JP2013183563A - Ultrasonic actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic actuator from which a high torque driving force can be output, by suppressing increase in the resonance frequency of ultrasonic vibration, thereby obtaining a large vibration amplitude.SOLUTION: In the ultrasonic actuator including a stator 1 having ultrasonic wave generation elements 3a, 3b, 3c, 3d, and a columnar actuator 2 inserted into the stator and held in place, and rotates and/or acts directly, the stator is provided with a plurality of holes h1, h2 in the surface and/or the interior of at least two sets of surfaces 11, 12, 13, 14 facing each other.

Description

  The present invention relates to an ultrasonic actuator, and more particularly to an ultrasonic actuator that enables high torque output.

  In conventional ultrasonic actuators, a vibrator combining multiple electrostrictive elements or magnetostrictive elements is incorporated into an elastic body, and a traveling wave is generated by combining a transverse wave and a longitudinal wave excited on the surface of the elastic body. There is a configuration that converts the movement into a unidirectional movement of the child, and the rotation is applied to the rotor by using the actuator as a rotor (see Patent Document 1).

  However, the actuator having the above configuration is required to be provided with a pressing mechanism for pressing the elastic body and the actuator (rotor) in pressure. Further, in order to rotate the rotor, the elastic body is formed in an annular shape, and the disk-shaped rotor that is in contact with the annular ring is configured to be in frictional contact. It was not suitable for the drive device to be converted.

  Therefore, an ultrasonic actuator for driving a columnar or cylindrical actuator (shaft member or cylindrical rotor) has been developed (see Patent Documents 2 to 4). In these technologies, a stator that is in frictional contact with a columnar or cylindrical actuator is formed in a cylindrical shape, and in addition to a configuration in which piezoelectric elements are scattered on the outer surface of the cylindrical stator (Patent Document 2). In this configuration, a piezoelectric element is provided on the inner surface of the cylindrical stator, and an actuator is brought into contact with the inside of the stator via a friction material band (Patent Document 3). Furthermore, there has been a configuration in which a polarization electrode is arranged on one surface of a cylindrical stator (stator) and a full surface electrode is provided on the other surface (Patent Document 4).

  However, when the stator has a cylindrical shape, the piezoelectric element provided on the surface has to be shaped along the cylindrical surface, and its manufacture is not easy. In addition, the excitation of ultrasonic vibration for operating the rotor is complicated, and it is difficult to reduce the size by the same configuration. Therefore, the inventors of the present application have developed an ultrasonic actuator that can be miniaturized (see Patent Documents 5 and 6).

JP 59-96881 A Japanese Utility Model Publication No. 2-83695 Japanese Patent Laid-Open No. 3-198672 Japanese Patent Laid-Open No. 10-210776 WO2008 / 038817 JP 2009-261494 A

  In the technique disclosed in Patent Document 5 described above, a stator having a quadrangular outer peripheral contour in a cross section perpendicular to the axial direction of the actuator hole is made of a metal material such as iron, stainless steel, aluminum, copper, etc. It was the structure which attaches an ultrasonic wave generation element to. In the above technique, in order to improve the driving torque of the actuator, it is necessary to optimally set the friction between the stator and the actuator. Since it is difficult to adjust in micron units, in the technique disclosed in the above-mentioned Patent Document 6, the stator is constituted by a plurality of parts, and the size of the actuator hole of the stator according to the diameter of the actuator. Was configured to be adjustable.

  However, even if the frictional state between the stator and the actuator is optimally set, there is a case where the torque that should be originally generated cannot be obtained. The reason is considered to be that the amplitude of the ultrasonic vibration that resonates decreases as the resonance frequency of the ultrasonic vibration excited by the ultrasonic generating element such as a piezoelectric element increases. This was a serious problem when the actuator was downsized.

  The present invention has been made in view of the above points, and its purpose is to output a high torque driving force by obtaining a large vibration amplitude by suppressing an increase in the resonance frequency of ultrasonic vibration. It is to provide an ultrasonic actuator that can be made to operate.

