JP2013165612A - Vibration actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration actuator that is capable of smoothly operating and generating a high torque even when it is used for a long period of time.SOLUTION: A vibration actuator 101 includes: a rotor 1; a stator 2 that is capable of contacting the rotor 1; a preload member 8 that brings the rotor 1 and the stator 2 into pressure contact with each other; and a piezoelectric element that moves the stator 2 by generating ultrasonic vibration in the rotor 1, wherein a hardness ratio (A/B) between hardness (A) of the rotor 1 and hardness (B) of the stator 2 is larger than one and is equal to or smaller than 20.

Description

  The present invention relates to a vibration actuator that drives a moving element using ultrasonic vibration generated in a vibrator.

  In recent years, there has been realized a vibration actuator that generates ultrasonic vibrations in a vibrator including a piezoelectric element and the like, and drives a movable element in pressure contact with the vibrator by a frictional force between both members. Here, in the case where the vibration actuator is driven for a long period of time, a portion that slides and rubs at a high frequency appears particularly in a portion where the moving element contacts the vibrator. Of the surface of the moving element, the portion that slides with the vibrator frequently has a higher degree of wear than the other portions. As a result, the surface of the moving element has a portion with a large amount of wear and a portion with a small amount of wear, and a step or an unevenness is formed at the boundary between the two. May be hindered.

  In view of such a problem, for example, in the vibration actuator of Patent Document 1, the hardness of the sliding part of the rotor (moving element) is made larger than the hardness of the end part of the stator (vibrating element), so that the rotor (moving element) ) Deformation is prevented.

JP 2000-245179 A

  As described above, it is necessary to prevent the movement of the moving element in order to smooth the operation of the vibration actuator over a long period of use and to prolong the life of the vibration actuator. On the other hand, it is desirable that the vibration actuator has as high a driving force as possible. In particular, for example, when a vibration actuator is used for a joint of a robot hand or the like, a high driving force is required to directly drive the output member. That is, it is necessary to apply a high preload in order to improve the driving force of the vibration actuator.

  However, as can be seen in Patent Document 1, in a vibration actuator used for a watch or a camera, the moving element is made of super steel, ruby, iron, ceramic or the like as a material, or is subjected to a hardening process. . On the other hand, the vibrator is made of a resin material such as polyimide resin, fluororesin, or nylon. For this reason, the hardness difference between the moving element and the vibrator is extremely large, and when a high preload is applied, the vibrator is worn or deformed. Therefore, the vibration actuator of Patent Document 1 applies only a low preload and cannot apply a high preload, and therefore cannot provide a high torque.

  The present invention has been made to solve such problems, and an object of the present invention is to provide a vibration actuator that realizes both a long life and a high torque of the vibration actuator.

  The vibration actuator according to the present invention includes a moving element, a vibrator that can contact the moving element, a preload means that pressurizes the moving element and the vibrator, and an ultrasonic vibration generated in the vibrator. And a moving member having a moving member side contact surface that can come into contact with the vibrator, and a vibrator having a vibrator side contact surface that can come into contact with the moving member side contact surface. The hardness ratio (A / B) between the hardness (A) of the side contact surface and the hardness (B) of the vibrator side contact surface is greater than 1 and 20 or less.

  In the vibration actuator according to the present invention, the hardness ratio (A / B) between the hardness (A) of the slider-side contact surface and the hardness (B) of the vibrator-side contact surface is greater than 1 and 5 or less. Also good.

When at least one of the rotor 1 and the stator 2 is subjected to surface treatment, the hardness of the contact surface may be the hardness of the base material subjected to the surface treatment according to a predetermined condition.
That is, depending on predetermined conditions, the ratio (a ″ / b ″) of the hardness (a ″) of the slider side base material to the hardness (b ″) of the vibrator side base material is greater than 1 and 20 or less. There may be. Further, the ratio (a ″ / B) between the hardness (a ″) of the movable member side base material and the hardness (B) of the vibrator side contact surface may be greater than 1 and 20 or less. Still further, the ratio (A / b ″) of the hardness (A) of the slider side contact surface and the hardness (b ″) of the vibrator side base material may be greater than 1 and 20 or less.

