JP2015035909A - Vibration actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure an output performance when used as a motor while securing detection accuracy when used as a force sensor in a vibration actuator.SOLUTION: A vibration actuator 1 includes a rotor 30, a vibrator 10 which has a piezoelectric element 17 for generating ultrasonic vibration for rotating the rotor 30, a cover 60 which is provided around the vibrator 10, and two flanges 61 which protrude from the inner peripheral surface of the cover 60 to compressively support the vibrator 10. The flanges 61 fixedly support the vibrator 10 by holding it with elastic force by flexure when the vibration actuator 1 is used as a force sensor (at the time of non-rotation of the rotor 30), and support the vibrator 10 so as to be able to vibrate by vibrating sympathetically with the vibrator 10 when the vibration actuator 1 is used as an ultrasonic motor (at the time of rotation of the rotor 30).

Description

  The present invention relates to a vibration actuator provided with a piezoelectric element.

  The vibration actuator is provided with a rotor that is in pressure contact with the stator, and the stator is vibrated by applying an alternating voltage to a piezoelectric element provided in the stator, and the rotor is rotated by transmitting the vibration of the stator to the rotor. Let's get the driving force. A technique of using a piezoelectric element used for this vibration actuator as a force sensor for detecting a force applied to the vibration actuator is disclosed in, for example, Japanese Patent Application Laid-Open No. 2008-1000031 (Patent Document 1).

  Patent Document 1 discloses a robot hand having a finger portion driven by a vibration actuator. When this robotic hand uses a vibration actuator as a motor to move a finger part, the motor is driven using the reverse piezoelectric effect of the piezoelectric element (a phenomenon that deforms when a voltage is applied from the outside), so that an object, etc. Grip. On the other hand, when a piezoelectric element of a vibration actuator is used as a force sensor, a voltage is not applied to the piezoelectric element, but the piezoelectric effect of the piezoelectric element (a phenomenon that generates a voltage when deformed by an external force) is applied to the rotor. Detect the acting force.

JP 2008-1000031 A

  When a vibration actuator is used as a force sensor as in Patent Document 1, it is desirable to fix the stator so that it does not move due to the force acting on the rotor in order to increase the detection accuracy. However, if the stator is fixed constantly, vibrations of the stator during driving of the motor are hindered, resulting in a contradiction that the output performance (torque, rotational speed, efficiency, etc.) of the motor is reduced. Thus, ensuring the detection accuracy as the force sensor and securing the output performance as the motor are in a trade-off relationship with each other. Further improvement is necessary to achieve both of these trade-off relationships.

  The present invention has been made to solve the above-described problems, and its object is to ensure output performance when used as a motor while ensuring detection accuracy when used as a force sensor in a vibration actuator. That is.

  The vibration actuator according to the present invention includes a rotor, a vibrating body that is in contact with the rotor, and includes a piezoelectric element that generates ultrasonic vibration for rotating the rotor on a contact surface with the rotor. And a cover that is fixed to a member that rotatably supports the output shaft of the rotor, and a support member that is provided between the cover and the vibration member and supports the vibration member under pressure. The support member is configured to fixedly support the vibrating body with respect to the cover when the rotor is not rotating, and to support the vibrating body so as to be able to vibrate when the rotor is rotating.

  Preferably, the support member supports the vibrating body fixedly with respect to the cover by an elastic force when the rotor is not rotating, and supports the vibrating body so as to be able to vibrate by resonating with the vibrating body when the rotor rotates.

  Preferably, the support member is a beam-like member including a base end fixed to the cover, an arm portion extending along the outer peripheral surface of the vibrating body, and a distal end contacting the vibrating body. The beam-like member fixedly supports the vibrating body with respect to the cover by elastic force due to deflection when the rotor is not rotating, and resonates with the vibrating body when the rotor is rotating.

  Preferably, the support member supports a portion corresponding to an antinode of vibration during resonance of the vibrating body when the rotor is not rotating.

  Preferably, the support member is a rod-like member that is elastically stretchable in the longitudinal direction and has a base end rotatably supported inside the cover and a tip that is movable with respect to the vibrating body. When the rotor is not rotating, the rod-like member presses and contacts the predetermined part of the vibrating body to press the vibrating body fixedly to the cover, and when the rotor rotates, the tip that contacts the vibrating body from the predetermined part is supported. The vibrator is supported so as to vibrate by moving along the surface of the vibrator.

