JP2009219281A - Piezoelectric actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric actuator which can be linearly driven and rotationally driven simultaneously. <P>SOLUTION: A shaft 13 is attached so as to freely linearly reciprocate and rotate on a through-hole 12 of an axial direction of a stator 11. Piezoelectric ceramics 14, 23 are provided on each of the outer peripheral surface of the stator 11 so as to be deviated from each other on the axial direction. Two electrodes 15, 16 electrically separated in the axial direction are formed on each of the piezoelectric ceramics 14, and electrodes 24-27 are formed on the piezoelectric ceramics 23 provided so as to be deviated from each other in the rotating direction. AC voltages having different phases are simultaneously applied to the electrodes 15, 16 and the electrodes 24-27, thereby simultaneously forming the elliptic movement in the axial direction and the elliptic movement in the rotational direction in the inner periphery of the through-hole 12 and the shaft 13 rotationally driven simultaneously with linear movement. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a piezoelectric actuator that drives a shaft in a straight line and simultaneously rotates.

  A rotary ultrasonic motor is used to rotationally drive the driven member, and a linear ultrasonic motor is used to drive the driven member linearly. These actuators drive the driven member by converting the elastic vibration of the vibrating body into the motion of the driven member by a frictional force. The vibrating body is formed of an elastic body such as a metal and a piezoelectric element bonded thereto, and the ultrasonic motor is also referred to as a piezoelectric actuator.

  As a rotary-type piezoelectric actuator, Patent Document 1 discloses an ultrasonic motor having a disk-shaped stator having a vibrating body provided on the outer peripheral portion and a rotating shaft provided with a rotor that contacts the vibrating body. ing. As a linear type piezoelectric actuator, Patent Document 2 describes a linear motor in which a linear belt-like elastic body provided with a plurality of protrusions is vibrated by a piezoelectric vibrator and a moving body arranged on the protrusions is driven linearly. ing.

For an ultrasonic motor, a standing wave method in which an AC voltage is applied to a piezoelectric element and the driven member is driven by its elastic vibration, and an AC voltage having a predetermined phase difference is applied to a pair of piezoelectric elements. There is a traveling wave system in which a driven member is driven by a traveling wave generated by elastic vibration. In the traveling wave type ultrasonic motor, the driven member is driven in a direction opposite to the traveling direction of the traveling wave by frictional driving by the elliptical motion of the surface of the driven member.
JP-A-2-159984 JP 2001-21670 A

  Traveling wave type ultrasonic motors frictionally drive a moving body by the elliptical motion of the surface of a vibrating body as the traveling wave progresses, and a rotary piezoelectric actuator is used to efficiently apply this frictional force to the moving body. In Patent Document 1, a spring member such as a disc spring is assembled between the rotating shaft and the rotor as described in Patent Document 1. Also in the linear type piezoelectric actuator, a pressing force is applied to the belt-like elastic body by a spring member or the like to the moving body that is linearly driven.

  Piezoelectric actuators have the advantage that they can be reduced in size compared to electromagnetic or fluid actuators because they convert the elastic vibration of the vibrating body into rotational or linear motion of the driven member by friction. It has been put to practical use in camera autofocus mechanisms and surgical microscopes. However, in order to apply a frictional force between the vibrating body and the driven member, it is necessary to incorporate a spring member into the piezoelectric actuator, and there is a limit to downsizing the piezoelectric actuator. In addition, the piezoelectric actuators are different in the structure of the vibrating body between the rotary type and the linear type, so the basic structures are completely different from each other. The driven member cannot be rotated while being driven straight.

  In order to reduce the size of the piezoelectric actuator and to achieve both linear drive and rotational drive with a single piezoelectric actuator, an outer periphery that forms a through hole in a cube-shaped stator and frictionally engages the inner peripheral surface of the through hole. There has been proposed a piezoelectric actuator in which a shaft-like driven member having a surface is provided and piezoelectric elements polarized in the thickness direction are attached to four outer peripheral surfaces surrounding the through hole of the stator.

  In this piezoelectric actuator, when sinusoidal AC voltages whose phases are different from each other by 90 ° are applied to the four piezoelectric elements provided in the circumferential direction, the piezoelectric elements rotate to the inner circumferential surface of the through hole of the stator by expansion and contraction in the width direction. An elliptical motion in the direction is generated, and the driven member is driven to rotate about its axis. Further, when two electrodes separated in the axial direction are provided on each of the piezoelectric elements and a sinusoidal AC voltage having a phase difference of 90 ° is applied to the two electrodes, the stator penetrates due to the expansion and contraction of each piezoelectric element in the axial direction. An elliptical motion in the axial direction is generated on the inner peripheral surface of the hole, and the driven member is linearly driven in the axial direction.

  However, in the above piezoelectric actuator, it is possible to perform both the rectilinear drive and the rotational drive with one piezoelectric actuator, but the rectilinear drive and the rotational drive cannot be performed at the same time. The appearance of a piezoelectric actuator capable of simultaneously performing the above has been desired.

  An object of the present invention is to provide a piezoelectric actuator capable of simultaneously performing linear drive and rotational drive.

  The piezoelectric actuator according to the present invention is a piezoelectric actuator that drives the shaft linearly in the axial direction and at the same time rotationally drives the shaft center, and has a through hole having an inner peripheral surface frictionally engaged with the outer peripheral surface of the shaft. A stator on which the shaft is linearly reciprocable and rotatable; a first piezoelectric element provided on an outer peripheral surface of the stator; and the first piezoelectric element that is electrically separated in an axial direction of the shaft. At least two electrodes for applying alternating voltages of different phases to the element, at least two second piezoelectric elements respectively provided on the outer peripheral surface of the stator so as to be shifted from each other in the rotational direction of the shaft, and the second And an electrode for applying an AC voltage having a different phase to each of the second piezoelectric elements.

  The piezoelectric actuator according to the present invention is a piezoelectric actuator that drives the shaft linearly in the axial direction and at the same time rotationally drives the shaft center, and has a through hole having an inner peripheral surface frictionally engaged with the outer peripheral surface of the shaft. A stator in which the shaft is linearly reciprocable and rotatable, at least two first piezoelectric elements provided in an axial direction of the shaft on an outer peripheral surface of the stator, and each of the first piezoelectric elements. An electrode for applying an alternating voltage having a different phase to each of the first piezoelectric elements, and at least two second piezoelectric elements provided on the outer peripheral surface of the stator while being shifted from each other in the rotation direction of the shaft. And an electrode provided on each of the second piezoelectric elements and for applying an AC voltage having a different phase to each of the second piezoelectric elements. To.

  The piezoelectric actuator of the present invention is characterized in that the first piezoelectric element and the second piezoelectric element are provided in the stator while being mutually shifted in the axial direction of the shaft. The piezoelectric actuator of the present invention is characterized in that the first piezoelectric element and the second piezoelectric element are provided in the stator while being shifted from each other in the rotation direction of the shaft. In the piezoelectric actuator of the present invention, the first piezoelectric element is provided on the stator so as to face each other about the shaft, and the second piezoelectric element is provided on the stator so as to face each other around the shaft. It is characterized by providing.

