JP2010067734A - Magnetostriction actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetostriction actuator which suppresses unnecessary vibration, enhances waterproofness, and improves the linearity of an actuator without increasing thickness of the actuator. <P>SOLUTION: In the magnetostriction actuator, a movable part 16 and an upper yoke 17 are placed on the same plane, and an adhesive agent 19 is put into an air gap between them. Furthermore, a coil 14 is arranged in the periphery of a magnetostriction element 12, and a magnet 13 is arranged in the periphery of the coil 14. Thus, the actuator is thinned, having its waterproof performance and linear performance improved. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a magnetostrictive actuator used for various acoustic devices.

  A conventional magnetostrictive actuator will be described with reference to FIG.

  FIG. 8 shows a sectional view of the structure of a conventional magnetostrictive actuator.

  In the figure, reference numeral 1 denotes a magnetostrictive element, and a bobbin 3 around which a coil 2 is wound is disposed around the magnetostrictive element 1, and an upper magnet 4 is provided at the upper end of the magnetostrictive element 1 and a lower magnet 5 is provided at the lower end. Are arranged respectively. A movable portion 6 is joined to the upper portion of the upper magnet 4, an upper yoke 7 is joined to the outer periphery of the movable portion 6, and further to the bottom surfaces of the upper yoke 7 and the lower magnet 5, and the coil 2. A lower yoke 8 that bypasses the outer periphery of the lower yoke 8 is disposed. Further, a flange portion 9 is formed on the outer periphery of the bottom surface of the movable portion 6, and a cushion 10 is disposed so as to be sandwiched between the flange portion 9 and the upper yoke 7 with respect to the vibration direction of the movable portion 6. is doing.

  The operation of the magnetostrictive actuator configured as described above will be described below. A closed magnetic circuit 11 is formed by the above-described upper magnet 4, lower magnet 5, movable portion 6, upper yoke 7, and lower yoke 8 to apply a bias magnetic field to the magnetostrictive element 1. As a matter of course, the movable portion 6, the upper yoke 7, and the lower yoke 8 are magnetic materials including iron.

  The coil 2 causes a change in the magnetic field in accordance with a change in the input signal, and the magnetostrictive element 1 causes a dimensional change in accordance with the change in the magnetic field. The dimensional change is transmitted to the outside as vibration through the upper magnet 4 and the movable part 6.

  The cushion 10 is made of an elastic body and suppresses unnecessary vibration of the movable portion 6 to achieve performance stabilization.

For example, Patent Document 1 is known as prior art document information relating to the invention of this application.
JP 2006-311255 A

  In the above-described magnetostrictive actuator, since the cushion 10 that requires an arrangement space of a certain thickness between the upper yoke 7 and the movable portion 6 with respect to the vibration direction of the movable portion 6 is provided, it is difficult to reduce the thickness of the actuator itself. In addition to having the problem of being present, since a gap is required between the outer peripheral side surface of the movable portion 6 and the inner peripheral side surface of the upper yoke 7, there is also a problem in terms of reliability due to the entry of water droplets or foreign matters.

  Further, since the magnetic permeability of the magnetostrictive element 1 is low, if the upper magnet 4 and the lower magnet 5 that generate a bias magnetic field are provided at both ends of the magnetostrictive element 1, sufficient magnetic flux passes through the central part of the magnetostrictive element 1. Therefore, since a uniform magnetic flux density distribution cannot be obtained, the linearity as an actuator deteriorates.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems and aims to suppress unnecessary vibration without increasing the thickness of the actuator and to make the magnetic flux density distribution of the element uniform so as to improve the linearity of the actuator. It is.

  In order to achieve the above object, the present invention particularly provides an elastic body in the gap between the movable portion and the upper yoke disposed on the outer periphery on the same plane as the movable portion, and a magnet on the outer periphery of the coil. It has a configuration.

