JP5098625B2 - Vibration actuator - Google Patents

Description

  The present invention relates to a vibration actuator, and more particularly to a technique for removing foreign matter adhering to the surface of a rotor.

In recent years, a vibration actuator that drives a rotor using ultrasonic vibration has been proposed and put into practical use. This vibration actuator generates an elliptical motion or traveling wave on the surface of the stator using a piezoelectric element, and presses the rotor against the stator to drive the rotor via the friction force between them. Is.
For example, in Patent Document 1, a substantially spherical rotor is sandwiched between a pair of stators, and both stators are arranged in the same direction by vibrating bodies including first to third piezoelectric element portions stacked on each other. The present applicant has disclosed an actuator that generates a plurality of ultrasonic vibrations and rotationally drives a rotor with multiple degrees of freedom. In this actuator, a pre-pressure in a direction in which the rotor is sandwiched between the pair of stators is applied to the rotor, whereby the rotor is in pressure contact with the pair of stators.

JP 2007-135312 A

However, as described above, since the rotor is brought into pressure contact with the stator and the rotor is driven through the frictional force between the two, the wear powder from the rotor and / or the stator as the rotor is driven. Is known to occur. If the wear powder generated in this way enters the contact portion between the stator and the rotor, there is a risk of reducing the drive accuracy of the rotor, such as torque fluctuation, rotor meandering, etc. Since the wear is accelerated by the presence, the life of the actuator may be shortened.
In addition to the wear powder, if dust or the like adheres to the surface of the rotor from the outside, the same problem as the wear powder occurs.
The present invention has been made to solve such problems, and is a vibration actuator that can drive a rotor with high accuracy and achieve a long life even when foreign matter adheres to the surface of the rotor. The purpose is to provide.

The vibration actuator according to the present invention is a vibration actuator that drives a rotor by generating ultrasonic vibrations in the stator in a state in which the rotor is pressurized to the stator by the preloading unit. The foreign matter removing part is disposed so as to slidably contact with the contact surface and to come into contact with the surface of the rotor . The foreign matter removing part is a groove formed on the contact surface of the preloading part with the rotor, or a preload. It is assumed that it is a brush or wiper built in the part .
The vibration actuator according to the present invention is a vibration actuator that drives a rotor by generating ultrasonic vibrations in the stator in a state where the rotor is pressurized to the stator by the preloading portion. The foreign matter removing part is disposed so as to slidably contact with the contact surface and the rotor surface, and the foreign matter removing part is provided in the preloading part, the contact surface of the preloading part and the rotor Air is supplied to the surface.

  According to the present invention, since the foreign matter removing portion is disposed so as to contact the surface of the rotor, the rotor can be driven accurately even if foreign matter adheres to the surface of the rotor, and the service life is extended. It becomes possible to plan.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
Embodiment 1
FIG. 1 shows the configuration of a vibration actuator according to Embodiment 1 of the present invention. A vibrating body 3 is sandwiched between the base 1 and the stator 2, and the base 1 and the stator 2 are connected to each other via a connecting bolt 4 that is passed through the vibrating body 3. The stator 2 has a recess 5 formed on the side opposite to the surface in contact with the vibrating body 3, and the lower portion of the substantially spherical rotor 6 is accommodated in the recess 5. The vibrating body 3 generates ultrasonic vibrations in the stator 2 to rotate the rotor 6, and a drive circuit 7 is electrically connected to the vibrating body 3.

Here, for convenience of explanation, the Z-axis extends from the base 1 toward the rotor 6, the X-axis extends in a direction perpendicular to the Z-axis, and the Y-axis extends in a direction perpendicular to the Z-axis and the X-axis. Shall.
A contact surface 8 located on the XY plane is formed at the opening edge of the concave portion 5 of the stator 2. The rotor 6 is rotatably supported in contact with the contact surface 8 of the recess 5.
A support member 9 is disposed on the top of the stator 2. The support member 9 has an annular portion 10 fixed on the upper surface of the stator 2 and an arch portion 11 extending upward from the annular portion 10, and a preload portion 12 is suspended substantially at the center of the arch portion 11. ing. The lower surface of the preload portion 12 is in contact with the rotor 6, whereby the rotor 6 is in pressure contact with the contact surface 8 of the stator 2.

