JP2006203964A - Magnetostrictive actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetostrictive actuator, having a higher input and higher efficiency compared with an actuator that uses a piezoelectric element. <P>SOLUTION: The magnetostrictive actuator comprises a magnetostrictive element connected to a driving body, a magnetic field generation means that imparts a magnetic field to the magnetostrictive element, and a movable member that is pressure-welded to or abutted against the tip of the driving body, and moves the movable member, by developing circular motion at the tip of the driving body by making the magnetic field produced by the magnetic field generation means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a magnetostrictive actuator using a magnetostrictive element as a drive element, and more particularly to a magnetostrictive actuator that is optimal for an apparatus that requires precise positioning.

  Conventionally, as disclosed in Japanese Patent Application Laid-Open No. 7-184382 (Patent Document 1), a voltage is applied to one piezoelectric element, and displacement of the piezoelectric element generated thereby is used to resonate the piezoelectric element member. The object is moved by forming an elliptical motion in the power transmission unit.

  FIG. 3 shows this state. The actuator for moving the object 108 includes at least one rectangular piezoelectric plate 103 having long edges 100 and 101 and short edges 102 and first and second surfaces, and a first edge. Electrodes 104-107 attached to the first and second surfaces, and an actuable ceramic spacer 109 attached to the center of the first edge of the edge and pressed against the object 108, with an elastic force of the first Applied to the center of the second edge opposite the one edge, thereby pressing the ceramic spacer 109 against the object 108 and causing at least a portion of the electrodes 104-107 to pass an alternating or asymmetric single pole pulse voltage. Either one is energized.

  Further, in the device described in US Pat. No. 6,373,170 (Patent Document 2), as shown in FIG. 4, the displacement of the piezoelectric elements 110 and 111 is used to cause a resonance phenomenon in the vibrating body 112. The object 114 is moved by the displacement of the elastic body 113 caused thereby. In this case, a coil spring is used for preloading the actuator.

Further, the actuator disclosed in Japanese Patent Application Laid-Open No. 2002-101676 uses the displacement of the piezoelectric element to cause a resonance phenomenon in the vibrating body and drives it to drive the rotating body. FIG. 5 shows the configuration. A chip member 122 is provided at the intersection of two piezoelectric elements 120 and 121 arranged at a predetermined angle, and a base member 123 that holds the piezoelectric elements 120 and 121 is added together. The tip member 122 is brought into pressure contact with the rotor 126 by the pressure member 124. The pressurizing member 124 is provided with a pressurizing force adjusting mechanism 125, and the pressurizing force is adjusted so that the locus of the tip member 122 has a desired shape while adjusting the pressurizing force.
JP 7-184382 A US Pat. No. 6,373,170 JP2002-101676

  Any of the above-described conventional actuators uses a piezoelectric element as a driving element, and a piezoelectric actuator using a resonance phenomenon of the actuator cannot obtain a sufficient driving force because the displacement and output of the piezoelectric element are small. In addition, when a piezoelectric element is used, the energy conversion efficiency between electric power and driving amount is poor, and there is a problem in durability of the element itself.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a magnetostrictive actuator that uses a highly durable magnetostrictive element instead of a piezoelectric element, and has a large actuator output and high efficiency. There is to do.

  The present invention relates to a magnetostrictive actuator using a magnetostrictive element, and the object of the present invention is to provide a magnetostrictive element joined to a driving body, a magnetic field generating means for applying a magnetic field to the magnetostrictive element, A movable member abutted on, and a magnetic field is generated by the magnetic field generating means to cause a circular motion at the tip of the driving body to move the movable member. This is achieved more effectively by using a coil wound around the magnetostrictive element.

  The present invention relates to a magnetostrictive actuator using a magnetostrictive element, and the object of the present invention is to provide at least two or more magnetostrictive elements that are arranged so as to intersect with each other and that are joined to a driver, and wound around each of the magnetostrictive elements. A coil that is connected to the other end of each magnetostrictive element in a V-shaped recess and applies a preload, and a movable member that is pressed against or abutted against the tip of the driving body. This is achieved by supplying a high-frequency current having an arbitrary phase difference to cause a circular motion at the tip of the drive body to move the movable body.