  The magnetostrictive actuator of the present invention can suppress unnecessary vibration without disposing a cushion in the thickness direction of the magnetostrictive actuator as in the conventional example by disposing an elastic body in the gap between the movable portion and the upper yoke. In addition, the gap is sealed with an elastic body, so that water droplets and foreign matters are prevented from entering the inside. In addition, since a bias magnetic field is applied using a cylindrical magnet having a thickness equal to the length of the magnetostrictive element, the magnetic flux generated from the magnet passes through the entire magnetostrictive element, and good linearity and energy efficiency can be obtained. There is also an effect.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

(Embodiment 1)
FIG. 1 is a structural cross-sectional view of a magnetostrictive actuator according to Embodiment 1 of the present invention.

  In the figure, 12 is a magnetostrictive element, 13 is a cylindrical magnet having a thickness equal to the length of the magnetostrictive element 12, and the magnet 13 is surrounded by the bobbin 15 around which the magnetostrictive element 12 and the coil 14 are wound. And a bias magnetic field is supplied to the magnetostrictive element 12.

  Reference numeral 16 denotes a movable portion joined to the upper end of the magnetostrictive element 12 to transmit the displacement of the magnetostrictive element 12 to the outside, 17 denotes an upper yoke whose upper end is joined to the upper end of the magnet 13, 18 denotes the magnetostrictive element 12 and A lower yoke joined to the lower end of the magnet 13. By performing trimming on the upper side of the outer peripheral side of the movable part 16 and the upper side of the inner peripheral side of the upper yoke 17, a gap is formed between them, and the gap is filled with an elastic adhesive 19.

  Here, by arranging the movable portion 16 and the upper yoke 17 on the same plane, the actuator can be thinned, and the gap between the movable portion 16 and the upper yoke 17 is sealed with an adhesive 19. Therefore, it is possible to prevent product deterioration caused by water droplets or foreign matter entering the inside.

  The operation of the magnetostrictive actuator configured as described above will be described below.

  The magnetostrictive element 12 generates a magnetostrictive displacement by the magnetic field generated from the coil 14, and the movable portion 16 vibrates following the displacement. The elastic adhesive 19 is formed on the outer periphery of the movable portion. Therefore, unnecessary vibration can be suppressed and performance can be stabilized.

  Further, by making the thickness of the magnet 13 equal to the thickness of the magnetostrictive element 12, even when the material of the magnetostrictive element 12 has a low magnetic permeability, the magnet 14 is closed so that the magnetic flux converges at the center of the coil 14, that is, the center of the magnetostrictive element 12. A magnetic circuit can be formed, and by efficiently passing magnetic flux through the entire magnetostrictive element 12, variation in magnetic flux density inside the magnetostrictive element 12 can be suppressed, and good linear characteristics of the actuator can be obtained. .

  In the present embodiment, the adhesive filling the gap between the movable part 16 and the upper yoke 17 has a certain degree of viscosity when unreacted, such as a silicon rubber adhesive, and after the reaction, An adhesive having a certain degree of elasticity is suitable. At that time, the workability of the adhesive filling can be improved by the trimming process respectively applied to the movable portion 16 and the upper yoke 17, and the spread of the adhesive to other than the desired portion is prevented by the viscosity of the adhesive itself. It becomes possible.

  Further, since the magnetostrictive element 12 has the property that the magnetic permeability changes and the displacement characteristics with respect to the magnetic field change when a compressive load is applied, a structure for adding an optimum load inside the actuator is provided, Although a method of applying a load is also conceivable, in the present invention, it is assumed that a load is applied from the outside. Therefore, it is not necessary to provide a structure for applying a load inside the actuator, and the thickness of the actuator does not increase.

(Embodiment 2)
FIG. 2 is a structural sectional view of the magnetostrictive actuator according to the second embodiment of the present invention, and the same parts as those in the first embodiment will be described by omitting the same numbers.

  In FIG. 2, the difference from the first embodiment is that a groove is provided on each of the outer peripheral side surface of the movable portion 16a and the inner peripheral side surface of the upper yoke 17a, or on either side thereof. Such a resilient O-ring 20 is inserted.