As shown in FIG. 2, the contact surface 8 of the stator 2 is divided and disposed at four locations in the circumferential direction, and a groove formed along the XZ surface and a groove formed along the YZ surface. A plurality of grooves 13 made of grooves formed along the XY plane are formed. Here, “the groove formed along the XZ plane”, “the groove formed along the YZ plane”, and “the groove formed along the XY plane” are respectively in the XZ plane, the YZ plane, and A groove extending linearly in the XY plane and a groove extending in a curved line such as an arc shape are included.
As shown in FIG. 3, a plurality of grooves 14 including grooves formed along the XZ plane and grooves formed along the YZ plane are also formed on the lower surface of the preload portion 12 in contact with the rotor 6. Is formed.
These grooves 13 and 14 are for accommodating abrasion powder generated as the rotor 6 is driven.

  As shown in FIG. 1, the vibrating body 3 includes first to third piezoelectric element portions 31 to 33 that are located on the XY plane and overlap each other. By generating ultrasonic vibration, the rotor 6 is rotated around the three axes of X, Y, and Z, respectively.

  Specifically, as shown in FIG. 4, the first piezoelectric element portion 31 includes an electrode plate 31a, a piezoelectric element plate 31b, an electrode plate 31c, a piezoelectric element plate 31d, and an electrode plate 31e each having a disk shape. It has a structure that is sequentially stacked. Similarly, the second piezoelectric element portion 32 has a structure in which an electrode plate 32a, a piezoelectric element plate 32b, an electrode plate 32c, a piezoelectric element plate 32d, and an electrode plate 32e each having a disk shape are sequentially stacked. 3 has a structure in which an electrode plate 33a, a piezoelectric element plate 33b, an electrode plate 33c, a piezoelectric element plate 33d, and an electrode plate 33e each having a disk shape are sequentially stacked. These piezoelectric element portions 31 to 33 are arranged in a state of being insulated from the stator 2 and the base portion 1 through insulating sheets 34 to 37 and from each other.

As shown in FIG. 5, the pair of piezoelectric element plates 31 b and 31 d of the first piezoelectric element portion 31 has portions that are divided into two in the Y-axis direction and have opposite polarities, and each has a Z-axis direction (thickness direction). The piezoelectric element plate 31b and the piezoelectric element plate 31d are disposed so as to be reversed with respect to each other.
The pair of piezoelectric element plates 32b and 32d of the second piezoelectric element portion 32 are polarized so as to be expanded or contracted in the Z-axis direction (thickness direction) as a whole without being divided into two. The element plate 32b and the piezoelectric element plate 32d are arranged inside out.
In the pair of piezoelectric element plates 33b and 33d of the third piezoelectric element portion 33, the portions divided into two in the X-axis direction have opposite polarities, and are opposite to expansion and contraction in the Z-axis direction (thickness direction), respectively. The piezoelectric element plate 33b and the piezoelectric element plate 33d are disposed so as to be reversed with respect to each other.

  An electrode plate 31a and an electrode plate 31e disposed on both surface portions of the first piezoelectric element portion 31, an electrode plate 32a and an electrode plate 32e disposed on both surface portions of the second piezoelectric element portion 32, and a third The electrode plate 33a and the electrode plate 33e disposed on both surface portions of the piezoelectric element portion 33 are electrically grounded. Further, the electrode plate 31 c disposed between the pair of piezoelectric element plates 31 b and 31 d of the first piezoelectric element portion 31 and the pair of piezoelectric element plates 32 b and 32 d of the second piezoelectric element portion 32 are disposed. The electrode plate 32c disposed between the pair of piezoelectric element plates 33b and 33d of the third piezoelectric element portion 33 is electrically connected to the drive circuit 7, respectively.