  In the piezoelectric actuator of the present invention, the electrodes provided in the second piezoelectric elements are separated in the axial direction of the shaft, and an alternating voltage having the same phase is applied to the separated pair of electrodes. It is characterized by.

  The piezoelectric actuator according to the present invention is a piezoelectric actuator that drives the shaft linearly in the axial direction and at the same time rotationally drives the shaft center, and has a through hole having an inner peripheral surface frictionally engaged with the outer peripheral surface of the shaft. A stator on which the shaft is linearly reciprocable and rotatable, a piezoelectric element provided on the outer peripheral surface of the stator, and an alternating current that is electrically separated in the axial direction of the shaft and has a phase different from that of the piezoelectric element At least two electrodes for applying a voltage; a cam groove formed on one of the outer peripheral surface of the shaft or the inner peripheral surface of the stator and having a spiral portion; and the outer peripheral surface of the shaft or the stator And a cam projection provided on the other inner peripheral surface and engaged with the cam groove.

  The piezoelectric actuator of the present invention is a piezoelectric actuator that drives the shaft linearly in its axial direction and at the same time rotationally drives its shaft center, and has a through hole having an inner peripheral surface frictionally engaged with the outer peripheral surface of the shaft, A stator on which the shaft is mounted so as to be linearly reciprocable and rotatable; at least two piezoelectric elements provided in an axial direction of the shaft on an outer peripheral surface of the stator; and each piezoelectric element provided to each of the piezoelectric elements. Electrodes for applying alternating voltages having different phases to each other, a cam groove formed on either the outer peripheral surface of the shaft or the inner peripheral surface of the stator, and having a spiral portion, and the outer peripheral surface of the shaft or the And a cam projection provided on the other inner peripheral surface of the stator and engaged with the cam groove.

  The piezoelectric actuator according to the present invention includes a setting unit that is formed on at least one of the shaft and the stator and sets a frictional contact pressure between the outer peripheral surface of the shaft and the inner peripheral surface of the stator.

  In the piezoelectric actuator of the present invention, the setting portion is a slit that extends in the axial direction by being cut into the shaft in the center direction, and sets the frictional contact pressure by elastic deformation of the shaft. In the piezoelectric actuator of the present invention, the setting portion is a slit that extends in the axial direction by being cut into the stator in the center direction, and sets the frictional contact pressure by elastic deformation of the stator.

  The piezoelectric actuator of the present invention is characterized in that a slider made of a wear-resistant material is provided on one of the shaft and the stator.

  An axial elliptical motion is generated on the inner peripheral surface of the stator by the axial expansion and contraction of the first piezoelectric ceramics provided on the outer peripheral surface of the stator. In addition, elliptical motion in the rotational direction is generated on the inner peripheral surface of the stator by expansion and contraction in the width direction orthogonal to the axial direction of the second piezoelectric ceramic provided on the outer peripheral surface of the stator. By simultaneously expanding and contracting the first piezoelectric ceramic and the second piezoelectric ceramic, the shaft can be driven to rotate simultaneously with the straight drive.

  When the elliptical motion in the axial direction occurs on the inner peripheral surface of the stator due to the axial expansion and contraction of the piezoelectric ceramic provided on the outer peripheral surface of the stator, the shaft can be driven straight and the shaft can be driven to rotate via the cam mechanism. it can.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. 1 is a perspective view of a piezoelectric actuator according to an embodiment of the present invention, FIG. 2 (A) is a cross-sectional view taken along line 2A-2A in FIG. 1, and FIG. 2 (B) is 2B-2B in FIG. 3 is a sectional view taken along line 3-3 of the stator in FIG. 1, FIG. 4 is a circuit diagram showing a connection state between the piezoelectric actuator shown in FIG. 1 and an AC power source, and FIG. FIG. 2 is a schematic cross-sectional view showing the operating principle of the piezoelectric actuator shown in FIG.

  The piezoelectric actuator 10a is a piezoelectric actuator that can perform linear drive and rotational drive at the same time. As shown in FIGS. 1 and 3, the stator 11 includes two substantially cubic metal stator bodies 11a and 11b. have. In the stator 11, two stator bodies 11a and 11b are connected in an axial direction (lateral direction in FIG. 3) by a connecting member 11c, and the stator bodies 11a and 11b have a through-hole 12 having a circular cross section penetrating in the axial direction. Are formed respectively. A shaft 13 having a circular cross section extending in the axial direction is slidably inserted into the through hole 12. The shaft 13 which is a driven member is frictionally engaged with the inner peripheral surface 12a of the through hole 12 of the stator body 11a and the inner peripheral surface 12b of the through hole 12 of the stator body 11b through a slider which will be described later. The shaft 13 is mounted on the stator 11 so as to be linearly reciprocable and rotatable.

  For example, phosphor bronze is used as the stator 11 in terms of wear resistance and temperature characteristics of vibration, but is not limited thereto. The shaft 13 is made of, for example, stainless steel or aluminum, but is not limited thereto. Of course, the shaft 13 is not limited to a solid shape, and may be a hollow shape. Furthermore, the stator 11 may be formed integrally with the stator bodies 11a and 11b without providing the connecting member 11c.

  On the outer periphery of the stator body 11a, there are four flat portions that are flat in the direction in which the through-hole 12 is formed. As shown in FIG. One piezoelectric ceramic 14 is attached by pasting or the like. The four piezoelectric ceramics 14 and the stator body 11a form a linear motion vibrating body that drives the shaft 13 to advance in the axial direction. The piezoelectric ceramics 14 are provided on the outer peripheral surface of the stator body 11a so as to face each other with the shaft 13 as a center. The direct acting stator body 11a may have a shape having at least one flat surface portion so that at least one piezoelectric ceramic 14 is provided.

  Each piezoelectric ceramic 14 is polarized in the thickness direction. When a voltage in the same direction as the polarization direction is applied, the piezoelectric ceramic 14 contracts in the axial direction of the shaft 13, and when a voltage in the direction opposite to the polarization direction is applied, the axis of the shaft 13 is applied. Stretch in the direction. As the piezoelectric ceramic 14, barium titanate, lead titanium zirconate, or the like is used, but is not limited thereto.

  As shown in FIGS. 1 and 3, the outer surface of the piezoelectric ceramic 14 (surface opposite to the stator body 11a) has two electrodes 15 and 16 that are electrically separated in the axial direction of the shaft 13. The electrodes 15 and 16 provided so as to be shifted from each other in the axial direction are connected to an electric circuit by lead wires (not shown). The two electrodes formed on the outer surface of the linearly acting piezoelectric ceramic 14 constitute a pair of electrodes, and at least two electrodes are required to apply alternating voltages having different phases.

  On the other hand, an electrode 17 is formed on the inner surface (surface on the side of the stator body 11a) of the piezoelectric ceramic 14 so as to correspond to the electrodes 15 and 16, and the piezoelectric ceramic 14 is connected to the outer peripheral surface of the stator body 11a via the electrode 17. Is attached. The electrode 17 is in electrical contact with the stator body 11a. When the stator body 11a is grounded, one side of each piezoelectric ceramic 14 is grounded.

