second electrode 15B is provided on the fourth main surface 14b.
• the shape of the piezoelectric element 13 in a plan view is rectangular. However, the shape of the piezoelectric element 13 in a plan view is not limited to the above and may be, for example, elliptical.
• the stator 2 has four piezoelectric elements 13. Note that the number of piezoelectric elements 13 is not limited to the above. It is sufficient that multiple piezoelectric elements 13 are distributed along the direction of rotation of the traveling wave so as to generate a traveling wave that rotates around an axis parallel to the axial direction Z.
• the stator 2 may have a single piezoelectric element divided into multiple regions.
• each region of the piezoelectric element may be polarized in a different direction.
• the shape of the piezoelectric element in a plan view may be, for example, an annular shape.
• the first electrode 15A shown in Figure 5 is attached to the first main surface 3a of the vibrating body 3 with an adhesive.
• the thickness of this adhesive is very thin. Therefore, the first electrode 15A is electrically connected to the vibrating body 3.
• the rotor base portion 5 has a groove portion 5b that connects to the inner peripheral edge of the recessed portion 5a.
• the rotor base portion 5 has a groove portion 5c that connects to the outer peripheral edge of the recessed portion 5a.
• Groove portions 5b and 5c each have an annular shape in a plan view.
• a leaf spring portion 6 is provided from groove portion 5b to groove portion 5c. More specifically, the inner peripheral edge of leaf spring portion 6 is located within groove portion 5b. The outer peripheral edge of leaf spring portion 6 is located within groove portion 5c.
• the thickness of the leaf spring portion 6 when the thickness of the leaf spring portion 6 is set to the desired thickness, the thickness of the portion of the leaf spring portion 6 that protrudes from the rotor base portion 5 in the axial direction Z can be made thinner.
• the leaf spring portion 6 if the dimension corresponding to the depth of groove portions 5b and 5c is equal to or greater than the dimension corresponding to the thickness of the leaf spring portion 6, the leaf spring portion 6 can be configured not to protrude from the rotor base portion 5 in the axial direction Z. This makes it less likely that the leaf spring portion 6 will peel off from the rotor base portion 5.
• the rotor base 5, which has grooves 5b and 5c, and the leaf spring 6 are fitted together.
• grooves 5b and 5c do not necessarily have to be provided.
• the ultrasonic motor 1 of this embodiment shown in Figure 1 is just one example, and the configuration of the ultrasonic motor 1 is not limited to the above.
• the configuration of the stator 2 is not limited to the above.
• the stator 2 only needs to have an appropriate vibrating body 3 and a vibration generating element provided on the vibrating body 3.
• the sliding member 7 only needs to be provided so as to come into contact with the vibrating body 3 of the stator 2.
• Figure 6 is a schematic plan view of a rotor according to a second embodiment of the present invention.
• the annular orbit A is indicated by a dashed line.
• the rotor 24 of this embodiment differs from the rotor 4 of the first embodiment in that it has multiple sliding members 27.
• the multiple sliding members 27 are dispersed and arranged on an annular track A.
• the rotor 24 of this embodiment has the same configuration as the rotor 4 of the first embodiment.
• the annular orbit A is a circular orbit.
• the annular orbit A corresponds to an orbit along the circumferential direction of a traveling wave generated in a stator used together with the rotor 24 in an ultrasonic motor. Therefore, the multiple sliding members 27 are dispersed and arranged along the circumferential direction of the traveling wave.
• the multiple sliding members 27 are made of carbon graphite. As a result, in this embodiment, as in the first embodiment, adhesion can be suppressed.
• each sliding material 27 is arranged so that the center of gravity of each sliding material 27 is located on the annular orbit A. This allows the ultrasonic motor, when the rotor 24 is used in an ultrasonic motor, to be driven more reliably and stably. Note that it is sufficient that any part of the sliding material 27 is located on the annular orbit A. The center of gravity of the sliding material 27 does not necessarily have to be located on the annular orbit A.
• the width of the sliding material 27 is narrower than the width of the leaf spring portion 6 and the width of the recess 5a in the rotor base portion 5.
• the width of the sliding material 27 in this embodiment is the dimension of the sliding material 27 along a direction perpendicular to the annular track A in a plan view.
• Figure 7 is a schematic plan view of a rotor according to the third embodiment.
• the protruding portions of the sliding members, which will be described later, are indicated by hatching.