Further, the object of the present invention is to make the frequency of the high-frequency current substantially equal to the natural frequency of the magnetostrictive element and the vibrating body, or the material of the magnetostrictive element is centered on Tb _0.3 Dy _0.7 Fe ₂ . By having a compound as a main component, or by providing an elastic hinge on the vibrating body and applying the preload by the elastic hinge, or by configuring the driving body and the vibrating body with a ceramic material, Effectively achieved.

  Since the actuator of the present invention uses a magnetostrictive element as a drive element, an actuator with higher output and higher efficiency can be realized as compared with a piezoelectric element. Moreover, it is excellent in durability and energy conversion efficiency compared with the case of a piezoelectric element.

  The present invention uses a magnetostrictive element instead of a piezoelectric element as a driving element. Since the actuator uses a magnetostrictive element, it is possible to realize an actuator with higher output and higher efficiency than a piezoelectric actuator.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows an embodiment of the present invention, in which one end portions of two magnetostrictive elements 20 and 30 arranged in a crossing manner are joined to a driver 1 and the other end portions of the magnetostrictive elements 20 and 30 are vibrated. It is joined to the V-shaped recess 15 of the body 10. Magnetic field generating coils 21 and 31 are wound around the magnetostrictive elements 20 and 30, respectively, and a high frequency current is supplied to the coils 21 and 31. The vibrating body 10 is provided with three elastic hinges for giving an elastic force as a preload, that is, an N-shaped elastic hinge 11, an inverted N-shaped elastic hinge 12, and a linear elastic hinge 13. The vibrating body 10 is fixed with fixing screws 14 provided at four corners. The elastic hinges 11 and 12 are provided symmetrically with respect to the driving body 1, and the elastic hinge 13 is provided at the bottom of the vibrating body 10. The shape of the elastic hinges 11 and 12 may be alternative, that is, the elastic hinge 11 may have an inverted N shape and the elastic hinge 12 may have an N shape.

  Further, the distal end portion of the driving body 1 is in pressure contact with or in contact with the movable member 2 to be moved. The pressure contact force or contact force between the driving body 1 and the movable member 2 is given by a well-balanced adjustment by the hinges 11 to 13 provided on the vibration body 10.

  In such a structure, when a sinusoidal high-frequency current having a phase difference as shown in FIGS. 2A and 2B is supplied to the coils 21 and 31, a magnetic field is generated in the coils 21 and 31, and the magnetostrictive element. 20 and 31 are deformed, and the driving body 1 repeatedly performs a circular motion or an elliptical motion according to the phase difference. Moves in the X direction shown in the figure. If the relationship of the phase difference of the supply current is reversed, the movable member 2 moves in the direction opposite to X in the figure.

  When the frequency of the sine wave high frequency is set to a value in the vicinity of the resonance frequency of the actuator itself, the vibration amplitude of the driving body 1 increases, and the driving speed of the movable member 2 can be increased, that is, the amount of movement per unit time can be increased. Moreover, the material of the drive body 1 and the movable member 2 is preferably a material that has little wear and can obtain a large frictional force. For example, a ceramic material such as silicon nitride, silicon carbide, zirconia, or alumina is preferable.

  Next, the magnetostrictive element used in the present invention will be described.

The magnetostriction phenomenon is a phenomenon in which a shape change occurs when a magnetic field is applied to a magnetic material. A material having this property at room temperature is called a magnetostrictive material (magnetostrictive element). As these magnetostrictive materials, in addition to single element systems such as Fe, Ni, and Co, compound-based materials such as Co—Fe alloys, NiFe ₂ O ₄ , CoFe ₂ O ₄ , and Fe ₃ O ₄ can be cited. In particular, by combining rare earth elements such as Y, Pr, Sm, Tb, Dy, Ho, Er, and Tm with metal elements such as Fe, Ni, and Co, large magnetostrictive displacement can be generated. In particular, these magnetostrictive materials can generate a large stress of several N / mm ² , and by using this material to form a drive unit, it is possible to obtain a compact and large driving force compared to the case where a piezoelectric element is used. It is. It is also possible to control the preload amount from the outside. In particular, a magnetostrictive material having a central composition of Tb _0.3 Dy _0.7 Fe ₂ having a Laves structure cubic crystal of RT ₂ (R: lanthanoid element, T: iron group transition element) has a displacement strain of 600 to 1000 ppm and 8 N / mm ^2. Therefore, the actuator has optimum characteristics as a driving member of the actuator of the present invention.