Next, the operation of the vibration actuator according to the first embodiment will be described.
First, when an AC voltage having a frequency close to the natural frequency of the vibration actuator is applied to the vibrating body 3 to the electrode plate 31c of the first piezoelectric element portion 31, a pair of piezoelectric element plates of the first piezoelectric element portion 31 is applied. The two parts 31b and 31d repeat expansion and contraction alternately in the Z-axis direction, and the stator 2 generates a flexural vibration in the Y-axis direction. Similarly, when an AC voltage is applied to the electrode plate 32c of the second piezoelectric element portion 32, the pair of piezoelectric element plates 32b and 32d of the second piezoelectric element portion 32 repeats expansion and contraction in the Z-axis direction, and the stator 2 generates longitudinal vibration in the Z-axis direction. Further, when an AC voltage is applied to the electrode plate 33c of the third piezoelectric element portion 33, the two divided portions of the pair of piezoelectric element plates 33b and 33d of the third piezoelectric element portion 33 expand and contract in the Z-axis direction. Are alternately repeated to generate a flexural vibration in the X-axis direction in the stator 2.

Therefore, for example, when an AC voltage having a phase shifted by 90 degrees is applied from the drive circuit 7 to both the electrode plate 32c of the second piezoelectric element portion 32 and the electrode plate 33c of the third piezoelectric element portion 33, X An elliptical vibration in the XZ plane is generated on the contact surface 8 of the stator 2 that comes into contact with the rotor 6 by combining the axial flexural vibration and the vertical vibration in the Z-axis direction, and the rotor 6 is moved by frictional force. It rotates in the XZ plane, that is, around the Y axis.
Similarly, when an AC voltage whose phase is shifted by 90 degrees is applied from the drive circuit 7 to both the electrode plate 31c of the first piezoelectric element section 31 and the electrode plate 32c of the second piezoelectric element section 32, respectively, the Y axis In the YZ plane is generated on the contact surface 8 of the stator 2 that comes into contact with the rotor 6 by combining the flexural vibration in the direction and the longitudinal vibration in the Z-axis direction, and the rotor 6 becomes YZ via the frictional force. It rotates in the plane, that is, around the X axis.
Further, when an AC voltage having a phase shifted by 90 degrees is applied from the drive circuit 7 to both the electrode plate 31c of the first piezoelectric element portion 31 and the electrode plate 33c of the third piezoelectric element portion 33, the X-axis direction The flexural vibration in the Y-axis direction and the flexural vibration in the Y-axis direction combine to generate an elliptical vibration in the XY plane on the contact surface 8 of the stator 2 that contacts the rotor 6. Within, ie around the Z axis.
By driving the vibrating body 3 in this way, the rotor 6 rotates around the three axes of X, Y, and Z, respectively.

At this time, since the grooves 13 and 14 are formed in the contact surface 8 of the stator 2 that contacts the rotor 6 and the lower surface of the preloading portion 12, respectively, the rotor 6 and the stator are rotated along with the rotation of the rotor 6. Even if wear powder is generated from at least one of 2 and the preloading portion 12, the wear powder adheres to the surface of the rotor 6 and moves along with the rotation of the rotor 6, and the groove 13 on the contact surface 8 of the stator 2. Or it will be accommodated in the groove 14 on the lower surface of the preload portion 12. Further, a part of the abrasion powder adheres to the surface of the rotor 6 and then falls to the upper surface of the stator 2 or the recess 5.
Even if dust or the like other than wear powder adheres to the surface of the rotor 6 from the outside and enters between the contact surface 8 of the stator 2 or the lower surface of the preloading portion 12, dust or the like remains in the groove 13 or the same as the wear powder. It is accommodated in the groove 14.
Therefore, even if foreign matter such as abrasion powder or dust adheres to the surface of the rotor 6, the rotor 6 can be driven with high accuracy without causing torque fluctuation, meandering of the rotor 6 and the like due to the foreign matter. As a result, it is possible to extend the life by suppressing acceleration of wear caused by foreign matter.