• the rotor 34 of this embodiment differs from the rotor 4 of the first embodiment in that the sliding member 37 has multiple protrusions 37a. Other than the above, the rotor 34 of this embodiment has the same configuration as the rotor 4 of the first embodiment.
• the sliding material 37 has a circular ring shape in plan view.
• the multiple protrusions 37a of the sliding material 37 are distributed and arranged along a circular track.
• the multiple protrusions 37a are distributed and arranged along the circumferential direction of a traveling wave generated in a stator used together with the rotor 34 in an ultrasonic motor.
• the multiple protrusions 37a protrude outward in the axial direction Z from the rotor main body 4A side. Therefore, the multiple protrusions 37a protrude toward the vibrating body side of the stator.
• the multiple protrusions 37a of the sliding material 37 come into contact with the vibrating body.
• the sliding material 37 multiple protruding portions 37a are connected to each other by portions other than the protruding portions 37a. More specifically, the sliding material 37 has multiple protruding portions 37a and multiple non-protruding portions 37b. The thickness of the non-protruding portions 37b is thinner than the thickness of the protruding portions 37a. Adjacent protruding portions 37a are connected to each other by the non-protruding portions 37b.
• the sliding material 37 is configured so that, in the circumferential direction of the traveling wave generated in the stator used together with the rotor 34, portions that come into contact with the vibrating body of the stator and portions that are thinner than these portions are alternately provided. This configuration reduces the rigidity of the rotor 34 in the circumferential direction of the traveling wave.
• the leaf spring portion 6 can be made to more effectively follow the displacement of the vibrating body of the stator. This allows the wave crest and its surrounding area of the vibrating body to come into more reliable contact with the sliding material 37 when a traveling wave is generated. This increases the contact area between the largely displaced part of the vibrating body and the sliding material 37 of the rotor 34. This increases the frictional force between the vibrating body and the rotor 34, allowing the rotor 34 to rotate more reliably and efficiently.
• the sliding material 37 in this embodiment corresponds to a single member formed by connecting multiple sliding materials 27 in the second embodiment.
• the portions of the sliding material 37 that correspond to the multiple sliding materials 27 are multiple protrusions 37a. Because the sliding material 37 is a single member having the above-described configuration, the sliding material 37 is easy to handle, and the rotor 34 is easy to process and assemble. This increases the productivity of the rotor 34. Furthermore, the strength of the connection between the sliding material 37 and the leaf spring portion 6 in the rotor main body 4A can be increased.
• the thickness of the sliding member 37 other than the protruding portion 37a i.e., the thickness of the non-protruding portion 37b, is preferably 70% or less of the thickness of the protruding portion 37a, and more preferably 30% or less. This more reliably reduces the rigidity of the rotor 34 in the circumferential direction of the traveling wave.
• the sliding material 37 is made of carbon graphite. This makes it possible to suppress adhesion, just like in the first embodiment.
• the width of the protruding portion 37a and the width of the non-protruding portion 37b are the same. However, this is not limited to this.
• the width of the non-protruding portion 37b is wider than the width of the protruding portion 37a. Because the width of the non-protruding portion 37b is wider, the strength of the connection between the sliding material 37A and the leaf spring portion 6 of the rotor body 4A can be effectively increased.
• the sliding material 37A is made of carbon graphite. This makes it possible to suppress adhesion, just like in the third embodiment.
• the rotor 44 of this embodiment differs from the rotor 4 of the first embodiment in that the rotor body 44A consists only of a rotor base portion, and the rotor base portion does not have a recess. In other words, the rotor 44 does not have a leaf spring portion.
• the rotor 44 of this embodiment also differs from the rotor 4 of the first embodiment in that it has a soft resin layer 48.
• the rotor 44 of this embodiment differs from the rotor 4 of the first embodiment in that the width of the sliding material 7 is the same as the width of the rotor body 44A. Apart from the above, the rotor 44 of this embodiment has the same configuration as the rotor 4 of the first embodiment.
• the soft resin layer 48 refers to a resin layer having a relatively low Young's modulus or flexural modulus. Specifically, it is preferable that the Young's modulus of the soft resin layer 48 is 80% or less of the Young's modulus of the sliding material 7, or that the flexural modulus of the soft resin layer 48 is 80% or less of the flexural modulus of the sliding material 7.
• the soft resin layer 48 can be made of, for example, epoxy resin, phenolic resin, or polyphenylene sulfide (PPS) resin.