Preferably, the support member further includes a rod-shaped member elastic body that holds the rod-shaped member so that a tip of the rod-shaped member contacts a predetermined portion of the vibrating body when the rotor is not rotated.
The elastic body for a rod-shaped member allows the rod-shaped member to return to a predetermined portion when the rotor does not rotate while allowing the tip of the rod-shaped member to move along the surface of the vibrating body when the rotor rotates. To support.

Preferably, the predetermined portion is a portion corresponding to an antinode of vibration at the time of resonance of the vibrating body.
Preferably, the support member includes a plate-like member formed so as to be in contact with the outer peripheral surface of the vibrating body, and an elastic body for the plate-like member that presses the plate-like member against the vibrating body. The plate-like member supports the vibrating body fixedly to the cover by pressing and contacting the vibrating body by the elastic force of the elastic body for the plate-like member when the rotor does not rotate, and near-field acoustic waves when the rotor rotates. The vibrator is supported so as to vibrate by receiving a levitation force from the vibrator by a levitation action.

  Preferably, the support member includes a plurality of supports whose base ends are supported on the inside of the cover. The support member pressurizes and supports the vibrating body by sandwiching the vibrating body with a plurality of support bodies when the rotor is not rotating.

  Preferably, the vibrating body includes a stator that contacts the rotor, a base that is provided integrally with the stator and that is disposed so as to sandwich the piezoelectric element between the stator, and a preload portion that pressurizes and contacts the rotor with the stator. Further included. The support member supports the base of the vibrating body.

  According to the present invention, in a vibration actuator, it is possible to ensure output performance when used as a motor while securing detection accuracy when used as a force sensor.

It is a perspective view of a vibration actuator. It is a side perspective view of a vibration actuator. It is a side view of a vibration actuator. It is a figure which shows the IV-IV cross section of FIG. It is a figure which shows the frequency characteristic of a flange. It is a figure for demonstrating a plunger. It is a figure which shows the state change of a plunger. It is a figure for demonstrating a supporting member. It is a figure which shows the state change of a plate-shaped member.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  FIG. 1 is a perspective view of a vibration actuator 1 according to the present embodiment. FIG. 2 is a side perspective view of the vibration actuator 1 in the X direction of FIG. FIG. 3 is a side view of the vibration actuator 1 in the Y direction of FIG. 1 to 3, the axial center direction of the connecting rod 45 (see FIG. 2) is defined as the Z axis, the axis orthogonal to the Z axis is defined as the X axis, and is orthogonal to the Z axis and the X axis. The axis is defined as the Y axis.

  The vibration actuator 1 according to the present embodiment will be described with reference to FIGS. The vibration actuator 1 is configured to function as a so-called ultrasonic motor.

  The vibration actuator 1 is fixed to the bearing 30 and the rotor 30 having the rotating shaft 34, the vibrating body 10 that generates vibration for rotating the rotor 30, the bearing member 37 that rotatably supports the rotating shaft 34, and the bearing member 37. And the cover 60 formed. The cover 60 is a cylindrical casing that is provided around the vibrating body 10 and covers the vibrating body 10. In the present embodiment, the cover 60 is a cylindrical casing, but the present invention is not limited to this, and the cover 60 may be configured by a plurality of columns arranged at a predetermined interval.

  The vibrating body 10 includes a stator 13 that is in contact with the outer peripheral surface 31 of the rotor 30, a base portion 11 that is disposed farther from the rotor 30 than the stator 13, and a piezoelectric element 17 that is sandwiched between the stator 13 and the base portion 11. Is provided.

  A screw hole 12 is formed at the center of the base 11. The stator 13 includes a shaft portion 14 that can be screwed into the screw hole 12, and a columnar stator main body portion 15 formed on the proximal end side of the shaft portion 14. A male screw 16 corresponding to the screw hole 12 is formed near the tip of the shaft portion 14. The stator 13 has a through hole 22 that passes through the centers of the shaft portion 14 and the stator main body portion 15.

  A piezoelectric element 17 is provided between the base 11 and the stator main body 15. The piezoelectric element 17 has a substantially cylindrical shape and has a through hole 18 at the center. The shaft portion 14 of the stator 13 is inserted into the through hole 18 of the piezoelectric element 17 and is sandwiched between the base portion 11 and the piezoelectric element 17 is held by the vibrating body 10.