  As described above, the plurality of grooves 13 on the contact surface 8 of the stator 2 and the plurality of grooves 14 on the lower surface of the preload portion 12 are formed along the grooves formed along the XZ plane and the YZ plane, respectively. Groove. For this reason, when the rotor 6 rotates around the Y axis (in the XZ plane), a groove corresponding to the driving direction of the rotor 6 among these grooves 13 and 14, that is, a groove formed along the XZ plane. Even if the preload of the stator 2 by the preload portion 12 is non-uniform due to the tolerance of the spherical surface of the rotor 6 and the contact surface 8 of the stator 2, etc. 6 is less likely to be displaced in the rotation direction of the rotor 6, and the rotor 6 rotates stably around the Y axis. Similarly, when the rotor 6 rotates about the X axis (in the YZ plane), the groove 13 and 14 correspond to the direction corresponding to the driving direction of the rotor 6, that is, along the groove formed along the YZ plane. Thus, the rotor 6 moves, and the rotor 6 rotates stably around the X axis.

As shown in FIG. 6, when it is desired to rotate the rotor 6 in an oblique direction with respect to the X-axis direction and the Y-axis direction, rotational movements Y1, Y2, Y3. The rotational movements X1, X2, X3... Around the axis are sequentially and independently performed, and the rotation in the oblique direction is realized by the combination of the rotational movements about the Y axis and the X axis. In this way, stable rotation is possible even in an oblique direction with respect to the X-axis direction and the Y-axis direction.
Further, since the plurality of grooves 13 on the contact surface 8 of the stator 2 have grooves formed along the XY plane, when the rotor 6 rotates around the Z axis (within the XY plane) The rotor 6 moves along a direction corresponding to the driving direction of the rotor 6, that is, along a groove formed along the XY plane, and the rotor 6 rotates stably around the Z axis.

  Moreover, since the friction coefficient between the rotor 6 and the stator 2 is increased by forming the groove 13 on the contact surface 8 of the stator 2, high torque rotation is realized.

Embodiment 2
FIG. 7 shows the configuration of the vibration actuator according to Embodiment 2 of the present invention. This vibration actuator is different from the vibration actuator according to the first embodiment shown in FIG. 1 in that the contact surface of the stator 2 is formed instead of forming the grooves 13 and 14 on the contact surface 8 of the stator 2 and the lower surface of the preloading portion 12, respectively. Brushes 15 and 16 are disposed in the peripheral portion 8 and the recess 5, respectively, and a brush 17 is built in the preloading portion 12, and these brushes 15 to 17 are brought into contact with the surface of the rotor 6.
When the brushes 15 to 17 are brought into contact with the surface of the rotor 6, even if foreign matter such as abrasion powder or dust adheres to the surface of the rotor 6, the foreign matter is brushed by the brushes 15 to 17 as the rotor 6 rotates. Removed. For this reason, it becomes possible to drive the rotor 6 with high accuracy, and it is possible to extend the life by suppressing acceleration of wear due to foreign matter.

In particular, since the brushes 15 and 16 fixed to the stator 2 vibrate together with the stator 2 by the vibrating body 3, the effect of removing foreign matters attached to the surface of the rotor 6 is improved.
Note that, as in the first embodiment, the brushes 15 to 17 described above may be disposed in a vibration actuator in which grooves 13 and 14 are formed in the contact surface 8 of the stator 2 and the lower surface of the preload portion 12, respectively.
Moreover, you may scrape off the foreign material adhering to the surface of the rotor 6 using a wiper instead of the brushes 15-17.