  Also, a lubricant supply means capable of supplying a liquid lubricant between the moving element and the vibrator is provided, and the lubricant supply body is impregnated with the liquid lubricant and can contact at least one of the moving element and the vibrator. It can also be a supply body provided in the case.

  According to the present invention, it is possible to achieve both smooth operation and high torque in the long-term use of the vibration actuator.

It is a perspective view which shows the structure of the vibration actuator which concerns on Embodiment 1 or 2 of this invention. FIG. 2 is a conceptual diagram of the vibration actuator shown in FIG. 1 when the vertical axis represents the rotor torque and the horizontal axis represents the rotor hardness / stator hardness ratio. For the vibration actuator shown in FIG. 1, the volume of the piezoelectric element is taken on the x axis, the frictional force acting between the rotor and the stator is taken on the y axis, and the preload is taken on the z axis. It is a conceptual diagram expressed as torque. It is a perspective view which shows the structure of the vibration actuator which concerns on Embodiment 3 of this invention.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
Embodiment 1 FIG.
FIG. 1 shows a vibration actuator 101 according to the first embodiment. The vibration actuator 101 rotates the substantially cylindrical rotor 1 around the axial direction (see arrows P and Q) using ultrasonic vibration, and is in contact with the rotor 1 on one end side. 2 is provided. In addition, a piezoelectric element 3 that causes the stator 2 to generate ultrasonic vibration, a first base block 4, and a second base block 5 are sequentially provided on the other end side of the stator 2. The piezoelectric element 3 is formed by laminating a plurality of piezoelectric element plates, and ultrasonic vibration is generated in the stator 2 when an AC voltage is applied to these piezoelectric element plates from a drive circuit (not shown). The stator 2 and the piezoelectric element 3 as a whole have a substantially cylindrical outer shape, and the axial direction of the rotor 1 and the axial direction of the stator 2 and the piezoelectric element 3 are orthogonal to each other. Here, the rotor 1, the stator 2, and the piezoelectric element 3 constitute a moving element, a vibrator, and a vibrating means in the vibration actuator 101, respectively.

  The rotor 1 includes a first rotor member 1a and a second rotor member 1b having the same cylindrical shape, and a rotor shaft 1c penetrating through the central portions of these rotor members 1a and 1b. The first rotor member 1a and the second rotor member 1b are integrally fixed to both ends of the rotor shaft 1c. The first rotor member 1a and the second rotor member 1b are centered on the central axis of the rotor shaft 1c. The rotor shaft 1c rotates as a unit. Further, on the outer peripheral portion of the rotor 1, for example, when the vibration actuator 101 is applied as a robot hand, a columnar arm member 6 serving as a member constituting the arm portion or the finger portion is provided. The arm member 6 is fixed to the outer peripheral surface 1aa of the first rotor member 1a and the outer peripheral surface 1ba of the second rotor member 1b, respectively, so that the rotor 1 and the arm member 6 can rotate together.