  As shown in FIG. 4, each electrode 15 is connected to an AC power source 18, and each electrode 16 is connected to an AC power source 19. The AC power supplies 18 and 19 constitute a direct-acting power supply unit that applies sinusoidal AC voltages having the same resonance frequency and the same amplitude and different phases by 90 ° to the piezoelectric ceramics 14 via the electrodes 15 and 16. is doing.

  In this way, each piezoelectric ceramic 14 is provided with the two electrodes 15 and 16 that are electrically separated in the axial direction of the shaft 13, so that the first expansion region 20 provided with the first electrode 15 and the first expansion region 20 are provided. It has two expansion / contraction regions in the axial direction with the second expansion / contraction region 21 provided with the two electrodes 16, thereby constituting a linear motion vibration source. By attaching two piezoelectric ceramics to the flat portion of the outer surface of the stator 11 in the axial direction of the shaft 13, two expansion regions are provided in the axial direction so as to constitute a vibration source for linear motion. Also good. Alternatively, the electrode 17 may be formed by two electrodes corresponding to the electrodes 15 and 16, or one side of the piezoelectric ceramic 14 may be directly attached to the outer peripheral surface of the stator body 11 a without providing the electrode 17.

  On the outer periphery of the stator body 11b, there are four flat portions flattened in the direction in which the through holes 12 are formed. As shown in FIG. Two piezoelectric ceramics 23 are attached by pasting or the like. The four piezoelectric ceramics 23 and the stator body 11b form a rotating vibration body that rotates the shaft 13 about its axis. At least two piezoelectric ceramics 23 for rotation need to be provided in the rotation direction of the shaft 13, and the stator body 11 b for rotation needs to have a shape having at least two plane portions provided so as to be shifted from each other in the rotation direction. is there. Further, in consideration of driving stability and the like, it is preferable to provide three or more, particularly four piezoelectric ceramics 23 for rotation in the rotation direction of the shaft 13, and the stator body 11b for rotation is shifted from each other in the rotation direction. It is preferable that the shape has at least three, preferably four, flat portions provided.

  The piezoelectric ceramics 23 are provided on the outer peripheral surface of the stator body 11b so as to face each other with the shaft 13 as a center and are shifted from each other in the rotation direction of the shaft 13. Each piezoelectric ceramic 23 is polarized in the thickness direction. When a voltage in the same direction as the polarization direction is applied, the piezoelectric ceramic 23 contracts in the width direction orthogonal to the shaft 13, and when a voltage in the direction opposite to the polarization direction is applied, the shaft 13 Stretch in the orthogonal width direction.

  As shown in FIG. 2A, electrodes 24 to 27 are formed on the outer surfaces (surfaces opposite to the stator body 11b) of the four piezoelectric ceramics 23, and these are formed in an electric circuit by lead wires (not shown). It is connected. On the other hand, an electrode 17 is formed on the inner surface of the piezoelectric ceramic 23 (the surface on the side of the stator body 11 b) corresponding to the electrodes 24 to 27, and the piezoelectric ceramic 23 is disposed on the outer peripheral surface of the stator body 11 b via the electrode 17. It is attached. The electrode 17 is in electrical contact with the stator body 11b. When the stator body 11b is grounded, one side of each piezoelectric ceramic 23 is grounded.

  As shown in FIG. 4, the electrodes 24-27 are connected to AC power supplies 28-31, respectively. The AC power supplies 28 to 31 are rotating power supply units that apply sinusoidal AC voltages having the same resonance frequency and the same amplitude and different phases by 90 ° to the piezoelectric ceramics 23 via the electrodes 24 to 27. It is composed.

  As described above, the four piezoelectric ceramics 23 are arranged separately in the rotation direction, and thereby, the first stretchable region 32 provided with the first electrode 24 and the second electrode 25 provided with the second electrode 25 are provided. 2 stretchable regions 33, a third stretchable region 34 provided with the third electrode 26, and a fourth stretchable region 35 provided with the fourth electrode 27. ing.

  The AC voltages of the AC power supplies 18 and 19 are sinusoidal and 90 ° out of phase with each other. As shown in FIG. 5, elastic vibrations due to expansion and contraction are generated in the expansion and contraction regions 20 and 21, respectively. FIGS. 5A to 5D show states of this elastic vibration every quarter period. When a voltage in a direction opposite to the polarization direction of the piezoelectric ceramic 14 is applied to the electrodes 15 and 16, the stretchable region 20. , 21 are stretched to the state shown in FIG. 5A, and when the voltage in the same direction as the polarization direction is applied to the electrode 15 and the voltage in the direction opposite to the polarization direction is applied to the electrode 16, the stretchable region 20 contracts. However, the stretchable region 21 is stretched to the state shown in FIG. Further, when a voltage in the same direction as the polarization direction of the piezoelectric ceramic 14 is applied to the electrodes 15 and 16, the stretchable regions 20 and 21 are both contracted to the state shown in FIG. 5C, and the electrode 15 is opposite to the polarization direction. When a voltage in the direction is applied and a voltage in the same direction as the polarization direction is applied to the electrode 16, the stretchable region 20 is stretched, but the stretchable region 21 is contracted to a state shown in FIG.

  By applying a sinusoidal AC voltage having a phase difference of 90 ° to the electrodes 15 and 16, the states shown in FIGS. 5A to 5D change continuously as described above, and an AC voltage is applied. While continuing, elastic vibration due to expansion and contraction is repeated. As shown in FIGS. 5A to 5D, the piezoelectric ceramic 14 expands and contracts in the axial direction of the shaft 13 on the inner peripheral surface 12 a of the through-hole 12. A wavefront of a traveling wave traveling in the left direction is formed.

  When the traveling wave formed on the inner peripheral surface 12a travels, the contact portion between the outer peripheral surface of the shaft 13 and the inner peripheral surface 12a of the stator body 11a changes continuously in the traveling direction. If this change is seen about any one point of the inner peripheral surface 12a of the through-hole 12, the elliptical motion is carried out counterclockwise in a figure with progress of a traveling wave. As shown in FIG. 5C, the inner peripheral surface 12a of the stator body 11a and the outer peripheral surface of the slider provided on the shaft 13 come into contact with each other at the apex of the elliptical motion, and the frictional force is opposite to the traveling direction of the traveling wave. As a result, the shaft 13 is friction-driven in the right direction in FIG. 5 which is opposite to the traveling direction of the traveling wave.

  Further, the AC voltages of the AC power supplies 28 to 31 are 90 ° out of phase with each other, and elastic vibrations are generated in the expansion and contraction regions 32 to 35 provided in the stator body 11 b by being shifted in the rotation direction of the shaft 13. I am letting. As the four piezoelectric ceramics 23 expand and contract in the width direction perpendicular to the shaft 13 on the inner peripheral surface 12b of the through hole 12 of the stator body 11b, the rotation proceeds in the counterclockwise direction of rotation in FIG. A wavefront of the traveling wave is formed. That is, a wavefront of a traveling wave of elastic vibration is formed on the inner peripheral surface 12b by elastic vibration of each of the expansion / contraction regions 32 to 35 on the inner peripheral surface 12b. Due to the progress of the traveling wave, an elliptical motion is generated in the rotational direction on the inner peripheral surface 12b of the stator body 11b. By this elliptical motion, the shaft 13 having the slider frictionally engaged with the inner peripheral surface 12b of the stator body 11b is frictionally driven in the direction opposite to the traveling direction of the traveling wave.