  The piezoelectric element 17 is electrically connected to a drive circuit (not shown). The piezoelectric element 17 generates ultrasonic vibration (elliptical motion) for rotating the rotor 30 on the contact surface 21 of the stator 13 with the rotor 30 when an AC voltage is applied from the drive circuit.

  Two contact portions 20 that come into contact with the outer peripheral surface 31 of the rotor 30 are formed at the end of the stator body 15 on the rotor 30 side. Each contact portion 20 is in contact with the outer peripheral surface 31 of the rotor 30 at the contact surface 21. Between the two contact portions 20, a groove portion 19 is formed that traverses in the radial direction. The groove portion 19 forms a space portion in which a part of the bearing member 37 that supports the rotating shaft 34 is accommodated.

  The rotor 30 includes an outer peripheral surface 31 and a pair of rotor end surfaces 32. A rotation shaft 34 is fixed to the center of the rotor 30. The axis of the rotation shaft 34 is the rotation axis P of the rotor 30. Both ends of the rotating shaft 34 are output ends of the vibration actuator 1, and the rotational force of the rotating shaft 34 is used as an output.

  The bearing member 37 includes a pair of bearing portions 38 provided on both sides of the rotor end surface 32 and a connection portion 39 that connects the pair of bearing portions 38. A through hole 40 is formed in the bearing portion 38, the rotary shaft 34 is inserted through the through hole 40, and the rotary shaft 34 is rotatably supported by the bearing portion 38 via a bearing 36.

  As shown in FIG. 2, the connecting portion 39 of the bearing member 37 is connected to one end portion of the connecting rod 45. The connecting rod 45 is inserted into the through hole 22 of the stator 13, and the other end of the connecting rod 45 protrudes from the shaft portion 14 of the stator 13. Accordingly, the connecting rod 45 passes through the stator 13 and the piezoelectric element 17. A disc-shaped spring receiver 49 is attached to the protruding end 47 of the connecting rod 45 via a holder 48. A disc spring 50 is interposed between the spring receiver 49 and the base 11. In the present embodiment, the protruding end 47, the holder 48, the spring receiver 49, and the disc spring 50 are accommodated in a thin cylindrical cylindrical portion 11 </ b> A provided in the base 11.

  The disc spring 50 presses the base 11 of the vibrating body 10 toward the rotor 30. Thereby, the rotor 30 is brought into pressure contact with the stator 13 of the vibrating body 10. That is, in the present embodiment, the connecting rod 45, the spring receiver 49, and the disc spring 50 are elements that constitute a preload portion that pressurizes and contacts the rotor 30 with the stator 13.

  In the present embodiment, the vibration actuator 1 is selectively used as an ultrasonic motor or a force sensor.

  When the vibration actuator 1 is used as an ultrasonic motor, the rotating shaft 34 is rotated using the inverse piezoelectric effect (a phenomenon that deforms when a voltage is applied) of the piezoelectric element 17. Specifically, by applying an AC voltage (more specifically, an AC voltage whose phase is shifted by 90 degrees) from the drive circuit to the piezoelectric element 17, the piezoelectric element 17 is ultrasonically vibrated (more specifically, in the Y-axis direction). Composite vibration combining the flexural vibration and the longitudinal vibration in the Z-axis direction). This ultrasonic vibration is transmitted to the stator 13, and an elliptical motion (or circular motion) around the X axis in the Y-axis / Z-axis plane occurs on the pair of contact surfaces 21 in the stator 13. When the rotor 30 receives an elliptical motion (or a circular motion) through the contact surface 21, the rotor 30 is rotated about the rotation axis 34. The rotational force of the rotating shaft 34 is obtained by the rotation of the rotor 30. The control of the rotation direction, rotation speed, and torque of the rotor 30 can be changed by controlling the applied AC voltage, frequency, and the like.

  On the other hand, when the vibration actuator 1 is used as a force sensor, the force acting on the rotating shaft 34 is detected using the piezoelectric effect of the piezoelectric element 17 (a phenomenon that generates a voltage when deformed by an external force). For example, when an object is pushed by a link (fingertip) attached to the rotation shaft 34, a reaction force from the object acts on the rotation shaft 34 via the link (fingertip). This reaction force is transmitted from the rotor 30 to the stator 13 through the contact surface 21. As a result, the piezoelectric element 17 receives an external force corresponding to a reaction force (force acting on the rotating shaft 34) from the object from the stator 13. When the piezoelectric element 17 is deformed by the external force, the piezoelectric element 17 generates a voltage corresponding to the deformation amount. By measuring the voltage of the piezoelectric element 17, the force acting on the rotating shaft 34 is detected.