Here, for convenience of the following description, the central axis of the stator 2 and the piezoelectric element 3 is defined as the Z axis, and the positive direction is the direction from the second base block 5 side toward the stator 2 side. The central axis of the rotor shaft 1c orthogonal to the Z axis is defined as the X axis, and the Y axis is defined to extend so as to be orthogonal to the Z axis and the X axis.
A pair of first projecting claw portions 2a and second projecting claw portions 2b projecting in the positive direction along the Z axis and extending linearly along the X axis are formed at the end of the stator 2 on the rotor 1 side. Has been. An arc-shaped cross section along the outer circumferential surface 1aa of the first rotor member 1a and the outer circumferential surface 1ba of the second rotor member 1b at the inner side, that is, the portion located on the concave portion 2c side, at the tip of the first protruding claw portion 2a A first abutment surface 2a1 is formed. The first contact surface 2a1 has a pair of first contact surfaces 2a2, and is in contact with the outer peripheral surface 1aa of the first rotor member 1a and the outer peripheral surface 1ba of the second rotor member 1b at the first contact surface 2a2. . Similarly, a second abutting surface 2b1 having a cross section similar to that of the first abutting surface 2a1 is also formed at a portion located on the inner side at the tip of the second protruding claw portion 2b. Further, the second contact surface 2b1 has a pair of second contact surfaces 2b2, and in contact with the outer peripheral surface 1aa of the first rotor member 1a and the outer peripheral surface 1ba of the second rotor member 1b at the second contact surface 2b2. Yes. That is, the stator 2 includes the first rotor member 1a and the second rotor member 1b of the rotor 1 on the first contact surface 2a1 of the first protrusion claw portion 2a and the second contact surface 2b1 of the second protrusion claw portion 2b. Contact is possible.
Here, the outer peripheral surface 1aa of the first rotor member 1a and the outer peripheral surface 1ba of the second rotor member 1b constitute a moving element side contact surface. The moving element side contact surface is a portion where the rotor 1 can contact the stator 2 in accordance with the rotational movement range of the rotor 1. In the present embodiment, the slider-side contact surface refers to the entire outer peripheral surface 1aa and the entire outer peripheral surface 1ba excluding the attachment portion of the arm member 6.
Further, the first contact surface 2a2 and the second contact surface 2b2 constitute a vibrator side contact surface. The vibrator side contact surface refers to a portion of the stator that can contact the rotor.

  In addition, a substantially rectangular parallelepiped supply body 10 impregnated with lubricating oil as a lubricant is provided in a recess 2c formed between the first protruding claw portion 2a and the second protruding claw portion 2b. The supply body 10 is obtained by impregnating a porous resin member having flexibility and / or elasticity with a lubricant such as a lubricating oil such as oil or grease. As the lubricating oil, for example, fluorine-based, glycol-based, synthetic hydrocarbon-based, or ester-based oil or grease can be used. The supply body 10 constitutes a lubricant supply means.

  Further, the vibration actuator 101 includes a preload member 8 for bringing the rotor 1 and the stator 2 into pressure contact. The preload member 8 has a shaft portion 8a extending along the Z-axis at the center portion of the stator 2 and the piezoelectric element 3. One end of the shaft portion 8a protrudes from the stator 2 and extends between the first rotor member 1a and the second rotor member 1b of the rotor 1, and is attached to surround the outer periphery of the rotor shaft 1c so as to be rotatably supported. It is connected to the portion 8b. On the other hand, the other end of the shaft portion 8a extends into the second base block 5 and is connected to an urging portion 8c configured by a coil spring or the like. The urging portion 8c urges the rotor shaft 1c in the direction indicated by the arrow F (the negative direction of the Z axis) via the shaft portion 8a and the attachment portion 8b, whereby the rotor 1 and the stator 2 are It comes to come into pressure contact. Here, the preload member 8 including the shaft portion 8a, the attachment portion 8b, and the urging portion 8c constitutes a preload means in the vibration actuator 101.