  Accordingly, the present invention provides an ultrasonic actuator comprising a stator having an ultrasonic wave generating element and a columnar actuator that is inserted and held in the stator and rotates and / or linearly moves. It is characterized by having a plurality of holes inside.

  According to the above configuration, since there are a plurality of holes on the surface and / or inside of the stator, the amount of strain with respect to the stress received from the outside becomes larger than that of a bulk (bulk) made of the same material. The overall Young's modulus is reduced. The resonance frequency can be obtained from the square root of the value obtained by dividing the Young's modulus by the density. When the Young's modulus decreases, the value (resonance frequency) decreases. As a result, the amplitude of the resonating vibration can be increased and a large torque can be obtained. Here, the Young's modulus of the entire stator means the Young's modulus (stress / strain) when the stator is observed as one lump. The Young's modulus inherent to the material does not change, but the entire stator is strained. As a result, the Young's modulus as a whole is reduced. For the above reasons, the Young's modulus when the entire stator is observed is sometimes referred to as “apparent Young's modulus”. In the above description, the torque for rotational drive has been mainly described, but the same applies to the thrust force in the forward / backward movement (linear motion) in the linear direction. In the following description, torque will be mainly described, but the same is also true in that case.

  In the above invention, the stator may be made of a porous metal. The porous metal is a metal produced by molding and sintering metal powder, and can be produced by adding a binder and a pore forming material to the metal powder. When such a porous metal is used, the proportion of pores formed in the metal can be adjusted by the amount of pore forming material added, and a stator having a desired Young's modulus can be formed. It becomes.

  In the above-mentioned invention, the air holes of the stator can be constituted by penetrating through holes. According to such a configuration, the whole of the stator is formed by the material existing in the gap between the adjacent through holes, the amount of strain with respect to external stress is further increased, and the Young's modulus of the entire stator is reduced. be able to.

  Further, the holes in the above invention can be holes formed regularly and at equal intervals. With such a configuration, it is possible to avoid that the strain is partially increased (or decreased) in the entire stator and to increase the strain in a uniform state as a whole.

  Further, the present invention provides a hexahedral stator, an actuator hole penetrating through two opposing surfaces of the stator, and a columnar shape that is inserted and held inside the actuator hole and rotates and / or moves linearly. In the ultrasonic actuator comprising an actuator and ultrasonic generating elements mounted on each of the remaining four surfaces of the stator, a plurality of the stators are provided on and / or inside the four surfaces on which the ultrasonic generating elements are mounted. It is characterized by having the following holes.

  According to the above configuration, a plurality of holes are provided on the surface of the surface on which the ultrasonic generating element is mounted, or in a range from the surface to an appropriate depth or a part of the appropriate depth. The vibration excited by the ultrasonic generating element transmits and resonates in the place without the plurality of holes, but the distortion of the portion excited by the vibration increases, and the Young's modulus of the portion decreases. Therefore, the amplitude of the resonating vibration can be increased. In addition, since the shape of the stator is basically composed of a hexahedron, the ultrasonic wave generating element can be mounted on the four sides of the hexahedron, and therefore it is not necessary to match the ultrasonic wave generating element to the shape of the stator. .

  In the above-described configuration, the stator can be made of a porous metal. Since the porous metal can be manufactured into a desired shape by molding metal powder, it is possible to manufacture a hexahedron with a metal having pores as described above.

  Moreover, in the said invention, a void | hole can be comprised by the through-hole which penetrates between two opposing surfaces among the said hexahedron. In such a configuration, since the two opposing surfaces are penetrated, the through hole reaches the operator hole (also penetrates the operator hole), and the ultrasonic generating element The range from the surface where vibration is excited to the hole for the actuator can be distorted in the same state, and the Young's modulus in the range can be adjusted to a similar value.

  Furthermore, the through holes can be configured to be regularly drilled at regular intervals. With such a configuration, for the stator formed in a hexahedron, the internal structure in the range from the four surfaces to the actuator hole can be made uniform, and the vibration excited on the four surfaces is the vibration of the four surfaces. In either case, the vibration is transmitted to the actuator hole in the same manner, and the resonating vibration can be applied to the actuator as well.