  As the magnetostrictive element having the above composition, a single crystal element and a sintered element are commercially available, but when used as a driving unit for an actuator, for example, a sintering element disclosed in Japanese Patent Application Laid-Open No. 2002-129274. The body is preferred. Since the sintered body obtained by such a powder molding process can have an arbitrary shape from the beginning, a member having higher accuracy than that produced by cutting a single crystal material can be manufactured at a low cost. However, when a sintered magnetostrictive element is used, if the porosity is 10% or more, the function is remarkably deteriorated due to internal oxidation. Therefore, the porosity is 10% or less. In such a case, it is desirable to make it 5% or less. Further, since the vacancies become a stress concentration source and the element strength is remarkably reduced, the maximum vacancy diameter of the surface portion of the member is desirably 500 μm or less, preferably 200 μm or less.

  In the above-described embodiment, an elastic hinge is used as a means for obtaining the preload, and the preload adjustment by the elastic hinge is arbitrarily adjusted for the spring constant in the vertical direction and the horizontal direction by changing the thickness of the elastic hinge. However, it is also possible to use a coil spring.

  In the above description, an example in which a magnetic field is generated by supplying a high-frequency sine wave to a coil has been described. However, driving with a high-frequency rectangular wave is also possible. The driving body is driven by using two magnetostrictive elements arranged so as to intersect with each other, but it is also possible to use a plurality of three or more magnetostrictive elements. Furthermore, in the above description, the vibrating member side is fixed and the movable member is moved. However, the movable member side may be fixed and the vibrating member side may be moved.

  According to the actuator of the present invention, a high output and a highly efficient movement amount can be obtained, so that the actuator can be widely used for linear drive units that require precise positioning, such as machine tools, electrical equipment, communication equipment, and automobiles.

It is a block diagram which shows the Example of this invention. It is a figure which shows the example of a waveform of the drive signal of this invention. It is a block diagram which shows the example of the conventional piezoelectric actuator. It is a perspective view which shows the other example of the conventional piezoelectric actuator. It is a block diagram which shows the other example of the conventional piezoelectric actuator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Drive body 2 Movable member 10, Vibrating bodies 11-13 Elastic hinge 14 Fixing screw 15 Recess 20, 30 Magnetostrictive element 21, 31 Coil

Claims (7)

A magnetostrictive element joined to a driving body, a magnetic field generating means for applying a magnetic field to the magnetostrictive element, and a movable member pressed against or in contact with the tip of the driving body, and generating a magnetic field by the magnetic field generating means The magnetostrictive actuator is characterized in that the movable member is moved by causing a circular motion at the tip of the driving body. 2. The magnetostrictive actuator according to claim 1, wherein the magnetic field generating means is a coil wound around the magnetostrictive element. At least two or more magnetostrictive elements arranged so as to intersect with each other and joined to the driving body, a coil wound around each of the magnetostrictive elements, and the other end of each of the magnetostrictive elements joined to a V-shaped recess. And a driving member that applies a preload and a movable member that is pressed against or abutted against the tip of the driving body, and supplies the coil with a high-frequency current having an arbitrary phase difference, thereby providing the driving body. A magnetostrictive actuator, wherein the movable member is moved by causing a circular motion at a tip end of the magnet. The magnetostrictive actuator according to claim 3, wherein the frequency of the high-frequency current is substantially equal to a natural frequency of the magnetostrictive element and the vibrating body. The magnetostrictive actuator according to claim 3 or 4, wherein a material of the magnetostrictive element is mainly composed of a compound having a central composition of Tb _0.3 Dy _0.7 Fe ₂ . The magnetostrictive actuator according to claim 3, wherein an elastic hinge is provided on the vibrating body, and the preload is applied by the elastic hinge. The magnetostrictive actuator according to claim 3, wherein the driving body and the vibrating body are made of a ceramic material.

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