  In this way, by applying a sinusoidal AC voltage having a phase difference of 90 ° to the electrodes 15 and 16 formed in the axial direction on the piezoelectric ceramics 14 provided on the outer peripheral surface of the stator body 11a, A wavefront of the traveling wave in the axial direction is formed on the inner peripheral surface 12 a of the through hole 12, and an elliptical motion in the axial direction is generated on the inner peripheral surface 12 a of the through hole 12. By this elliptical motion, the shaft 13 frictionally engaged with the inner peripheral surface 12a is frictionally driven in the direction opposite to the traveling direction of the traveling wave.

  Further, a sinusoidal AC voltage having a phase difference of 90 ° is applied to the electrodes 24 to 27 formed on the piezoelectric ceramics 23 provided on the outer peripheral surface of the stator body 11b so as to be shifted from each other in the rotation direction. On the inner peripheral surface 12b of the hole 12, an elliptical motion in the rotational direction occurs. By this elliptical motion, the shaft 13 frictionally engaged with the inner peripheral surface 12b is frictionally driven in the direction opposite to the traveling direction of the traveling wave.

  As shown in FIG. 4, when the linear motion power supplies 18 and 19 and the rotation power supplies 28 to 31 are simultaneously connected to the piezoelectric actuator 10a, the elliptical motion in the axial direction is caused on the inner peripheral surface 12a of the through hole 12 of the stator body 11a. In addition, elliptical motion in the rotational direction occurs on the inner peripheral surface 12b of the through hole 12 of the stator body 11b. For this reason, the shaft 13 is linearly driven in the axial direction by these two elliptical motions, and at the same time is rotationally driven about the axis. Therefore, the single piezoelectric actuator 10a can drive the shaft 13 straightly in the axial direction and simultaneously rotate the shaft 13 about the axis.

  Further, by reversing the direction of the elliptical motion formed on the inner peripheral surface 12a and the direction of the elliptical motion formed on the inner peripheral surface 12b, the linear drive direction and the rotational drive direction of the shaft 13 can be changed. it can. Only the linear motion power sources 18 and 19 are connected to the piezoelectric actuator 10a to drive the shaft 13 straight without rotating, or only the rotational power sources 28 to 31 are connected to the piezoelectric actuator 10a to drive the shaft 13 linearly. Alternatively, it may be rotated without being driven.

  As shown in FIGS. 1 and 2, a slider 37 made of an abrasion-resistant material is provided on the outer peripheral surface of the shaft 13, and the shaft 13 is formed on the inner peripheral surfaces 12 a and 12 b of the through hole 12 via the slider 37. Friction is engaged. Since the slider 37 reduces wear on the inner peripheral surfaces 12a and 12b of the through-hole 12 and the outer peripheral surface of the shaft 13, it is possible to prevent a decrease in driving efficiency of the piezoelectric actuator 10a and to drive the shaft 13 at the time of driving. Soundproof effect can be obtained.

  The shaft 13 and the slider 37 are formed with slits 38 that are cut in the central direction and extend in the axial direction. The slits 38 are formed through the slider 37 and the inner peripheral surfaces 12 a and 12 b of the stator 11. It is a setting part which sets the friction contact pressure. By forming the slits 38 in the shaft 13 and the slider 37, the shaft 13 can be elastically deformed in the direction of narrowing the interval between the slits 38, and the shaft 13 is interposed via the slider 37 by the elastic restoring force of the shaft 13. Appropriate frictional contact pressure can be applied between the outer peripheral surface of the stator and the inner peripheral surfaces 12a, 12b of the stator 11. Therefore, a frictional force can be generated between the outer peripheral surface of the shaft 13 and the inner peripheral surfaces 12a and 12b of the stator 11 via the slider 37, and the driving efficiency of the piezoelectric actuator 10a can be improved. In addition, since the frictional contact pressure can be generated by the shaft 13 itself, it is not necessary to provide a spring member or the like for applying the frictional contact pressure, and the piezoelectric actuator 10a can be downsized.

  Further, since the outer peripheral surface of the shaft 13 is pressed against the inner peripheral surfaces 12a and 12b of the stator 11 by frictional contact pressure, the outer peripheral surface of the slider 37 and the inner peripheral surfaces 12a and 12b of the stator 11 are worn by use. Also, a decrease in drive efficiency can be prevented. Furthermore, if the shaft 13 is set so as to be strongly pressed against the inner peripheral surfaces 12a and 12b of the stator 11 by adjusting the frictional contact pressure, it has a holding force to hold the shaft 13 on the stator 11 even when stopped. Therefore, it becomes possible to prevent the linear movement and rotation of the shaft 13 at the time of stopping.

  Stoppers 39 projecting in the lateral direction are attached to the outer peripheral surfaces of both axial ends of the shaft 13, and the maximum displacement amount of the axial displacement of the shaft 13 is defined, and the shaft 13 is prevented from coming off from the stator 11. It is preventing. The stopper 39 is not necessarily attached to the shaft 13, and may be attached to the outside of the stator 11 or the piezoelectric actuator 10a.

  Further, in this type of piezoelectric actuator, the expansion and contraction of the vibrating body that forms the traveling wave is on the order of microns, and the displacement amount in one cycle is extremely small. In order to prevent this vibration from propagating to other devices and a decrease in driving efficiency due to the vibration, the stator 11 is fixed via a vibration isolating support base 40. Note that the shaft 13 may be fixed via the anti-vibration support base 40.

  In the present embodiment, two electrodes 15 and 16 that are electrically separated are formed on the piezoelectric ceramic 14, and an AC voltage having a phase difference of 90 ° is applied to the electrodes 15 and 16, so that the inner circumference of the through-hole 12 Although the shaft 13 is driven linearly by generating an elliptical motion in the axial direction on the surface 12a, two piezoelectric ceramics are attached to the outer peripheral surface of the stator 11 in the axial direction of the shaft 13, and the phase is applied to the two piezoelectric ceramics. Alternatively, an AC voltage that is 90 ° different from each other may be applied to generate an elliptical motion in the axial direction on the inner peripheral surface 12a of the through hole 12 to drive the shaft 13 straightly.

  6 is a perspective view of a piezoelectric actuator according to another embodiment of the present invention, FIG. 7 is a sectional view taken along line 7-7 in FIG. 6, and FIG. 8 is a connection between the piezoelectric actuator shown in FIG. It is a circuit diagram which shows a state. In these drawings, members common to the above-described piezoelectric actuator are given the same reference numerals.

  The piezoelectric actuator 10b is a piezoelectric actuator that can perform linear drive and rotational drive simultaneously, and includes a metal stator 11 having a regular octagonal cross section as shown in FIGS. The stator 11 is formed with a through hole 12 having a circular cross section penetrating in the axial direction, and a shaft 13 having a circular cross section extending in the axial direction is slidably inserted into the through hole 12. The shaft 13 as a driven member is frictionally engaged with the inner peripheral surface 12a of the through hole 12 via a slider 37 provided on the outer peripheral surface, and the shaft 13 is mounted on the stator 11 so as to be linearly reciprocable and rotatable. Has been.