  When the vibration actuator 1 is used as a force sensor, in order to increase the detection accuracy, the vibrating body 10 is moved by the force acting on the rotor 30 so that the piezoelectric element 17 is deformed according to the force acting on the rotor 30. It is desirable to fix so that there is no. However, when the vibrating body 10 is fixed constantly, the vibration of the stator 13 is hindered, so that the output performance (torque, rotational speed, efficiency, etc.) of the vibration actuator 1 as an ultrasonic motor is reduced. Thus, ensuring the detection accuracy as the force sensor and securing the output performance as the ultrasonic motor are in a trade-off relationship with each other.

  The vibration actuator 1 according to the present embodiment pressurizes the vibrating body 10 in order to achieve both the detection accuracy as a force sensor and the output performance as an ultrasonic motor, which have such a trade-off relationship. A support member for supporting is provided. In the present embodiment, as shown in FIGS. 1 and 3, two flanges (beam members) 61 that protrude from the inner peripheral surface of the cover 60 and pressurize and support the vibrating body 10 are provided as support members. In the present embodiment, two flanges 61 are provided, but the number of flanges 61 may be three or more.

  4 is a view showing a cross section taken along the line IV-IV in FIG. When the vibration actuator 1 is used as a force sensor (that is, when the rotor 30 is not rotating), the two flanges 61 support the base 11 of the vibrating body 10 in a fixed manner, and the vibration actuator 1 is used as an ultrasonic motor ( That is, it is composed of an elastic member that movably supports the base 11 of the vibrating body 10 when the rotor 30 rotates.

  Specifically, each flange 61 includes a base end portion 61 </ b> A that is fixed to the inner peripheral surface of the cover 60, an arm portion that extends along the outer peripheral surface of the vibrating body 10, and a distal end that contacts the outer peripheral surface of the vibrating body 10. Part 61B. Here, the arm portion extending along the outer circumferential surface of the vibrating body 10 not only has a configuration extending in a curved shape along the outer circumferential surface of the vibrating body 10 as in the present embodiment, but also along the outer circumferential surface of the vibrating body 10. A configuration that extends linearly or a configuration that includes both a curved portion and a straight portion may be used. The front end portions 61B of the two flanges 61 support the base portion 11 under pressure by sandwiching the base portion 11 by the elastic force caused by the deflection of the entire flange 61. In the present embodiment, the distal end portion 61B of the flange 61 is placed on the antinode of the vibration of the base portion 11 when the vibrating body 10 vibrates when the vibration actuator 1 is used as a force sensor (when the rotor 30 is not rotating). Support the corresponding part. Further, the base end portion 61A of the flange 61 is fixed to a portion corresponding to a vibration node of the cover 60 when the vibrating body 10 vibrates. The vibration of the vibrating body 10 is also slightly transmitted to the cover 60 through the rotor 30 and the bearing member 37.

  By providing such a flange 61, when the vibration actuator 1 is used as a force sensor, the vibrating body 10 is fixedly supported with respect to the cover 60 (and the bearing member 37 to which the cover 60 is fixed). The Thereby, the detection accuracy as a force sensor is securable.

  In particular, the flange 61 according to the present embodiment is not the stator 13 (the one closer to the rotor 30 than the piezoelectric element 17) among the stator 13 and the base 11 sandwiching the piezoelectric element 17, but the base 11 (the rotor more than the piezoelectric element 17). The person who is far from 30). Therefore, when the force acting on the rotor 30 acts on the piezoelectric element 17 from the stator 13, the piezoelectric element 17 can be firmly received by the base 11. Therefore, since the piezoelectric element 17 is easily deformed according to the external force from the stator 13, the detection accuracy can be further increased.

  Furthermore, the flange 61 movably supports the vibrating body 10 with respect to the cover 60 when the vibration actuator 1 is used as an ultrasonic motor. Specifically, the flange 61 absorbs the vibration of the base 11 by resonating with the base 11 of the vibrating body 10 when the vibration actuator 1 is used as an ultrasonic motor.

  FIG. 5 is a diagram illustrating the frequency characteristics of the flange 61. In FIG. 5, the horizontal axis represents frequency, and the vertical axis represents Q value (a value representing the sharpness of resonance).