• the soft resin layer 48 may be a resin layer in which an additive is added to an appropriate resin to adjust the Young's modulus to 80% or less of that of the sliding material 7, or the flexural modulus to 80% or less of that of the sliding material 7.
• the soft resin layer 48 may be a resin layer in which an additive is added to an appropriate resin to adjust at least one of the Young's modulus and flexural modulus to 7 GPa or less.
• the soft resin layer 48 is provided between the rotor body 44A and the sliding material 7.
• the rotor 44 has a configuration in which the rotor body 44A, soft resin layer 48, and sliding material 7 are layered in this order.
• all portions of the sliding material 7 are provided on the soft resin layer 48.
• the sliding material 7 may include portions that are not provided on the soft resin layer 48.
• the rotor 44 is used in an ultrasonic motor together with a stator having a vibrating body.
• the portion where the sliding material 7 and soft resin layer 48 are laminated needs to overlap, in a plan view, with the wave crest portion and its surrounding portion of the vibrating body when a traveling wave is generated in the stator.
• the soft resin layer 48 and the sliding material 7 may be bonded together with a separate bonding material such as an adhesive.
• the soft resin layer 48 may be the bonding material that bonds the rotor body 44A and the sliding material 7 together.
• the width of the sliding material 7 and the width of the rotor body 44A are the same.
• the width of the sliding material 7 may be narrower than the width of the rotor body 44A.
• Figure 10 is a schematic cross-sectional view showing the state in which the portion of the rotor according to the fourth embodiment shown in Figure 9 is in contact with the vibrating body of the stator, and a traveling wave is generated in the stator.
• a portion of the rotor 44 elastically deforms in response to the displacement of the vibrating body 3 due to the traveling wave. More specifically, the soft resin layer 48 elastically deforms. Accordingly, as shown by the arrow in Figure 10, the sliding material 7 also deforms. This allows the wave crest portion of the vibrating body 3 and its surrounding area to come into contact with the sliding material 7 when a traveling wave is generated. This makes it possible to increase the area of contact between the largely displaced portion of the vibrating body 3 and the sliding material 7 of the rotor 44. This therefore increases the frictional force between the vibrating body 3 and the rotor 44, allowing the rotor 44 to rotate more reliably and efficiently.
• the soft resin layer 48 elastically deforms in response to the displacement of the vibrating body 3 in the stator, changing the resonant state of the stator. Specifically, part of the vibration energy in the stator is converted into heat as the soft resin layer 48 elastically deforms. In other words, the vibration energy in the stator is absorbed. As a result, the mechanical quality factor Qm of the resonant state of the stator decreases, and the amplitude of the vibrating body 3 in the stator decreases. Note that the greater the amplitude of the vibrating body 3, the higher the maximum rotation speed of the ultrasonic motor. On the other hand, the elastic deformation of the soft resin layer 48 has the effect of widening the range of frequencies in which the stator resonates. This effect is called the damping effect.
• the damping effect makes it easier for the stator to enter a resonant state, even when variations in the stator vibration occur. Therefore, even when variations in the stator vibration occur, the rotor 44 can be rotated appropriately, and the ultrasonic motor can be driven appropriately.
• the Young's modulus or flexural modulus of the soft resin layer 48 through selection of the material for the soft resin layer 48, it is possible to adjust the balance between the amplitude of vibration in the vibrating body 3 and the width of the frequency range in which the stator resonates.
• the above balance can also be adjusted by adjusting the thickness of the soft resin layer 48, etc.
• the sliding material 7 is made of carbon graphite. This makes it possible to suppress adhesion, just like in the first embodiment.
• the leaf spring portion 6 shown in FIG. 4 may be provided.
• the rotor base portion 5 of the rotor main body 4A has a recess 5a.
• the leaf spring portion 6 is provided on the rotor base portion 5 so as to cover the recess 5a.
• the soft resin layer 48 is provided between the leaf spring portion 6 and the sliding material 7.
• the sliding material 7 is indirectly provided on the leaf spring portion 6 via the soft resin layer 48.
• the leaf spring portion 6, soft resin layer 48, and sliding material 7 are layered in this order.
• All parts of the sliding material 7 overlap the recess 5a of the rotor base portion 5 in a plan view.
• the width of the sliding material 7 is narrower than the width of the leaf spring portion 6 and the width of the recess 5a.
• the rotor 54 is used in an ultrasonic motor together with a stator having a vibrating body.