Next, the operation of the vibration actuator according to Embodiment 1 of the present invention will be described.
As shown in FIG. 1, first, when an AC voltage is applied from a drive circuit (not shown) to a plurality of piezoelectric element plates of the piezoelectric element 3, each piezoelectric element plate generates ultrasonic vibrations having different vibration directions. To do. When these ultrasonic vibrations are transmitted to the stator 2 as composite vibrations, elliptical vibrations around the X axis are generated at the tips of the first protruding claw portion 2a and the second protruding claw portion 2b of the stator 2. Further, traveling waves due to elliptical vibration around the X axis are generated on the first contact surface 2a1 of the first projecting claw portion 2a and the second contact surface 2b1 of the second projecting claw portion 2b, and these contact surfaces 2a1. 2b1 and the frictional force acting between the outer circumferential surface 1aa of the first rotor member 1a of the rotor 1 and the outer circumferential surface 1ba of the second rotor member 1b, the rotor 1 and the arm member 6 are indicated by arrows P or Q. Rotated in the direction Note that the rotation direction of the rotor 1 is controlled according to the AC voltage applied to each piezoelectric element plate of the piezoelectric element 3.
The ultrasonic vibration generated by the piezoelectric element 3 is the vibration vibration having the largest amplitude in the ultrasonic vibration transmitted from the piezoelectric element 3 to the vibrator 2, or the vicinity of the vibration antinode is the vibration of the vibrator 2. The positions of the first contact surface 2a1 of the first projecting claw portion 2a and the second contact surface 2b1 of the second projecting claw portion 2b, that is, included in the first contact surface 2a1 and the second contact surface 2b1. As described above, the phase of vibration is controlled by controlling the AC voltage applied to the piezoelectric element 3. For this reason, the amplitude of the ultrasonic vibration is large at the first contact surface 2a1 and the second contact surface 2b1 at or near the position of the vibration antinode, that is, the vibration is large.

  In addition, the outer peripheral surface 1aa of the first rotor member 1a and the outer peripheral surface 1ba of the second rotor member 1b are supplied with lubricating oil held by the lubricating member 10 due to the pumping effect of surface tension by contacting the lubricating member 10. The Further, the lubricating oil supplied from the lubricating member 10 to the outer peripheral surfaces 1aa and 1ba gathers on the contact surfaces with the first contact surface 2a1 and the second contact surface 2b1 of the vibrator 2 where the vibration is greatest. Therefore, the lubricating oil permeates the entire contact area between the outer peripheral surface 1aa and the outer peripheral surface 1ba and the first contact surface 2a1 and the second contact surface 2b1 to form an oil film.

Next, the hardness ratio between the rotor 1 and the stator 2 will be described with reference to FIG. FIG. 2 is a graph conceptually showing the relationship between the ratio (A / B) of the hardness (A) of the rotor 1 and the hardness (B) of the stator 2 and the torque of the rotor. The hardness of the rotor 1 and the stator 2 is measured based on the same index by a general hardness tester. The hardness in the present embodiment is a value based on Vickers hardness, but Rockwell hardness or the like may be used.
In this graph, ceramic is used as the material of the rotor 1, and the Vickers hardness is HV1700. In FIG. 2, (i) shows a case where ceramic is used as the material of the stator 2. Moreover, as a material of the stator 2, (ii) shows the case where carbon steel is used, and (iii) shows the case where aluminum is used.
2 indicates a region where the ratio (A / B) between the hardness (A) of the rotor 1 and the hardness (B) of the stator 2 is greater than 1 and not greater than 5. Here, in the present embodiment, the ratio (A / B) between the hardness (A) of the rotor 1 and the hardness (B) of the stator 2 takes a value greater than 1 and 5 or less, and the region (a) Represented in Further, (i) and (ii) described above are in the region (a).
Furthermore, the region (b) indicates a range where the hardness ratio (A / B) of both is greater than 1 and 20 or less. Here, (iii) is outside the region (a) and within the region (b), and the hardness ratio (A / B) when aluminum is used as the material of the stator 2 is greater than 5 and 20 or less.
(Iv) shows the ratio (A / B) between the hardness (A) of the rotor 1 and the hardness (B) of the stator 2 in a conventional vibration actuator using a resin material as the material of the stator 2, and the region (c) ) Indicates a range of hardness ratio (A / B) and torque that can be considered when a resin material is used for the rotor 1.

From the region (c) of FIG. 2, when a resin material is used as the material of the stator 2, the ratio (A / B) between the hardness (A) of the rotor 1 and the hardness (B) of the stator 2 becomes extremely large. It is clear that the required high torque cannot be obtained. That is, in the region (c), since the hardness (B) of the stator 2 is too low with respect to the hardness (A) of the rotor 1, only a preload of 10 N or less can be applied, and a high torque cannot be obtained. .
On the other hand, in the region (a), since the difference between the hardness (A) of the rotor 1 and the hardness (B) of the stator 2 is small and the hardness ratio (A / B) is small, a very high preload (300N to 600N). ). Therefore, a high torque that can directly drive the arm member 6 is generated in the vibration actuator 101.