Embodiment 3
FIG. 8 shows the configuration of the vibration actuator according to Embodiment 3 of the present invention. In the vibration actuator according to the first embodiment shown in FIG. 1, air is supplied to the preload portion 12 instead of forming grooves 13 and 14 on the contact surface 8 of the stator 2 and the lower surface of the preload portion 12, respectively. The pipe 18 is connected, and air is ejected between the lower surface of the preload portion 12 and the surface of the rotor 6.
Although the lower surface of the preloading portion 12 is pressurized by the rotor 6, when the rotor 6 is driven, vibration is applied to the rotor 6, so that a slight amount is provided between the lower surface of the preloading portion 12 and the surface of the rotor 6. A large gap is generated, and air from the air supply pipe 18 is ejected along the surface of the rotor 6. The foreign matter adhering to the surface of the rotor 6 can be removed by this ejection of air.

Further, instead of ejecting air from the air supply pipe 18 connected to the preloading portion 12, as shown in FIG. 9, an air suction pipe 19 is connected to the concave portion 5 of the stator 2, and the air in the concave portion 5 is discharged. You may comprise so that it may attract. By sucking the air in the recess 5, the foreign matter adhering to the surface of the rotor 6 around the contact surface 8 of the stator 2 and the foreign matter falling into the recess 5 can be removed.
Using both the air supply pipe 18 connected to the preloading part 12 and the air suction pipe 19 connected to the concave part 5 of the stator 2, air is supplied from between the lower surface of the preloading part 12 and the surface of the rotor 6. The air in the recessed part 5 can also be suck | inhaled, ejecting.

  Further, as in the first embodiment, the vibration actuator in which grooves 13 and 14 are formed in the contact surface 8 of the stator 2 and the lower surface of the preloading portion 12, respectively, or the surface of the rotor 6 as in the second embodiment. The air supply pipe 18 and / or the air suction pipe 19 may be applied to the vibration actuator provided with the brushes 15 to 17 that come into contact with the air.

  In the first to third embodiments described above, the contact surface 8 of the stator 2 is divided and arranged at four locations in the circumferential direction. However, the present invention is not limited to this, and the rotor 6 has an entire circumference. It can also be an annular contact surface that makes contact over the entire surface.

It is sectional drawing which shows the structure of the vibration actuator which concerns on Embodiment 1 of this invention. FIG. 3 is a plan view showing a stator used in the first embodiment. 4 is a bottom view showing a preload portion used in Embodiment 1. FIG. 3 is a partial cross-sectional view illustrating a configuration of a vibrating body used in Embodiment 1. FIG. 3 is a perspective view showing polarization directions of three pairs of piezoelectric element plates of a vibrating body used in Embodiment 1. FIG. FIG. 5 is a diagram illustrating a movement when the rotor is rotated in an oblique direction with respect to the X axis and the Y axis in the first embodiment. 6 is a cross-sectional view illustrating a configuration of a vibration actuator according to Embodiment 2. FIG. FIG. 6 is a cross-sectional view illustrating a configuration of a vibration actuator according to a third embodiment. FIG. 10 is a cross-sectional view illustrating a configuration of a vibration actuator according to a modification of the third embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Base block, 2 Stator, 3 Vibration body, 4 Connection bolt, 5 Recessed part, 6 Rotor, 7 Drive circuit, 8 Contact surface, 9 Support member, 10 Annular part, 11 Arch part, 12 Preload part, 13, 14 Groove, 15-17 brush, 18 air supply pipe, 19 air suction pipe.

Claims (2)

In a vibration actuator that drives the rotor by generating ultrasonic vibration in the stator in a state in which the rotor is pressurized to the stator by a preloading unit,
The preload portion slidably contacts with the rotor on a contact surface,
A foreign matter removing portion is disposed so as to contact the surface of the rotor ,
The vibration actuator, wherein the foreign matter removing portion is a groove formed on the contact surface of the preload portion with the rotor, or a brush or wiper built in the preload portion . In a vibration actuator that drives the rotor by generating ultrasonic vibration in the stator in a state in which the rotor is pressurized to the stator by a preloading unit,
The preload portion slidably contacts with the rotor on a contact surface,
A foreign matter removing portion is disposed so as to contact the surface of the rotor,
  The foreign matter removing section is provided in the preload section, and supplies air between the contact surface of the preload section and the surface of the rotor.

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