  With this configuration, the position of the movable portion 16a can be stably held, and the O-ring 20 can function as a braking body to suppress unnecessary vibration. Furthermore, the vibration damping property can be controlled by appropriately selecting the material of the O-ring 20, and the performance adjustment adapted to the difference in physical properties of the vibrating body can be performed.

(Embodiment 3)
FIG. 3 is a structural cross-sectional view of the magnetostrictive actuator according to the third embodiment of the present invention, and the same parts as those in the first embodiment will be described by omitting the same numbers.

  In the figure, the difference from the first and second embodiments is that a flange is provided on the lower side of the outer peripheral side surface of the movable portion 16b and a flange is provided on the upper side of the inner peripheral side surface of the upper yoke 17b. The elastic space is filled with an elastic adhesive 19b.

  Here, in the configuration of these flanges, it is obvious that the same function as the above-described embodiment is obtained if it is formed on either the movable portion 16b or the upper yoke 17b.

  Also, with this configuration, the amount of adhesive filled between the movable portion 16b and the upper yoke 17b can be increased, and the strength of the device can be further increased.

(Embodiment 4)
FIG. 4 is a structural cross-sectional view of the magnetostrictive actuator according to the fourth embodiment of the present invention, and the same parts as those in the first embodiment will be described by omitting the same numbers.

  In the figure, the difference from the first embodiment is that a vibration transmitting member 21 having a physical property value different from that of the movable portion 16c is joined to the upper end of the movable portion 16c.

  With this configuration, when used for acoustic applications such as panel speakers, the vibration transmitting member 21 is appropriately selected according to the difference in conditions such as the material and size of the panel that is the vibrating body, thereby reproducing the sound suitable for the vibrating body. It becomes possible to do.

  The material of the vibration transmitting member 21 is preferably a non-magnetic material such as aluminum, resin, or rubber.

  Here, the present embodiment describes only the above-described differences with respect to the first embodiment. However, only the above-mentioned differences are changed also in the magnetostrictive actuators of the second and third embodiments. And the same function as described above can be added.

(Embodiment 5)
FIG. 5 is a structural cross-sectional view of a magnetostrictive actuator in the fifth embodiment of the present invention, and the same parts as those in the first embodiment will be described by omitting the same numbers.

  In the figure, the difference from the first embodiment is that a concave portion 22 is formed on the bottom surface of the movable portion 16d and a concave portion 23 is formed on the top surface of the lower yoke 18d in accordance with the shape of the magnetostrictive element 12d.

  With this configuration, the thickness of the device can be reduced, and the alignment of the magnetostrictive element 12d with the movable portion 16d and the lower yoke 18d can be facilitated.

  Here, the present embodiment describes only the above-described differences with respect to the first embodiment. However, only the above-described differences are also applied to the magnetostrictive actuators of the second embodiment, the third embodiment, and the fourth embodiment. Can be changed, and the same function as described above can be added.

(Embodiment 6)
FIG. 6 is a structural cross-sectional view of a magnetostrictive actuator according to the sixth embodiment of the present invention. The same parts as those in the first embodiment will be described by omitting the same numbers.

  In the figure, the difference from the first embodiment is that the magnetostrictive element 12e is formed by insert molding integrally with the bobbin 15e.

  With this configuration, it is possible to reduce the number of man-hours for assembling the actuator, and it is possible to prevent abnormal noise that occurs when the magnetostrictive element 12e contacts the bobbin 15e.

  Here, the present embodiment describes only the above-described differences with respect to the first embodiment, but only the above-mentioned differences can be changed also in the magnetostrictive actuators of the second to fifth embodiments. And the same function as described above can be added.

(Embodiment 7)
FIG. 7 is a structural cross-sectional view of a magnetostrictive actuator in the seventh embodiment of the present invention. The same parts as those in the first embodiment will be described by omitting the same numbers.

  In the figure, the difference from Embodiments 1 to 6 is that the entire actuator is sealed with resin 24.