  As shown in FIG. 5, the flange 61 has a maximum Q value at the vibration frequency f1 of the vibrating body 10 when the vibration actuator 1 is used as an ultrasonic motor, and a Q value in a region away from the vibration frequency f1. The characteristic is almost zero. The shape (length, thickness, etc.) of the flange 61 is determined in advance so as to have such frequency characteristics.

  Therefore, when the vibration actuator 1 is used as an ultrasonic motor, the flange 61 resonates with the base 11 and absorbs the vibration of the base 11. That is, the vibration of the vibrating body 10 is not hindered by the flange 61 (further, the cover 60 to which the flange 61 is fixed and the bearing member 37 to which the cover 60 is fixed). As a result, output performance (torque, speed, efficiency, etc.) as an ultrasonic motor is also ensured.

  In particular, in the present embodiment, as described above, the distal end portion 61B of the flange 61 supports a portion corresponding to the vibration antinode of the base portion 11. Thereby, since the flange 61 becomes easier to resonate, the vibration of the base portion 11 can be absorbed more positively.

  As described above, when the vibration actuator 1 is used as a force sensor (when the rotor 30 is not rotating), the flange 61 according to the present embodiment fixedly supports the vibrating body 10 by the elastic force due to the deflection, and vibrates. When the actuator 1 is used as an ultrasonic motor (when the rotor 30 is rotating), it resonates with the vibrating body 10 to support the vibrating body 10 so as to vibrate. Therefore, it is possible to ensure the output performance when the vibration actuator 1 is used as an ultrasonic motor while ensuring the detection accuracy when the vibration actuator 1 is used as a force sensor.

  In addition, since the force sensor and the ultrasonic motor can be integrated by using the vibration actuator 1, for example, when the vibration actuator 1 is used in a robot hand, the robot hand can be reduced in size, weight, and cost. it can.

<Modification 1 of Support Member>
In the above-described embodiment, the flange (beam member) 61 is employed as the support member that pressurizes and supports the vibrating body 10, but the support member is not limited to this.

  For example, a plunger 70 as shown in FIG. 6 may be employed as the support member. As the plunger 70, a known ball plunger or the like can be used. 6 shows three plungers 70, the number of plungers 70 may be two or four or more.

  Each plunger 70 is a rod-like member that is rotatably supported by the inner peripheral surface of the cover 60 and can be elastically expanded and contracted in the longitudinal direction. Specifically, each plunger 70 includes a hollow rod-like main body 71 and a tip 72 that is movably supported in the longitudinal direction of the main body 71 by an elastic body (not shown) provided inside the main body 71. , And a base end portion 73 that rotatably supports the main body portion 71 on the inner peripheral surface of the cover 60.

  The vicinity of the tip of the main body 71 of each plunger 70 is supported on the inner peripheral surface of the cover 60 by a plurality of coil springs 74. The coil spring 74 may be changed to another elastic body (for example, a disc spring).

  FIG. 7 is a diagram illustrating the state of the plunger 70 when the vibrating body 10 vibrates (when the rotor 30 rotates) and when the vibrating body 10 does not vibrate (when the rotor 30 does not rotate). 7 is a view showing a VII-VII cross section of FIG.

  When the vibrating body 10 is not vibrating, the plunger 70 is held by the elastic force of the plurality of coil springs 74 such that the distal end portion 72 is in pressure contact with a predetermined portion (hereinafter referred to as “origin”) of the base portion 11. Thereby, the base 11 of the vibrating body 10 is fixedly supported by the three plungers 70. In the present embodiment, the arrangement of the plungers 70 is adjusted in advance so that the origin is the position of the antinode of the vibration of the base 11 when the vibrating body 10 vibrates.

  On the other hand, since the distal end portion 72 is configured to be movable with respect to the surface of the vibrating body 10 when the vibrating body 10 vibrates, the vibration of the base portion 11 is transmitted to the plunger 70, so that each plunger 70 includes a plurality of plungers 70. The tip 72 moves in the direction from the origin toward the vibration node of the base 11 along the surface of the vibrating body 10 against the elastic force of the coil spring 74. Thereby, compared with the case where the plunger 70 continues to support the origin (vibration antinode), the vibrating body 10 can be supported in a state where the vibration of the vibrating body 10 is allowed.

  Further, when the vibration of the vibrating body 10 is stopped (when the rotation of the rotor 30 is stopped), the distal end portion 72 of the plunger 70 returns to the origin again by the elastic force of the plurality of coil springs 74.