• the leaf spring portion 6 and soft resin layer 48 elastically deform in response to the displacement of the vibrating body due to the traveling wave.
• the sliding material 7 also elastically deforms in response to the elastic deformation of the soft resin layer 48. This allows the wave crest and surrounding areas of the vibrating body to come into more reliable contact with the sliding material 7 when a traveling wave is generated. This therefore makes it possible to more reliably increase the contact area between the largely displaced part of the vibrating body and the sliding material 7 of the rotor 54. This therefore increases the frictional force between the vibrating body and the rotor 54, allowing the rotor 54 to rotate more reliably and efficiently.
• the rotor 54 can be rotated appropriately, and the ultrasonic motor can be driven appropriately.
• the Young's modulus or flexural modulus of the soft resin layer 48 through selection of the material for the soft resin layer 48, it is possible to adjust the balance between the amplitude of vibration in the stator vibrating body and the width of the frequency range in which the stator resonates.
• the above balance can also be adjusted by adjusting the thickness of the soft resin layer 48, etc.
• absorption of vibration energy in the stator also occurs as a result of the elastic deformation of the leaf spring portion 6, which follows the displacement of the vibrating body in the stator.
• the degree of elastic deformation of the leaf spring portion 6 can be adjusted by selecting the material of the leaf spring portion 6, adjusting the thickness of the leaf spring portion 6, or adjusting the width of the recess 5a in the rotor base portion 5. This makes it possible to adjust the amount of vibration energy absorbed in the stator as a result of the elastic deformation of the leaf spring portion 6.
• the sliding material 7 is also made of carbon graphite. This makes it possible to suppress adhesion, just like in the fourth embodiment.
• the rotor 54 may have a plurality of sliding members 27 in the second embodiment shown in FIG. 6 or sliding member 37 in the third embodiment shown in FIG. 7. In these cases, the rigidity of the rotor 54 in the circumferential direction of the traveling wave generated in the stator used together with the rotor 54 can be reduced. As a result, as in the second and third embodiments, the frictional force between the stator's vibrating body and the rotor 54 can be increased, allowing the rotor 54 to rotate more reliably and efficiently.
• the rotor 44 of the fourth embodiment may have, instead of the sliding member 7, the multiple sliding members 27 of the second embodiment shown in FIG. 6 or the sliding member 37 of the third embodiment shown in FIG. 7.
• the rigidity of the rotor 44 in the circumferential direction of the traveling wave generated in the stator used together with the rotor 44 can be reduced.
• the frictional force between the stator vibrator and the rotor 44 can be increased, allowing the rotor 44 to rotate more reliably and efficiently.
• FIG. 12 is a schematic bottom view of a stator according to a fifth embodiment of the present invention.
• the stator 62 of this embodiment differs from the stator 2 of the first embodiment in that it includes a sliding member 7. Other than the above, the stator 62 of this embodiment has the same configuration as the stator 2 of the first embodiment.
• a sliding material 7 is provided on the second main surface 3b of the vibrating body 3 in the stator 62.
• the sliding material 7 has a configuration similar to that of the sliding material 7 of the rotor 4 in the first embodiment. Specifically, the sliding material 7 in this embodiment has a circular ring shape in a plan view.
• the sliding material 7 is made of carbon graphite.
• the sliding material 7 is arranged to surround the through-hole 3c of the vibrator 3 in the stator 62.
• the stator 62 is used together with a rotor in an ultrasonic motor.
• the sliding material 7 in the stator 62 is a member that comes into contact with the rotor. When the ultrasonic motor is driven, the surface of the rotor slides over the sliding material 7. Therefore, when the ultrasonic motor is driven, the sliding material 7 in the stator 62 slides over the surface of the rotor, relatively.
• the stator 62 may have, for example, a plurality of sliding members 27 in the second embodiment shown in FIG. 6 or the sliding member 37 in the third embodiment shown in FIG. 7.
• the stator 62 may have, for example, the sliding member 37A in the modified example of the third embodiment shown in FIG. 8.
• FIG. 13 is a schematic bottom view of a stator according to the sixth embodiment.
• FIG. 14 is a schematic cross-sectional view taken along line II-II in FIG. 13. Piezoelectric elements are omitted from FIGS. 13 and 14.
• this embodiment differs from the fifth embodiment in that multiple protrusions 73e are provided on the second main surface 73b of the vibrating body 73.