Next, the difference between the torque of the vibration actuator 101 according to the present invention and the torque of a conventional vibration actuator using a resin material as the material of the stator 2 will be described with reference to FIG. Fig. 3 shows the volume of the piezoelectric element on the x-axis, the coefficient representing the relationship between the rotor and the stator on the y-axis, and the preload on the z-axis. This is conceptually expressed as the magnitude of the torque of the actuator. The coefficient representing the relationship between the rotor and the stator is a coefficient that varies depending on the degree of friction between the rotor and the stator and the degree of deformation. When the coefficient of friction is large, the coefficient increases as the deformation decreases.
Here, FIG. 3A shows the magnitude of torque of the vibration actuator in which the material of the stator 2 is a resin material. FIG. 3B shows the magnitude of torque of the vibration actuator 101 according to the present invention. As described above, the vibration actuator 101 in FIG. 3B has a lower preload than the vibration actuator in FIG. Since the vibration actuator shown in FIG. 3A is used for a timepiece or a camera as described above, the piezoelectric element is small. Furthermore, the coefficient representing the relationship between the stator and the rotor is small. Therefore, it can be seen that the vibration actuator 101 of FIG.

  As described above, in the vibration actuator 101, the ratio (A / B) between the hardness (A) of the rotor 1 and the hardness (B) of the stator 2 is set to be greater than 1 and 5 or less, so that the rotor 1 is worn. In addition, the smooth operation of the vibration actuator 101 is maintained even after long-term use. Further, the difference in hardness between the rotor 1 and the stator 2 is not too large, and a high preload can be applied. As a result, a high torque necessary for driving the arm member 6 can be obtained. That is, even when the vibration actuator 101 is used for a long period of time, both smooth operation and high torque can be achieved.

Embodiment 2. FIG.
Next, a vibration actuator 102 according to Embodiment 2 of the present invention will be described.
The vibration actuator 102 is a vibration actuator having the same configuration as that of the vibration actuator 101 of the first embodiment shown in FIG. 1, and the ratio (A / B) of the hardness (A) of the rotor 1 and the hardness (B) of the stator 2. Is greater than 5 and 20 or less. Accordingly, a detailed description of the overall configuration is omitted.

Here, the ratio (A / B) between the hardness (A) of the rotor 1 and the hardness (B) of the stator 2 in the vibration actuator 102 is, as described above, in the region (b) (region ( It is expressed in (except a). Accordingly, also in the present embodiment, since the difference between the hardness (A) of the rotor 1 and the hardness (B) of the stator 2 is small and the hardness ratio (A / B) is small, it is possible to apply a high preload of 100 N or more. it can. Therefore, a high torque that can drive the arm member 6 directly is generated in the vibration actuator 102.
Further, although the torque generated in the vibration actuator 102 is smaller than the torque generated in the vibration actuator 101, it is less expensive than the vibration actuator 101 while maintaining the generation of torque necessary to directly drive the arm member 6. can do.

Embodiment 3 FIG.
As shown in FIG. 4, the vibration actuator 103 includes a rotor 31 that is a spherical moving element, and a stator 32 that is a vibrator that contacts the rotor 31. At the end portion of the stator 32 located on the rotor 31 side, three projecting claw portions 32a to 32c formed in a substantially annular shape are provided so as to project toward the rotor 31, and these projecting claw portions 32a. To 32c are formed with spherical contact surfaces 32a1 to 32c1 corresponding to the outer surface 31a of the rotor 31, respectively. In addition, a substantially cylindrical supply body 33 made of the same resin as that of the supply body 10 in Embodiment 1 is provided inside the recess 32d formed inside the protruding claw portions 32a to 32c. The supply body 33 is impregnated with the same lubricating oil as in the first embodiment. Further, a preload means 34 is disposed on the rotor 31, and the rotor 31 is pressed against the stator 32 by the preload means 34.
Here, the outer surface 31a of the rotor 31 constitutes a moving element side contact surface. In the present embodiment, the slider-side contact surface refers to the entire outer surface 31a, but is not limited thereto, and may be a part of the outer surface 31a as long as it is a portion that can contact the stator 32.
Further, the contact surfaces 32a1 to 32c1 constitute a vibrator side contact surface.