  According to the present invention, it is possible to increase the torque of an ultrasonic actuator that can be insufficient in torque when downsized. That is, in the medical field, it can be used as a catheter guiding motor, and a desired torque can be obtained by a fine motor, so that it can be used in a highly invasive medical practice. It can also be used to drive a probe (ultrasound probe) in an intravascular ultrasound device (IVUS: Intravascular Ultrasound) as a diagnostic device inside blood vessels such as peripheral blood vessels and coronary veins using a catheter. It becomes. This IVUS is a device in which a probe is provided at the tip of a catheter, an ultrasonic wave is transmitted from the probe, and a reflected signal is received again by the probe. An image is formed from the reflected signal, and the inner wall of the blood vessel is surrounded. As a driving force for rotating in the direction, the minute motor of the present invention can be used. Furthermore, when attached to the distal end of an endoscope, it can function as a device for identifying the position of the distal end, enabling high-speed localization during drug administration or partial resection, and burdening the patient. Can be reduced.

  Furthermore, in the field of cameras, it can be used as a lens driving motor for autofocus and a driving motor for a zoom lens. By mounting a light and small motor on the motor, it is possible to realize weight reduction and size reduction of these cameras. That is, since the motor of the present invention increases the torque per unit mass, the mass of the entire motor for obtaining the desired torque will be reduced, and if the equivalent torque is output, the weight can be reduced. On the other hand, when a motor having an equivalent weight is mounted, a high torque can be obtained. Therefore, even when used as a drive motor for a movable part (various parts to be driven) in the robot field, it is possible to reduce the weight and size, and the motor in the field of other industrial machines (for example, automobiles). Can also be used.

  Further, in the present invention having a configuration in which ultrasonic generating elements are mounted on four sides of a hexahedral stator, the four sides can be handled as a plane when downsizing, so that the shape of the stator is adjusted. There is no need to provide an ultrasonic generating element having a complicated shape, and an ultrasonic generating element that can be mounted on a flat surface can be used. Thereby, the whole ultrasonic actuator can be manufactured at low cost.

It is a perspective view which shows 1st embodiment of an ultrasonic actuator. (A) is a figure which shows the relationship between a stator and an actuator, (b) is a figure which shows the state of the void | hole provided in a stator. It is a perspective view which shows the modification of 1st embodiment of an ultrasonic actuator. (A) is a perspective view showing a second embodiment of the ultrasonic actuator, (b) is an exploded view of a part thereof, and (c) is an exploded view showing a modification. (A) is a perspective view which shows 3rd embodiment of an ultrasonic actuator, (b) is a perspective view which shows 4th embodiment. It is a perspective view which shows 5th embodiment of an ultrasonic actuator.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a first embodiment of the present invention. 1A is a perspective view of the upper surface side of the stator, and FIG. 1B is a perspective view of the bottom surface side. As shown in this figure, the stator 1 has an overall shape of a hexahedron, and an actuator 2 is inserted into an actuator hole, which will be described later, provided on a pair of opposing two surfaces. In addition, piezoelectric elements 3a, 3b, 3c, and 3d as ultrasonic wave generating elements are mounted on the remaining two opposing faces (four faces) 11, 12, 13, and 14 of the hexahedron, respectively. The piezoelectric elements 3a to 3d can generate traveling waves on the inner surfaces of the actuator holes by generating ultrasonic waves on the surfaces 11 to 14, respectively. Thus, by generating an ultrasonic wave by shifting the phase by 90 degrees for each of the surfaces 11 to 14 (for example, shifting the phase by 90 degrees from the plane 11 toward the right side surface 12, the bottom surface 13, and the left side surface 14). The actuator 2 can be rotated. Thus, the torque becomes maximum when the phase is shifted by 90 degrees for each of the four surfaces 11, 12, 13, and 14, and the torque can be adjusted by changing this phase difference.