• This embodiment also differs from the fifth embodiment in that multiple sliding members 27 are provided.
• the stator 72 of this embodiment has the same configuration as the stator 62 of the fifth embodiment. Therefore, the vibrating body 73 has a first main surface 73a and a second main surface 73b, and a through hole 73c is provided in the vibrating body 73.
• the piezoelectric elements are omitted from Figures 13 and 14. However, in this embodiment, as in the fifth embodiment, multiple piezoelectric elements are provided on the first main surface 73a of the vibrating body 73.
• a plurality of protrusions 73e are provided on the second main surface 73b of the vibrating body 73, surrounding the through-hole 73c.
• the plurality of protrusions 73e are dispersed and arranged on an annular orbit.
• the annular orbit is a circular orbit.
• the plurality of protrusions 73e are dispersed and arranged along the circumferential direction of the traveling wave generated in the stator 72.
• the multiple protrusions 73e protrude outward in the axial direction Z from the second main surface 73b of the vibrating body 73.
• the multiple protrusions 73e protrude toward the rotor.
• One sliding member 27 is provided on each of the multiple protrusions 73e. Therefore, like the multiple protrusions 73e, the multiple sliding members 27 are dispersed along the circumferential direction of the traveling wave generated in the stator 72. The multiple sliding members 27 come into contact with the rotor.
• the multiple sliding members 27 are made of carbon graphite. As a result, in this embodiment, as in the fifth embodiment, adhesion can be suppressed.
• multiple protrusions 73e protrude outward in the axial direction Z from the second main surface 73b.
• the tips of the multiple protrusions 73e are displaced even more greatly.
• the rotor then comes into contact with the sliding members 27 provided on the surfaces of the tips of the protrusions 73e on the second main surface 73b. Therefore, the rotor can be rotated efficiently by the traveling wave generated in the stator 72.
• the displacement of the traveling wave generated in the stator 72 is specifically a displacement caused by the flexural deformation of the vibrating body 73.
• This displacement caused by the flexural deformation is a displacement parallel to the axial direction Z. Therefore, when a traveling wave is generated, flexural deformation occurs on the first main surface 73a and second main surface 73b of the vibrating body 73. As described above, the tips of the multiple protrusions 73e provided on the second main surface 73b are displaced even more significantly.
• each sliding material 27 made of carbon graphite due to excessive flexural deformation.
• flexural deformation is less likely to occur in each sliding material 27. Therefore, cracks in each sliding material 27 can be more reliably suppressed.
• the ultrasonic motor according to the present invention may, for example, include the rotor according to the present invention and an appropriate stator.
• the ultrasonic motor according to the present invention may include an appropriate rotor and the stator according to the present invention. This can help prevent sticking.
• ⁇ 3> A rotor according to ⁇ 1> or ⁇ 2>, wherein the rotor body has a rotor base portion having a recess and a leaf spring portion provided on the rotor base portion so as to cover the recess, and the sliding material is provided on the leaf spring portion.
• ⁇ 4> The rotor described in ⁇ 3>, further comprising a soft resin layer provided between the leaf spring portion and the sliding material.
• ⁇ 5> The rotor described in ⁇ 1> or ⁇ 2>, further comprising a soft resin layer disposed between the rotor body and the sliding material.
• ⁇ 7> A rotor described in any one of ⁇ 1> to ⁇ 5>, wherein the sliding member includes, in a plan view, a plurality of protrusions dispersedly arranged on a circular track, and the plurality of protrusions protrude toward the vibrating body.
• a stator used in an ultrasonic motor equipped with a rotor comprising a vibrating body, a vibration generating element provided on the vibrating body, and a sliding material provided on the vibrating body and in contact with the rotor, the sliding material being made of carbon graphite.
• An ultrasonic motor comprising the rotor described in any one of ⁇ 1> to ⁇ 7>, the vibrating body, and the stator having the vibration generating element provided on the vibrating body.
• An ultrasonic motor comprising the stator described in ⁇ 8> or ⁇ 9> and the rotor.

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• 2024
  • 2024-10-04 JP JP2025512819A patent/JPWO2025197156A1/ja active Pending
  • 2024-10-04 CN CN202480045782.2A patent/CN121464575A/zh active Pending
  • 2024-10-04 WO PCT/JP2024/035647 patent/WO2025197156A1/ja active Pending
• 2025
  • 2025-11-19 US US19/394,037 patent/US20260081542A1/en active Pending

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