  As described above, when the vibration actuator 1 is used as a force sensor (when the rotor 30 is not rotating), the plunger 70 according to the present modification causes the tip 72 to press-contact the vibrating body 10 so that the vibrating body 10 is moved. When the vibration actuator 1 is used as an ultrasonic motor (when the rotor 30 rotates), the tip 72 moves on the surface of the vibration body 10 toward the vibration node of the vibration body 10 when the vibration actuator 1 is used as an ultrasonic motor. The vibrating body 10 is supported so as to be able to vibrate. Therefore, as in the case of using the flange 61 described above, it is possible to ensure the output performance when the vibration actuator 1 is used as an ultrasonic motor while ensuring the detection accuracy when the vibration actuator 1 is used as a force sensor. .

<Modification 2 of Support Member>
Further, instead of the flange 61 according to the above-described embodiment, a support member 80 as shown in FIGS. 8 and 9 may be employed as the support member. 8 and 9, two support members 80 are shown, but the number of support members 80 may be three or more.

  Each support member 80 includes a plate-like member 81 and a plurality of disc springs 82. The disc spring 82 may be changed to another elastic body (for example, a coil spring).

  The plate-like member 81 is formed so as to be able to come into surface contact with the outer peripheral surface of the cylindrical portion 11A of the base portion 11. A contact surface of the plate-like member 81 with the cylinder portion 11A has a predetermined area in order to secure a levitation force described later. The disc spring 82 is provided between the plate-like member 81 and the inner peripheral surface of the cover 60, and presses the plate-like member 81 toward the cylinder portion 11A.

  FIG. 9 is a diagram illustrating the state of the plate-like member 81 when the vibrating body 10 vibrates (when the rotor 30 rotates) and when the vibrating body 10 does not vibrate (when the rotor 30 does not rotate). FIG. 9 is a view showing a IX-IX cross section of FIG.

  When the vibrating body 10 is not vibrating, the plate-like member 81 is held in a state in which the cylindrical portion 11 </ b> A is pressed and supported by the elastic force of the disc spring 82.

  On the other hand, when the vibrating body 10 vibrates, the plate-like member 81 receives a levitation force from the cylindrical portion 11A by the near-field acoustic wave levitation action. That is, when the cylinder portion 11 </ b> A is ultrasonically vibrated, a force called radiation pressure is generated at the boundary surface between the cylinder portion 11 </ b> A and the plate-like member 81, and a levitation force due to this radiation pressure acts on the plate-like member 81. Since the near-field acoustic wave levitation itself is well known, detailed description thereof will not be repeated here.

  The plate-like member 81 is held at a position where the levitation force due to the near-field acoustic wave levitation action and the elastic force of the disc spring 82 are balanced. As a result, the plate member 81 is lifted from the cylindrical portion 11A and is not in contact with the plate member 81 as shown by the alternate long and short dash line in FIG. 9, so that the friction between the plate member 81 and the cylindrical portion 11A becomes zero. Can vibrate. At this time, the cylindrical portion 11 does not come into contact with the plate-like member 81, but receives a reaction force of the levitation force from the plate-like member 81. By this reaction force, the cylindrical portion 11 is supported by the plate-like member 81 (and the cover 60 on which the plate-like member 81 is supported).

  Thus, when the vibration actuator 1 is used as a force sensor (when the rotor 30 is not rotating), the plate-like member 81 according to this modification is pressed against the cylindrical portion 11A of the base 11 by the elastic force of the disc spring 80. When the vibrating body 10 is fixedly supported by contact and the vibration actuator 1 is used as an ultrasonic motor (when the rotor 30 rotates), it floats from the cylindrical portion 11A of the base 11 by the near-field acoustic wave levitation action. Thus, the vibrating body 10 is supported so as to be able to vibrate. Therefore, as in the case of using the flange 61 described above, it is possible to ensure the output performance when the vibration actuator 1 is used as an ultrasonic motor while ensuring the detection accuracy when the vibration actuator 1 is used as a force sensor. .