  The outer periphery of the stator 11 has eight flat portions flattened in the direction in which the through holes 12 are formed. As shown in FIG. 7, the first piezoelectric ceramics 14 serving as a vibration source are provided on the respective flat portions. And the second piezoelectric ceramics 23 are provided alternately in the circumferential direction, and the four piezoelectric ceramics 14, the four piezoelectric ceramics 23, and the stator 11 form a vibrating body. The piezoelectric ceramics 14 and 23 are provided on the outer peripheral surface of the stator 11 so as to face each other with the shaft 13 as a center and are shifted from each other in the rotation direction of the shaft 13.

  In the present embodiment, four piezoelectric ceramics 14 and four piezoelectric ceramics 23 are alternately arranged on the outer peripheral surface of the stator 11 having a regular octagonal cross section. However, at least one piezoelectric ceramic 14 is required for linear drive. Further, it is necessary to provide at least two piezoelectric ceramics 23 for rotation in the rotation direction of the shaft 13. Further, considering the driving stability and the like, three piezoelectric ceramics 23 for rotation are provided in the rotation direction of the shaft 13. As described above, it is particularly preferable to provide four. Therefore, it is preferable that the stator 11 has a shape having at least four flat portions provided in the rotational direction as the flat portions for mounting the piezoelectric ceramic 23 for rotation.

  The four piezoelectric ceramics 14 constitute direct-acting piezoelectric ceramics, and have the same structure as the direct-acting piezoelectric ceramics 14 in the piezoelectric actuator 10a. Further, the four piezoelectric ceramics 23 constitute rotating piezoelectric ceramics, and have the same structure as the rotating piezoelectric ceramics in the piezoelectric actuator 10a. Therefore, the description about the piezoelectric ceramics 14 and 23 is omitted.

  As shown in FIG. 8, the power supply unit of the electric circuit connected to the piezoelectric actuator 10b is for direct acting that applies sinusoidal AC voltages whose phases are different from each other by 90 ° to the electrodes 15 and 16 provided on the piezoelectric ceramic 14. Power sources 18 and 19 and power sources 28 to 31 for rotation for applying sinusoidal AC voltages whose phases are different from each other by 90 ° to electrodes 24 to 27 provided on the piezoelectric ceramics 23.

  A sinusoidal AC voltage having a phase difference of 90 ° between electrodes 15 and 16 formed by being electrically separated in the axial direction from piezoelectric ceramics 14 provided on the outer peripheral surface of stator 11 by power sources 18 and 19 for linear motion. Is applied to the inner peripheral surface 12a of the through-hole 12 to form a traveling wave front in the axial direction, and an axial elliptical motion occurs on the inner peripheral surface 12a of the through-hole 12. By this elliptical motion, the shaft 13 frictionally engaged with the inner peripheral surface 12a is frictionally driven in the direction opposite to the traveling direction of the traveling wave.

  Also, sinusoidal AC voltages whose phases are different from each other by 90 ° with respect to the electrodes 24 to 27 formed on the piezoelectric ceramics 23 provided on the outer peripheral surface of the stator 11 so as to be shifted from each other in the rotation direction by the power sources 28 to 31 for rotation. Is applied to the inner peripheral surface 12a of the through-hole 12 to form a traveling wave front in the rotational direction, and the inner peripheral surface 12a of the through-hole 12 generates an elliptical motion in the rotational direction. By this elliptical motion, the shaft 13 frictionally engaged with the inner peripheral surface 12b is frictionally driven in the direction opposite to the traveling direction of the traveling wave.

  As shown in FIG. 8, when the linear motion power supplies 18 and 19 and the rotation power supplies 28 to 31 are connected simultaneously, the elliptical motion in the axial direction and the elliptical motion in the rotational direction are caused on the inner peripheral surface 12a of the through hole 12 of the stator 11. Movement occurs simultaneously. For this reason, the shaft 13 is linearly driven in the axial direction by these two elliptical motions, and at the same time is rotationally driven about the axis. Therefore, the single piezoelectric actuator 10b can drive the shaft 13 straightly in the axial direction and simultaneously rotate the shaft 13 about the axis.

  Further, by reversing the direction of the elliptical motion in the axial direction and the elliptical motion in the rotational direction formed on the inner peripheral surface 12a, the linear drive direction and the rotational drive direction of the shaft 13 can be changed. Only the power sources 18 and 19 for linear motion are connected to drive the shaft 13 straight without rotating, or only the power sources 28 to 31 for rotation are connected to rotate the shaft 13 without driving straight. May be.

  Similar to the piezoelectric actuator 10 a, a slider 37 made of an abrasion resistant material is provided on the outer peripheral surface of the shaft 13, and the shaft 13 is frictionally engaged with the inner peripheral surface 12 a of the through hole 12 via the slider 37. ing. The slider 37 reduces wear of the inner peripheral surface 12a of the through-hole 12 and the outer peripheral surface of the shaft 13, so that it is possible to prevent a decrease in driving efficiency of the piezoelectric actuator 10b and to prevent sound during driving of the shaft 13. An effect is obtained.

  Further, the shaft 13 and the slider 37 are formed with slits 38 that are cut in the central direction and extend in the axial direction, and generate a frictional force between the shaft 13 and the inner peripheral surface 12a of the stator 11 with a simple configuration. Since the driving efficiency of the piezoelectric actuator 10b can be improved and the frictional contact pressure can be generated by the shaft 13 itself, there is no need to provide a spring member or the like for applying the frictional contact pressure. The piezoelectric actuator 10b can be downsized.

  In the present embodiment, two electrodes 15 and 16 that are electrically separated are formed on the piezoelectric ceramic 14, and an AC voltage having a phase difference of 90 ° is applied to the electrodes 15 and 16, so that the inner circumference of the through-hole 12 Although the shaft 13 is driven linearly by generating an elliptical motion in the axial direction on the surface 12a, two piezoelectric ceramics are attached to the outer peripheral surface of the stator 11 in the axial direction of the shaft 13, and the phase is applied to the two piezoelectric ceramics. Alternatively, an AC voltage that is 90 ° different from each other may be applied to generate an elliptical motion in the axial direction on the inner peripheral surface 12a of the through hole 12 to drive the shaft 13 straightly.

  9 is a perspective view of a piezoelectric actuator according to another embodiment of the present invention, FIG. 10A is a cross-sectional view taken along line 10A-10A in FIG. 9, and FIG. 10B is 10B-10B in FIG. FIG. 11 is a circuit diagram showing a connection state between the piezoelectric actuator shown in FIG. 9 and an AC power supply. In these drawings, members common to the above-described piezoelectric actuator are given the same reference numerals.

  The piezoelectric actuator 10c is a piezoelectric actuator that can perform linear drive and rotational drive simultaneously, and has a substantially cubic metal stator 11 as shown in FIG. The stator 11 is formed with a through hole 12 having a circular cross section penetrating in the axial direction, and a shaft 13 having a circular cross section extending in the axial direction is slidably inserted into the through hole 12. The shaft 13 as a driven member is frictionally engaged with the inner peripheral surface 12a of the through hole 12 via a slider 37 provided on the outer peripheral surface, and the shaft 13 is mounted on the stator 11 so as to be linearly reciprocable and rotatable. Has been.