  Further, the ratio (A ′ / B ′) between the hardness (A ′) of the rotor 31 and the hardness (B ′) of the stator 32 is larger than 1 and not larger than 5 as in the first embodiment. Other configurations are the same as those in the first embodiment. Therefore, even if the vibration actuator 103 is configured to drive the spherical rotor 31, smooth operation can be maintained and high torque can be obtained even when used for a long period of time as in the first embodiment. It is supposed to be.

  In the first and second embodiments described above, each rotor, which is a moving element, is configured as a substantially cylindrical or spherical member, but the shape of the moving element is not limited to a cylindrical shape or a spherical shape. For example, a vibration actuator having a moving element having another shape, such as a vibration actuator that rotates an annular moving element around an axial direction, or a so-called linear vibration actuator that linearly moves a rod-like or columnar moving element. It is also possible to apply the present invention.

  In the first or second embodiment, the hardness may be adjusted by subjecting the outer peripheral surfaces 1aa and 1ba of the rotor 1 to hard thin film processing. When the range in which the rotor 1 can come into contact with the stator 2 in accordance with the rotational movement range of the rotor 1 (mover side contact surface) is a part of the outer peripheral surfaces 1aa and 1ba, the hard thin film treatment is applied only to this range. You can also. In addition, the entire outer peripheral surfaces 1aa and 1ba including the attachment portion of the arm member 6 can be subjected to hard thin film processing. For the hard thin film processing, a method of forming a ceramic surface layer having a thickness of 12 μm to 20 μm on the outer peripheral surface of the rotor by thermal spraying of ceramic is conceivable, but the present invention is not limited to this, and other hard thin film processing methods may be used. The same applies to the outer surface 31a of the rotor 31 in the third embodiment. Here, the thin film formed by the hard thin film process on the outer peripheral surfaces 1aa and 1ba of the rotor 1 constitutes the moving member side surface layer. Moreover, the rotor 1 in which the hard thin film processing is performed on the outer peripheral surfaces 1aa and 1ba constitutes the moving member side base material with respect to the moving member side surface layer.

  In the first or second embodiment, the adjustment of the hardness between the slider-side contact surface and the vibrator-side contact surface is performed on the protruding claw portions 2a, 2b, the contact surfaces 2a1, 2b1, and the contact surfaces 2a2, 2b2 of the stator 2. You may give a hard thin film process. The contact surfaces 2a1, 2b1 and contact surfaces 2a2, 2b2 constitute a sliding surface. Here, the thin film formed by the hard thin film processing on the protruding claw portions 2a, 2b and the sliding surfaces 2a1, 2a2, 2b1, 2b2 of the stator 2 constitutes the vibrator side surface layer. Further, the stator 2 in which the hard claws are applied to the protruding claw portions 2a, 2b and the sliding surfaces 2a1, 2a2, 2b1, 2b2 constitutes a vibrator side base material with respect to the vibrator side surface layer. The hard thin film treatment may be applied not only to the entire protruding claw portions 2a and 2b but also only to the sliding surfaces 2a1, 2a2, 2b1, and 2b2.