  In addition, the plate-shaped member 81 does not necessarily have to be lifted completely from the cylinder portion 11A. In other words, even if the levitation force is not completely lifted, the force with which the plate-like member 81 presses the cylinder portion 11A due to the levitation force is reduced, so that the friction between the plate-like member 81 and the cylinder portion 11A is reduced. Thereby, the vibrating body 10 can be easily vibrated.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Vibrating actuator, 10 Vibrating body, 11 Base part, 11A Tube part, 12 Screw hole, 13 Stator, 14 Shaft part, 15 Stator main body part, 16 Male screw, 17 Piezoelectric element, 18, 40 Through-hole, 19 Groove part, 20 Contact part , 21 Contact surface, 22 Through hole, 30 Rotor, 31 Outer peripheral surface, 32 Rotor end surface, 34 Rotating shaft, 37 Bearing member, 38 Bearing portion, 39 Connection portion, 45 Connecting rod, 47 Protruding end, 48 Holder, 49 Spring support Body, 50, 80, 82 Disc spring, 60 cover, 61 flange, 61A proximal end, 61B distal end, 70 plunger, 71 main body, 72 distal end, 73 proximal end, 74 coil spring, 80 support member, 81 Plate member.

Claims (10)

A rotor,
A vibrating body configured to include a piezoelectric element that contacts the rotor and generates ultrasonic vibration for rotating the rotor on a contact surface with the rotor;
A cover provided around the vibrating body and fixed to a member that rotatably supports the output shaft of the rotor;
A support member provided between the cover and the vibrator and supporting the vibrator under pressure,
The vibration member is configured to support the vibration body fixedly with respect to the cover when the rotor does not rotate, and to support the vibration body so that the vibration body can vibrate when the rotor rotates.   The support member supports the vibrating body fixedly with respect to the cover by an elastic force when the rotor is not rotating, and supports the vibrating body so as to vibrate by resonating with the vibrating body when the rotor rotates. The vibration actuator according to claim 1. The support member is a beam-like member including a base end fixed to the cover, an arm portion extending along an outer peripheral surface of the vibrating body, and a distal end contacting the vibrating body,
The said beam-like member fixedly supports the vibrating body with respect to the cover by elastic force due to deflection when the rotor is not rotating, and resonates with the vibrating body when the rotor is rotating. Vibration actuator.   4. The vibration actuator according to claim 2, wherein the support member supports a portion corresponding to an antinode of vibration during resonance of the vibrating body when the rotor is not rotating. 5. The support member is a rod-like member that is elastically stretchable in the longitudinal direction, and has a base end rotatably supported inside the cover and a distal end configured to be movable with respect to the vibrating body.
The rod-shaped member supports the vibrating body fixedly with respect to the cover by having the tip press-contact with a predetermined portion of the vibrating body when the rotor is not rotating, and the vibrating body when the rotor is rotating. 2. The vibration actuator according to claim 1, wherein the tip that comes into contact with the vibrator moves along the surface of the vibrator from the predetermined portion so as to vibrate the vibrator. The support member further includes an elastic body for a rod-shaped member that holds the rod-shaped member so that the tip of the rod-shaped member is in contact with the predetermined portion of the vibrating body when the rotor is not rotating,
The elastic body for the rod-shaped member allows the tip of the rod-shaped member to move along the surface of the vibrating body when the rotor rotates, while the tip of the rod-shaped member does not move when the rotor does not rotate. The vibration actuator according to claim 5, wherein the rod-shaped member is supported so as to return to a predetermined portion.   The vibration actuator according to claim 5, wherein the predetermined portion is a portion corresponding to an antinode of vibration at the time of resonance of the vibrating body. The support member includes a plate-like member formed so as to be in contact with an outer peripheral surface of the vibrating body, and an elastic body for a plate-like member that presses the plate-like member against the vibrating body,
The plate-like member fixedly supports the vibrating body with respect to the cover by being in pressure contact with the vibrating body by the elastic force of the plate-like member elastic body when the rotor is not rotating, and the rotor 2. The vibration actuator according to claim 1, wherein the vibration body is supported so as to be able to vibrate by receiving a levitation force from the vibration body by a near-field acoustic wave levitation action when rotating. The support member is composed of a plurality of supports whose base ends are supported inside the cover,
The vibration actuator according to claim 1, wherein the support member pressurizes and supports the vibrating body by sandwiching the vibrating body with the plurality of support bodies when the rotor is not rotating. The vibrator is
A stator in contact with the rotor;
A base portion provided integrally with the stator and disposed so as to sandwich the piezoelectric element with the stator;
A preload portion that pressurizes and contacts the rotor with the stator;
The vibration actuator according to claim 1, wherein the support member supports the base portion of the vibrating body.

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