  In addition, although the stator 1 and the actuator 2 are provided with metal materials, such as iron, stainless steel, gold | metal | money, copper, and titanium, it is not limited to these. That is, it may be selected as appropriate according to the object to be used. For example, if a biocompatible material such as gold or titanium is used, it can be used for driving an endoscope in the medical field. These metal materials are not limited to a single material, but may be an alloy or a coated / plated material. That is, by covering the stator 1 and the actuator 2 made of a specific metal material with a metal having biocompatibility such as gold or titanium, it can be used in the medical field as described above.

  Needless to say, the stator 1 and the actuator 2 can be made of different materials. This is because the motor torque greatly depends on the Young's modulus and specific gravity of the stator 1. If a material having a large specific gravity is used, the resonance frequency can be reduced even if the Young's modulus is the same because the density is large in comparison with other materials having the same shape. Therefore, by using a material having a large specific gravity, a high torque can be obtained even if it is the same size as compared with the case of using another material.

  A plurality of holes h1 and h2 are formed in the two opposing surfaces 11 to 14 of the stator 1 having the above-described configuration, and the holes h1 and h2 are opened on the surfaces of the surfaces 11 to 14, respectively. Yes. The piezoelectric elements 3a to 3d are mounted so as to close the openings of the holes h1 and h2. The blockage of the openings by the piezoelectric elements 3a to 3d may block all of the plurality of holes h1 and h2 in the respective surfaces 11 to 14, and a plurality of holes h1 and h2b that are formed as shown in the figure. May be attached so as to partially occlude. Here, the term “hole” means a hole in a hollow state, and if the inside of the hole is hollow, in addition to the configuration that opens on the surface (FIG. 1), as described later, the surface of the stator 1 that does not open on the surface. It is good also as a structure which has a hollow part inside. Even in the case of a hole having a structure opening on the surface, when all the openings are closed as described above, the structure is substantially the same as the structure in which the hollow portion exists inside.

  FIG. 2 is a view showing the stator 1 in a state where the operating element 2 is detached. As shown in FIG. 2A, the stator 1 is provided with an actuator hole 4 penetrating between a pair of opposing two surfaces 15 and 16. As described above, the stator 1 is composed of a hexahedron, and when the opposing surfaces 15 and 16 where the operating hole 4 is to be provided are square, the operating hole 4 is provided in the center of the opposing surfaces 15 and 16. In addition, the positional relationship between the remaining four surfaces 11 to 14 and the inner peripheral surface of the actuator hole 4 is equalized, and the ultrasonic vibration generated on each surface 11 to 14 is evenly transmitted to the inner peripheral surface of the actuator hole 4. In addition, the traveling wave with respect to the surface of the actuator 2 inserted through the inside can be applied to the same degree.

  Moreover, as shown in FIG.2 (b), the stator 1 of this embodiment comprises hole h1, h2 by the through-hole for every group among two sets of opposing surfaces 11-14. That is, a hole (through hole) h1 is formed so as to reach the bottom surface 14 from the flat surface 11, and a hole (through hole) h2 is formed so as to reach the left side surface 13 from the right side surface 12. is there. Therefore, as shown in the figure, the holes (through holes) h1 and h2 are also opened on the inner peripheral surface of the actuator hole 4.

  Here, although the holes or through holes h1 and h2 can be formed mechanically, the stator 1 may be configured using a metal material having holes. Such metal materials include porous metals. This porous metal is formed by sintering metal powder and forming it into a lump shape, and is manufactured by filling the pore-forming material together with the metal powder, followed by forming and sintering. As the pore forming material, a material that is solid at room temperature but melts and evaporates by heating is used. Note that a binder is filled for bonding metal powders, and the metal powders are bonded so that pores formed by disappearance of the pore forming material are maintained. This type of porous metal can uniformly provide pores throughout the material by dispersing the pores throughout the metal material. Further, since the pore content can be adjusted by the addition ratio of the pore-forming material, a desired ratio of porosity can be obtained. In addition, as this kind of porous metal, for example, there is a porous metal manufactured by Taisei Kogyo Co., Ltd.