  As shown in FIG. 10, the outer periphery of the stator 11 has four flat portions flattened in the direction in which the through holes 12 are formed. One piezoelectric ceramic 14 and three second piezoelectric ceramics 23 for rotational driving are provided, and the piezoelectric ceramics 14 and 23 and the stator 11 form a vibrating body. The piezoelectric ceramics 14 and 23 are provided on the outer peripheral surface of the stator 11 so as to face each other with the shaft 13 as a center and are shifted from each other in the rotation direction of the shaft 13.

  In the present embodiment, one piezoelectric ceramic 14 and three piezoelectric ceramics 23 are provided, but at least one piezoelectric ceramic 14 is required for linear drive. In addition, it is necessary to provide at least two piezoelectric ceramics 23 for rotation in the rotation direction of the shaft 13. Further, considering the driving stability and the like, three or more piezoelectric ceramics 23 for rotation are provided in the rotation direction of the shaft 13. It is particularly preferable to provide four. Therefore, it is preferable that the stator 11 has a shape having at least four flat portions provided as being shifted in the rotation direction as mounting flat portions of the rotating piezoelectric ceramics 23.

  The first piezoelectric ceramic 14 is polarized in the thickness direction. When a voltage in the same direction as the polarization direction is applied, the first piezoelectric ceramic 14 contracts in the axial direction of the shaft 13, and when a voltage in the direction opposite to the polarization direction is applied, the shaft 13 Stretch in the axial direction. The second piezoelectric ceramics 23 are also polarized in the thickness direction. When a voltage in the same direction as this polarization direction is applied, the second piezoelectric ceramic 23 contracts in the width direction orthogonal to the axial direction of the shaft 13 and voltage in the direction opposite to the polarization direction. Is applied, it extends in the width direction orthogonal to the axial direction of the shaft 13.

  As shown in FIG. 10, two electrodes 15 and 16 that are electrically separated in the axial direction of the shaft 13 are formed on the outer surface of the first piezoelectric ceramic 14 (the surface opposite to the stator 11). In addition, electrodes 24a and 24b, electrodes 25a and 25b, and electrodes 26a, which are electrically separated in the axial direction of the shaft 13 are provided on the outer surfaces (surfaces opposite to the stator 11) of the three piezoelectric ceramics 23, respectively. 26b is formed, and each is connected to an electric circuit by a lead wire (not shown).

  On the other hand, electrodes 17 are formed on the inner surfaces (surfaces on the stator 11 side) of the piezoelectric ceramics 14 and 23, and the inner surfaces of the piezoelectric ceramics 14 and 23 are connected to the outer peripheral surface of the stator 11 via the electrodes 17. It is attached by pasting. The electrode 17 is in electrical contact with the stator 11, and one side of each of the piezoelectric ceramics 14 and 23 is grounded by the stator 11 being grounded.

  As shown in FIG. 11, an AC power source 18 is connected to the electrode 15, and an AC power source 19 is connected to the electrode 16. The AC power sources 18 and 19 are mutually connected at the same resonance frequency and the same amplitude. A linear motion power supply unit is configured to apply sinusoidal AC voltages having phases different by 90 ° to the first piezoelectric ceramics 14 via the electrodes 15 and 16. An AC power supply 28 is connected to the electrodes 24a and 24b, an AC power supply 29 is connected to the electrodes 25a and 25b, an AC power supply 30 is connected to the electrodes 26a and 26b, and the AC power supplies 28 to 30 are Both of them constitute a power supply unit for rotation that applies a sinusoidal AC voltage having the same resonance frequency and the same amplitude and a phase difference of 90 ° to the second piezoelectric ceramic 23.

  A sinusoidal AC voltage having a phase difference of 90 ° is applied to the electrodes 15 and 16 formed on the first piezoelectric ceramic 14 so as to be separated in the axial direction, whereby an axial direction is applied to the inner peripheral surface 12a of the through hole 12. A wavefront of the traveling wave is formed, and an elliptical motion in the axial direction occurs on the inner peripheral surface 12a of the through hole 12. By this elliptical motion, the shaft 13 frictionally engaged with the inner peripheral surface 12a is frictionally driven in the direction opposite to the traveling direction of the traveling wave.

  Further, by applying a sinusoidal AC voltage having a phase difference of 90 ° to the electrodes 24a and 24b, the electrodes 25a and 25b, and the electrodes 26a and 26b formed on the second piezoelectric ceramic 23, the through holes 12 An elliptical motion in the rotational direction occurs on the inner peripheral surface 12a. By this elliptical motion, the shaft 13 frictionally engaged with the inner peripheral surface 12a is frictionally driven in the direction opposite to the traveling direction of the traveling wave.

  As shown in FIG. 11, when the linear motion power supplies 18 and 19 and the rotation power supplies 28 to 30 are simultaneously connected to the piezoelectric actuator 10 c, an elliptical motion in the axial direction occurs on the inner peripheral surface 12 a of the through hole 12 of the stator 11. Oval motion in the direction of rotation occurs. For this reason, the shaft 13 is linearly driven in the axial direction by these two elliptical motions, and at the same time is rotationally driven about the axis. Accordingly, the single piezoelectric actuator 10c can drive the shaft 13 straightly in the axial direction and simultaneously rotate the shaft 13 about the axis.

  Further, by reversing the direction of the elliptical motion in the axial direction and the direction of the elliptical motion formed in the inner peripheral surface 12a, the direction of linear drive and the direction of rotational drive of the shaft 13 can be changed. Further, only the linear motion power sources 18 and 19 are connected to the piezoelectric actuator 10c so that the shaft 13 is driven straight without rotating, or only the rotational power sources 28 to 30 are connected to the piezoelectric actuator 10c. It may be driven to rotate without being driven straight.

  As shown in FIGS. 9 and 10, a slider 37 made of an abrasion-resistant material is provided on the outer peripheral surface of the shaft 13, and the shaft 13 is frictionally engaged with the inner peripheral surface 12 a of the through hole 12 via the slider 37. Are combined. Since the slider 37 reduces wear on the inner peripheral surface 12a of the through hole 12 and the outer peripheral surface of the shaft 13, it is possible to prevent a decrease in driving efficiency of the piezoelectric actuator 10c and to prevent sound during driving of the shaft 13. An effect is obtained.

  A slit 38 is formed in the shaft 13 and the slider 37 so as to be cut in the center direction and extend in the axial direction. The slit 38 is a friction between the outer peripheral surface of the shaft 13 and the inner peripheral surface 12 a of the stator 11 via the slider 37. It is a setting unit that sets the contact pressure. By forming the slits 38 in the shaft 13 and the slider 37, the shaft 13 can be elastically deformed in the direction of narrowing the interval between the slits 38. After the shaft 13 is mounted on the inner peripheral surface 12 a of the stator 11, An appropriate frictional contact pressure can be applied between the outer peripheral surface of the shaft 13 and the inner peripheral surface 12 a of the stator 11 via the slider 37 by the elastic restoring force 13. Therefore, a frictional force can be generated with a simple configuration between the outer peripheral surface of the shaft 13 and the inner peripheral surface 12a of the stator 11 via the slider 37, and the driving efficiency of the piezoelectric actuator 10c can be improved. Since the frictional contact pressure can be generated by the shaft 13 itself, there is no need to provide a spring member or the like for applying the frictional contact pressure, and the piezoelectric actuator 10c can be downsized.