Furthermore, when the hard thin film treatment is performed on the outer peripheral surfaces 1aa and 1ba of the rotor 1 in the first or second embodiment, the hardness (A) of the contact surface on the moving element side is determined according to predetermined conditions. The hardness (a ") of the base material works predominantly rather than '). The same applies when the protruding claw portions 2a, 2b and the sliding surfaces 2a1, 2a2, 2b1, 2b2 of the stator 2 are subjected to hard thin film processing. Here, the predetermined condition means, for example, when the thickness of the thin film is equal to or less than the total value of the deformation amount of each member and the amplitude value of the ultrasonic vibration (10 μm or less).
Therefore, when the film thickness of the thin film formed on the outer peripheral surfaces 1aa and 1ba of the rotor 1 is 10 μm or less, the hardness (a ″) of the rotor 1 (mover side base material) and the stator 2 (vibration) The ratio (a ″ / b ″) to the hardness (b ″) of the child side base material) needs to be greater than 1 and 20 or less. In this case, if the stator 2 is also subjected to a hard thin film treatment having a film thickness larger than 10 μm, the hardness (a ″) of the rotor 1 (mover side base material) and the thin film formed on the stator 2 (vibrator side) The ratio (a ″ / b ′) to the hardness (b ′) of the surface layer is greater than 1 and 20 or less.
On the other hand, when the film thickness of the thin film on the outer peripheral surfaces 1aa and 1ba of the rotor 1 is larger than 10 μm, the hardness (a ′) of the thin film (mover side surface layer) on the rotor 1 side and the stator 2 (vibrator side base material) ) To the hardness (b ″) (a ′ / b ″) is greater than 1 and 20 or less. Further, in this case, when the film thickness of the thin film on the stator 2 side subjected to the hard thin film treatment is larger than 10 μm, the hardness (a ′) of the thin film on the rotor 1 side (moving element side surface layer) and the thin film on the stator 2 side The ratio (a ′ / b ′) to the hardness (b ′) of the (vibrator-side surface layer) is greater than 1 and 20 or less.
However, the predetermined conditions are not limited to the present embodiment, and can be appropriately set according to the surface treatment state and the like. The hardness ratio is preferably greater than 1 and 5 or less when higher torque is required.

  As described above, that is, when at least one of the rotor 1 and the stator 2 is subjected to a surface treatment, the hardness ratio of each contact surface can be determined according to the deformation amount of each member, the amplitude value of ultrasonic vibration, or the like. It may be appropriate, while on the other hand it may be appropriate to take the hardness ratio of each base material.

  DESCRIPTION OF SYMBOLS 1,31 Rotor (moving element), 2,32 Stator (vibrator), 3 Piezoelectric element (vibration means), 8 Preload member (preload means), 33 Supply body (lubricant supply means), 34 Preload means, 1aa, 1ba outer peripheral surface (mover side contact surface), 2a1 first contact surface (vibrator side contact surface), 2b1 second contact surface (vibrator side contact surface), 31a outer surface (mover side contact surface), 101, 102, 103 Vibration actuator.

Claims (4)

Mover,
A vibrator capable of contacting the moving element;
Preload means for pressurizing and contacting the moving element and the vibrator;
Vibration means for moving the moving element by generating ultrasonic vibration in the vibrator;
With
The slider has a slider-side contact surface that can contact the vibrator,
The vibrator has a vibrator-side contact surface that can come into contact with the slider-side contact surface,
A vibration actuator characterized in that a ratio (A / B) of the hardness (A) of the slider side contact surface and the hardness (B) of the vibrator side contact surface is greater than 1 and 20 or less.   2. The vibration actuator according to claim 1, wherein a ratio (A / B) of a hardness (A) of the moving element side contact surface and a hardness (B) of the vibrator side contact surface is greater than 1 and 5 or less.   2. When the surface treatment is applied to at least one of the movable element or the vibrator, the hardness of the contact surface is set to the hardness of the base material subjected to the surface treatment according to a predetermined condition. Or the vibration actuator of 2. Comprising a lubricant supply means capable of supplying a liquid lubricant between the moving element and the vibrator;
The vibration actuator according to any one of claims 1 to 3, wherein the lubricant supply body is a supply body that is impregnated with a liquid lubricant and is provided so as to be able to contact at least one of the moving element and the vibrator. .

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