  Since this embodiment is configured as described above, by providing a plurality of holes (or through holes) h1 and h2 in the stator 1, the entire stator 1 becomes a structure that is easily distorted. The Young's modulus (this apparent Young's modulus may be referred to as the apparent Young's modulus) can be small. That is, the Young's modulus is a value obtained by dividing the stress by the strain (Young's modulus = stress / strain). If the strain increases compared to when the same stress is applied, the overall Young's modulus (apparent Young's modulus) Rate) can be reduced.

  Furthermore, since the resonance frequency is calculated by the square root of the value divided by its Young's modulus and density, by reducing the apparent Young's modulus, if the density is the same, the resonance frequency becomes smaller. Accordingly, the amplitude can be increased. The density is determined by the material used for the stator 1 and does not change even if the holes h1 and h2 are drilled. Therefore, the resonance frequency can be reduced as described above. .

  On the other hand, in order to rotate the actuator (which may be referred to as a rotor) 2 by vibration or to linearly move (linear movement in the forward / backward direction), the surface of the actuator 2 in contact with the stator 1 is used. The periodic traveling wave generated by the stator 1 needs to be brought into frictional contact sequentially in the traveling direction. At that time, in order to increase the torque of the driving force, it is necessary to increase the frictional force of the frictional contact or increase the amplitude of the vibration. If the increase in the frictional force cannot be expected, the amplitude is increased. Further, when the frequency of the resonance vibration is large, the fluctuation of the cycle becomes high speed, and therefore the amplitude tends to be small. When the frequency is small, the amplitude is large. Therefore, in order to increase the amplitude, the torque can be increased as a result by reducing the frequency of the resonance vibration.

  By the way, in order to reduce the resonance frequency by using the same material stator, firstly, a method of decreasing the Young's modulus or secondly, increasing the density can be considered. If the materials are the same, it may be possible to increase the density by increasing the purity, but the rate does not change greatly. Therefore, consider reducing the Young's modulus. The Young's modulus is assumed to be the same Young's modulus when focusing on the material itself. This is because everything is measured and calculated for a massive material. However, if, for example, a material having a hollow portion has the same appearance but strain increases when stress is applied, the Young's modulus as a whole can be reduced. Therefore, in the present invention, the stator 1 is processed to artificially reduce the Young's modulus as a whole.

  In order to verify the above, we analyzed how the frequency of resonant vibration changes by the finite element method. The model for analysis is a cubic stator 1 having a structure as shown in FIGS. The stator 1 is a cube having a side length of 14 mm. A through hole having a diameter of 10 mm is formed on a pair of opposing two surfaces 15 and 16 to form an actuator hole 4, and the remaining four surfaces (two sets) 36 through holes (holes) h1 and h2 each having a diameter of 1.8 mm are provided on two opposing surfaces (11 to 14). The model as a comparative example has a configuration in which a through-hole (actuator hole 4) having a diameter of 10 mm is provided as a hole for an actuator with a cube having a side length of 14 mm. For any stator, the material was phosphor bronze (C5191), and the piezoelectric element assumed was Z0.6T10 × 10S-W (material C82) manufactured by Fuji Ceramic. The operating element was stainless steel, and a fitting tolerance of 9.998 mm in diameter was assumed.

  In this case, the model of the comparative example had a natural vibration frequency of 68 kHz, whereas the model for analysis was 52 kHz, which was a decrease of about 24%. Thus, by changing the structure of the stator, the resonance frequency is lowered, thereby increasing the amplitude.

  As described above, even if the same material as the massive stator is used, it is possible to greatly reduce the resonance frequency by providing the holes h1 and h2 as in the present embodiment. Therefore, as a result of the above, the amplitude increases, and the torque for the actuator 2 can be increased correspondingly.