  Further, since the outer peripheral surface of the shaft 13 is pressed against the inner peripheral surface 12a of the stator 11 by the frictional contact pressure, the driving efficiency is improved even when the outer peripheral surface of the slider 37 and the inner peripheral surface 12a of the stator 11 are worn by use. A decrease can be prevented. Furthermore, if the shaft 13 is set so as to be strongly pressed against the inner peripheral surface 12a of the stator 11 by adjusting the frictional contact pressure, the shaft 13 has a holding force to hold the shaft 13 on the stator 11 even when stopped. Therefore, it is also possible to prevent the linear movement and rotation of the shaft 13 when stopped.

  In the present embodiment, two electrodes 15 and 16 that are electrically separated are formed on the piezoelectric ceramic 14, and an AC voltage having a phase difference of 90 ° is applied to the electrodes 15 and 16, so that the inner circumference of the through-hole 12 Although the shaft 13 is driven linearly by generating an elliptical motion in the axial direction on the surface 12a, two piezoelectric ceramics are attached to the outer peripheral surface of the stator 11 in the axial direction of the shaft 13, and the phase is applied to the two piezoelectric ceramics. Alternatively, an AC voltage that is 90 ° different from each other may be applied to generate an elliptical motion in the axial direction on the inner peripheral surface 12a of the through hole 12 to drive the shaft 13 straightly. In addition, the first piezoelectric ceramic 14 and the second piezoelectric ceramic 23 are provided on the stator 11 while being shifted in the rotational direction of the shaft 13, but as shown in FIG. You may make it provide in.

  12 is a perspective view of a piezoelectric actuator according to another embodiment of the present invention, FIG. 13 is a sectional view taken along line 13-13 in FIG. 12, and FIG. 14 is a sectional view taken along line 14-14 in FIG. FIG. 15 is a circuit diagram showing a connection state between the piezoelectric actuator shown in FIG. 12 and an AC power supply. In these drawings, members common to the above-described piezoelectric actuator are given the same reference numerals.

  The piezoelectric actuator 10d is a piezoelectric actuator that can perform linear drive and rotational drive simultaneously. As shown in FIG. 12, the substantially cubic metal stator 11 has a circular cross section that penetrates in the axial direction. A through hole 12 is formed. A shaft 13 having a circular cross section extending in the axial direction is slidably inserted into the through hole 12. The outer peripheral surface of the shaft 13 which is a driven member is frictionally engaged with the inner peripheral surface 12a of the through hole 12, and the shaft 13 is mounted on the stator 11 so as to be linearly reciprocable and rotatable.

  The stator 11 is a linear motion stator, and has the same structure as the stator body 11a of the piezoelectric actuator 10a. Therefore, the description about the stator 11 is omitted.

  As shown in FIGS. 12 and 14, a spiral cam groove 42 is formed on the outer peripheral surface of the shaft 13, and a cam projection 43 that engages with the cam groove 42 is provided on the stator 11. The cam protrusion 43 is slidable in the cam groove 42. The cam groove 42 may be formed on the inner peripheral surface 12 a of the stator 11, or the cam protrusion 43 may be provided outside the shaft 13 or the actuator 13.

  As shown in FIG. 15, each electrode 15 is connected to an AC power source 18, and each electrode 16 is connected to an AC power source 19. The AC power supplies 18 and 19 constitute a direct-acting power supply unit that applies sinusoidal AC voltages having the same resonance frequency and the same amplitude and different phases by 90 ° to the piezoelectric ceramics 14 via the electrodes 15 and 16. is doing. When AC power supplies 18 and 19 are connected to the piezoelectric actuator 10d, the two electrodes 15 and 16 formed by being electrically separated in the axial direction of the piezoelectric ceramics 14 provided on the outer peripheral surface of the stator 11 are mutually connected. A sinusoidal AC voltage having a phase difference of 90 ° is applied, and a wavefront of an axial traveling wave is formed on the inner peripheral surface of the through-hole 12 on the inner peripheral surface 12a. Occurs. By this elliptical motion, the shaft 13 frictionally engaged with the inner peripheral surface 12a is frictionally driven in the direction opposite to the traveling direction of the traveling wave. As the shaft 13 linearly drives in the axial direction, the cam projection 43 slides in the cam groove 42, and the shaft 13 is driven to rotate at the same time as the shaft 13 is linearly driven by this cam mechanism.

  As described above, the helical cam groove 42 is formed in the shaft 13 of the piezoelectric actuator 10d that performs linear drive, and the cam protrusion 43 that engages with the cam groove 42 is provided in the stator 11. The shaft 13 can be driven to move linearly in the axial direction and at the same time can be driven to rotate about the axis. By providing the helical cam groove 42 and the cam projection 43 in the piezoelectric actuator that performs rotational driving, the piezoelectric actuator may be driven to rotate and drive straight.

  In the present embodiment, two electrodes 15 and 16 that are electrically separated are formed on the piezoelectric ceramic 14, and an AC voltage having a phase difference of 90 ° is applied to the electrodes 15 and 16, so that the inner circumference of the through-hole 12 Although the shaft 13 is driven linearly by generating an elliptical motion in the axial direction on the surface 12a, two piezoelectric ceramics are attached to the outer peripheral surface of the stator 11 in the axial direction of the shaft 13, and the phase is applied to the two piezoelectric ceramics. Alternatively, an AC voltage that is 90 ° different from each other may be applied to generate an elliptical motion in the axial direction on the inner peripheral surface 12a of the through hole 12 to drive the shaft 13 straightly.

  FIG. 16 is a cross-sectional view showing a modification of the setting unit for setting the frictional contact pressure. The stator 11 shown in FIG. 16A is formed with a slit 44 cut in the center direction from a pair of diagonals and extending in the axial direction. The slit 44 is formed on the outer peripheral surface of the shaft 13 and the inner periphery of the stator 11. It is a setting part which sets the friction contact pressure with the surface 12a. By applying a compressive force in the lateral direction to each outer peripheral surface of the stator 11 by the slits 44 as shown by arrows, the stator 11 can be elastically deformed in the lateral direction, and the outer peripheral surface of the shaft 13 and the inner peripheral surface of the stator 11. Appropriate frictional contact pressure can be applied to 12a. The stator 11 provided with such a setting unit may be used as the stator 11 of the piezoelectric actuators 10a to 10d. Further, as shown in FIG. 16B, a slit 44 cut in the radial direction from the inner peripheral surface 12a and extending in the axial direction may be formed as a setting portion.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, the slider 37 may be provided on the inner peripheral surface 12a of the stator 11, or the slider 37 may be partially cut out. Further, the electrodes 24 to 27 provided on the piezoelectric ceramic 23 are electrically separated in the axial direction in the same manner as the linear motion electrode pair having the electrodes 15 and 16, and are in phase with the axial electrode pair. The AC voltage may be applied.