  Next, a modification of the first embodiment will be described. FIG. 3 is a perspective view showing a modification thereof. In this modification, as shown in the drawing, the surfaces 11 to 14 (the left side surface 13 and the bottom surface 14 are not shown) in which holes h1 and h2 are formed in the stator 1 are respectively arranged in the axial direction of the actuator 2. Two piezoelectric elements 31, 32 (the piezoelectric elements 31a, 32a on the plane 11 and the piezoelectric elements 31b, 32b on the right side 12) are arranged in series (left side 13 and bottom 14 not shown). Is also provided with a piezoelectric element in the same state).

  With the above configuration, linear movement (linear sliding in the forward and backward direction) is possible by shifting the phase of the ultrasonic waves generated by the two types of piezoelectric elements 31 and 32 mounted on the same surface. It is to make. At this time, when the phases of the two types of piezoelectric elements 31 and 32 in series are shifted by 90 degrees, the thrust force becomes maximum, and the output is adjusted by changing the phase difference (the desired thrust force is applied to the actuator 2). Can). Further, when the two types of piezoelectric elements 31 and 32 have the same phase and the phases are shifted between adjacent surfaces, for example, the piezoelectric elements 31a and 32a on the plane 11 are unified with the same phase, and the piezoelectric element on the right side surface 12 is obtained. 31b and 32b are unified by a phase different from that of the piezoelectric elements 31a and 32a on the plane 11 (the left side surface 13 and the bottom surface 14 (not shown) are also appropriately shifted in phase). The actuator 2 can be rotated similarly to the case where the piezoelectric element is provided. In this case, the rotational torque becomes maximum when the phase unified on each surface is shifted by 90 degrees. Furthermore, there may be an aspect in which both the above states are mixed. In other words, the phases of the two types of piezoelectric elements 31 and 32 on each surface are shifted, and the phases between adjacent surfaces are also shifted. In such a case, it is possible to perform control such that the operating element 2 is simultaneously rotated while being moved linearly. Such a control of the moving element 2 can be performed by individually adjusting the phase of the AC voltage applied to each piezoelectric element 31a, 32a, 31b, 32b.

  Next, a second embodiment will be described. FIG. 4A is a perspective view of the stator in the second embodiment. As shown in this figure, the stator 101 is composed of individual members in which an upper part 105 and a lower part 106 are separated, and further, side parts 107 and 108 are inserted between the two parts 105 and 106. Such a configuration makes it possible to adjust the fitting state with an actuator (not shown) when the fine stator 101 is formed. In order to integrate them, methods such as adhesion, welding, and adhesion can be used.

  The hole h101 in this embodiment is not a through hole, but is formed by a hole having a predetermined depth. Such a hole h101 can be provided by drilling at an appropriate depth from the surface of the upper part 105 (and the lower part 106). However, as shown in FIG. 4B, a plurality of materials are laminated. You may comprise by.

  That is, as shown in FIG. 4B, the upper portion 105 is composed of an upper layer 151, an intermediate layer 152, and a lower layer 153, and through holes h101a and h101b are formed in the upper layer 151 and the intermediate layer 152, respectively. 153 has a structure in which no through hole is provided. By laminating these three layers 151, 152 and 153, holes having a depth equal to the thickness of the upper layer 151 and the intermediate layer 152 can be formed.

  Furthermore, as an example in which the above configuration is modified, as shown in FIG. 4C, a configuration in which a through hole h101b is provided only in the intermediate layer 152 is conceivable. In such a configuration, the holes exist only in the intermediate layer 15, and no holes are formed in the upper layer 151 and the lower layer 153. Even in such a configuration, since the holes are present in the stator, the apparent Young's modulus can be reduced, so that the object of the present invention can be achieved.

  In the above configuration, when the stator 101 is assembled, no holes are formed on the surfaces of the two opposing surfaces (plane, bottom, left and right side surfaces). Is transmitted to the entire surface, and the vibration can be efficiently applied to the entire stator 101.

  Next, other embodiments will be described. FIG. 5A is a perspective view showing the third embodiment. As shown in this figure, in the present embodiment, in the first embodiment, a pair of opposed surfaces (front and back not shown) 215 (not shown) are also provided in the first embodiment. A through hole h203 is formed. Although not shown, the piezoelectric elements 3a to 3d are mounted on the four surfaces 211 and 212 (not shown), 213 and 214, respectively, as in the first embodiment. In the present embodiment, since the holes h201, h202, h203 are formed on all six surfaces, the apparent Young's modulus can be further reduced.