It is a perspective view of the piezoelectric actuator which is one embodiment of the present invention. (A) is the 2A-2A sectional view taken on the line in FIG. 1, (B) is the 2B-2B sectional view taken on the line in FIG. FIG. 3 is a cross-sectional view of the stator in FIG. 1 taken along line 3-3. It is a circuit diagram which shows the connection state of the piezoelectric actuator shown in FIG. 1, and alternating current power supply. It is a schematic sectional drawing which shows the principle of operation of the piezoelectric actuator shown in FIG. It is a perspective view of the piezoelectric actuator which is other embodiment of this invention. FIG. 7 is a cross-sectional view taken along line 7-7 in FIG. 6. It is a circuit diagram which shows the connection state of the piezoelectric actuator shown in FIG. 6, and alternating current power supply. It is a perspective view of the piezoelectric actuator which is other embodiment of this invention. (A) is the 10A-10A sectional view taken on the line in FIG. 9, (b) is the 10B-10B sectional view taken on the line in FIG. FIG. 10 is a circuit diagram showing a connection state between the piezoelectric actuator shown in FIG. 9 and an AC power supply. It is a perspective view of the piezoelectric actuator which is other embodiment of this invention. FIG. 13 is a sectional view taken along line 13-13 in FIG. FIG. 14 is a cross-sectional view taken along line 14-14 in FIG. It is a circuit diagram which shows the connection state of the piezoelectric actuator shown in FIG. 12, and alternating current power supply. It is sectional drawing which shows the modification of the setting part which sets a friction contact pressure.

Explanation of symbols

10a to 10d Piezoelectric actuator 11 Stator 11a, 11b Stator body 11c Connecting member 12 Through hole 12a, 12b Inner peripheral surface 13 Shaft 14 Piezoelectric ceramics (first piezoelectric element)
15 to 17 Electrodes 18 and 19 AC power supply 20 and 21 Stretchable region 23 Piezoelectric ceramics (second piezoelectric element)
24 to 27 Electrodes 28 to 31 AC power supply 32 to 35 Extendable region 37 Slider 38 Slit (setting unit)
39 Stopper 40 Anti-vibration support base 42 Cam groove 43 Cam projection 44 Slit (setting part)

Claims (12)

A piezoelectric actuator that drives the shaft linearly in the axial direction and at the same time rotationally drives the shaft center;
A stator having a through hole having an inner peripheral surface frictionally engaged with the outer peripheral surface of the shaft, the shaft being mounted so as to be linearly reciprocable and rotatable;
A first piezoelectric element provided on the outer peripheral surface of the stator;
At least two electrodes that are electrically separated in the axial direction of the shaft and apply alternating voltages of different phases to the first piezoelectric element;
At least two second piezoelectric elements respectively provided on the outer peripheral surface of the stator so as to be shifted from each other in the rotational direction of the shaft;
A piezoelectric actuator, comprising: an electrode provided on each of the second piezoelectric elements, for applying an alternating voltage having a different phase to each of the second piezoelectric elements. A piezoelectric actuator that drives the shaft linearly in the axial direction and at the same time rotationally drives the shaft center;
A stator having a through hole having an inner peripheral surface frictionally engaged with the outer peripheral surface of the shaft, the shaft being mounted so as to be linearly reciprocable and rotatable;
At least two first piezoelectric elements provided in the axial direction of the shaft on the outer peripheral surface of the stator;
An electrode provided on each of the first piezoelectric elements, for applying an alternating voltage having a different phase to each of the first piezoelectric elements;
At least two second piezoelectric elements respectively provided on the outer peripheral surface of the stator so as to be shifted from each other in the rotational direction of the shaft;
A piezoelectric actuator, comprising: an electrode provided on each of the second piezoelectric elements, for applying an alternating voltage having a different phase to each of the second piezoelectric elements.   3. The piezoelectric actuator according to claim 1, wherein the first piezoelectric element and the second piezoelectric element are provided in the stator while being shifted from each other in the axial direction of the shaft.   3. The piezoelectric actuator according to claim 1, wherein the first piezoelectric element and the second piezoelectric element are provided in the stator while being shifted from each other in the rotation direction of the shaft.   5. The piezoelectric actuator according to claim 1, wherein the first piezoelectric element is provided on the stator so as to face each other around the shaft, and the second piezoelectric element is attached to the shaft. A piezoelectric actuator characterized in that the stator is provided on the stator so as to face each other as a center.   The piezoelectric actuator according to any one of claims 1 to 5, wherein an electrode provided on each of the second piezoelectric elements is separated in an axial direction of the shaft, and the pair of separated electrodes includes A piezoelectric actuator, wherein an alternating voltage having the same phase is applied. A piezoelectric actuator that drives the shaft linearly in the axial direction and at the same time rotationally drives the shaft center;
A stator having a through hole having an inner peripheral surface frictionally engaged with the outer peripheral surface of the shaft, the shaft being mounted so as to be linearly reciprocable and rotatable;
A piezoelectric element provided on the outer peripheral surface of the stator;
At least two electrodes that are electrically separated in the axial direction of the shaft and that apply alternating voltages of different phases to the piezoelectric element;
A cam groove formed on either the outer peripheral surface of the shaft or the inner peripheral surface of the stator and having a spiral portion;
A piezoelectric actuator having a cam protrusion provided on the other of the outer peripheral surface of the shaft or the inner peripheral surface of the stator and engaging with the cam groove. A piezoelectric actuator that drives the shaft linearly in the axial direction and at the same time rotationally drives the shaft center;
A stator having a through hole having an inner peripheral surface frictionally engaged with the outer peripheral surface of the shaft, the shaft being mounted so as to be linearly reciprocable and rotatable;
At least two piezoelectric elements provided in the axial direction of the shaft on the outer peripheral surface of the stator;
An electrode for applying an alternating voltage having a different phase to each piezoelectric element;
A cam groove formed on either the outer peripheral surface of the shaft or the inner peripheral surface of the stator and having a spiral portion;
A piezoelectric actuator having a cam protrusion provided on the other of the outer peripheral surface of the shaft or the inner peripheral surface of the stator and engaging with the cam groove.   The piezoelectric actuator according to any one of claims 1 to 8, wherein the piezoelectric actuator is set on at least one of the shaft and the stator and sets a frictional contact pressure between an outer peripheral surface of the shaft and an inner peripheral surface of the stator. A piezoelectric actuator comprising a portion.   10. The piezoelectric actuator according to claim 9, wherein the setting portion is a slit that extends in an axial direction by being cut in a central direction of the shaft, and sets the frictional contact pressure by elastic deformation of the shaft. Actuator.   10. The piezoelectric actuator according to claim 9, wherein the setting portion is a slit that extends in an axial direction by being cut in a center direction of the stator, and sets the frictional contact pressure by elastic deformation of the stator. 10. Actuator.   The piezoelectric actuator according to any one of claims 1 to 11, wherein a slider made of an abrasion-resistant material is provided on one of the shaft and the stator.

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