  FIG. 5B is a perspective view showing the fourth embodiment. As shown in FIG. 5, the holes h301 and h302 are constituted by through holes having a quadrangular cross section. 1 to 5A referred to in the above-described embodiment, the cross-sectional shape of the hole is circular, but the cross-sectional shape of the hole is not limited to a circular shape, The shape may be a quadrangle as in the present embodiment. Furthermore, other shapes such as a triangle or an ellipse may be used as long as processing is easy.

  The embodiments of the present invention are as described above, but the present invention is not limited to these embodiments. For example, in the above-described embodiment, the stators 1, 101, 201, and 301 in the drawings to be referred to are all illustrated as cubes, but are not limited thereto. That is, as in the fifth embodiment shown in FIG. 6, the stator 401 can have a shape elongated in the axial direction of the actuator 402. In this case, a plurality of piezoelectric elements 431 in the axial direction of the actuator 402 are respectively provided on two opposing surfaces (a flat surface 411, a right side surface 412, a bottom surface (not shown), and a right side surface (not shown)) of the stator 401. , 432 can be easily installed. In this case, in the drawing, two piezoelectric elements are arranged in series, but the number thereof may be increased.

  The front and back surfaces of the stator 401 are square, and if an actuator hole is provided in the center of the stator 401, the distance from each surface to the surface of the actuator becomes equal, but this may be rectangular. In such a configuration, the piezoelectric elements may be installed on all of the two opposing surfaces, but the piezoelectric elements may be installed only on any one of the opposing surfaces (for example, the flat surface and the bottom surface). Furthermore, as in the second embodiment (see FIG. 4), the stator may be configured by separate members, and the holes may be configured by through holes or may be disposed inside. If the piezoelectric element can be controlled, it is not necessary to limit the cross-sectional shape of the stator to a square, the cross-sectional shape may be a hexagon or an octagon, and the piezoelectric element can be manufactured by bending it. If it is easy, the stator may be cylindrical.

1, 101, 201, 301, 401 Stator 2, 202, 302, 402 Actuator 3a, 3b, 3c, 3d, 31a, 31b, 32a, 32b, 431a, 431b, 432a, 432b Piezoelectric element 4 Actuator hole 11, 211,311,411 Plane surface 12,212,312,412 Right side surface 13 Left side surface 14 Bottom surface 15 Front surface 16 Rear surface h1, h2, h101, h101a, h101b, h201, h202, h301, h302, h401, h402

Claims (8)

  In an ultrasonic actuator comprising a stator having an ultrasonic generating element and a columnar actuator that is inserted and held in the stator and rotates and / or linearly moves, the stator has a plurality of surfaces and / or interiors. An ultrasonic actuator comprising holes.   The ultrasonic actuator according to claim 1, wherein the stator is a stator made of a porous metal.   The ultrasonic actuator according to claim 1, wherein the stator hole is a through-hole penetrating the stator.   The ultrasonic actuator according to claim 1, wherein the holes are holes formed regularly and at regular intervals.   A hexahedral stator, an actuator hole penetrating through two opposing surfaces of the stator, a columnar actuator that is inserted into and held in the actuator hole, and rotates and / or moves linearly, and the stator In the ultrasonic actuator comprising ultrasonic generating elements mounted on each of the remaining four surfaces, the stator has a plurality of holes on and / or inside the four surfaces on which the ultrasonic generating elements are mounted. An ultrasonic actuator characterized by comprising:   The ultrasonic actuator according to claim 5, wherein the stator is a stator made of a porous metal.   The ultrasonic actuator according to claim 5, wherein the hole is a through-hole penetrating between two opposing faces of the hexahedron.   The ultrasonic actuator according to claim 7, wherein the through holes are through holes formed at regular intervals and regularly.

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