  This configuration improves the durability of the actuator itself, including waterproofness and dustproofness, and allows you to enjoy music from any location, as well as voice guidance functions for devices exposed to harsh conditions such as cars and home appliances. Can be added.

  As a material of the resin to be sealed, a resin such as PPS (polyphenylene sulfide) having excellent heat resistance and a certain degree of flexibility is suitable.

  Here, the present embodiment describes only the above-described differences with respect to the first embodiment, but only the above-mentioned differences can be changed also in the magnetostrictive actuators of the second to sixth embodiments. And the same function as described above can be added.

  The magnetostrictive actuator according to the present invention can realize the thinness and excellent linearity of the device itself, so that it can be easily installed in a space-saving space, is useful for acoustic applications such as a panel speaker, and is used in an AV device such as a television. It is also useful as an onboard audio device.

Cross-sectional view of the magnetostrictive actuator according to Embodiment 1 of the present invention Cross-sectional view of a magnetostrictive actuator according to Embodiment 2 of the present invention Sectional drawing of structure of magnetostrictive actuator in Embodiment 3 of the present invention Sectional drawing of structure of magnetostrictive actuator in embodiment 4 of the present invention Cross-sectional view of a magnetostrictive actuator according to Embodiment 5 of the present invention Cross-sectional view of a magnetostrictive actuator according to Embodiment 6 of the present invention Cross-sectional view of the structure of the magnetostrictive actuator according to the seventh embodiment of the present invention Structural sectional view showing an example of a conventional magnetostrictive actuator

Explanation of symbols

12, 12d, 12e Magnetostrictive element 13 Magnet 14 Coil 15, 15e Bobbin 16, 16a, 16b, 16c, 16d Movable part 17, 17a, 17b Upper yoke 18, 18d Lower yoke 19, 19b Adhesive 20 O-ring 21 Vibration transmitting member 22 Movable part recessed part 23 Lower yoke recessed part

Claims (8)

A magnetostrictive element, a movable portion fixed to the upper end of the magnetostrictive element and displaced in accordance with the magnetostrictive displacement of the magnetostrictive element, a bobbin disposed around the magnetostrictive element, a coil wound around the bobbin, A magnet disposed around, a lower yoke disposed so that the lower end of the magnet and the lower end of the magnetostrictive element are coupled, and coupled to the upper end of the magnet and on the outer periphery of the movable unit and substantially flush with the movable unit In the magnetostrictive actuator having a closed magnetic circuit for guiding the magnetic flux of the magnet to the magnetostrictive element, a notch is provided on each of the upper surface of the outer peripheral portion of the movable portion and the upper surface of the inner peripheral portion of the upper yoke. A magnetostrictive actuator in which the notch is filled with an elastic adhesive. 2. The magnetostrictive actuator according to claim 1, wherein a groove is provided on each of an outer peripheral side surface of the movable part and an inner peripheral side surface of the upper yoke, and an elastic O-ring is inserted into the groove. The adhesive is filled in the gap between the outer peripheral side surface of the movable part and the inner peripheral side surface of the upper yoke, and the outer periphery of the movable part or the upper yoke is arranged in order to place this adhesive at a fixed position. The magnetostrictive actuator according to claim 1, wherein a flange that sandwiches the adhesive vertically is formed on either inner circumference. The magnetostrictive actuator according to any one of claims 1 to 3, wherein the magnet has a cylindrical shape and a thickness equal to that of the magnetostrictive element. 4. The magnetostrictive actuator according to claim 1, wherein one end or both ends of the bottom surface of the movable portion and the top surface of the lower yoke are provided with a recess in accordance with the shape of the magnetostrictive element. The magnetostrictive actuator according to any one of claims 1 to 5, wherein a vibration transmitting member having physical properties different from that of the movable member is joined to the tip of the movable portion. The magnetostrictive actuator according to any one of claims 1 to 6, wherein the magnetostrictive element is insert-molded on a resin bobbin. The magnetostrictive actuator according to any one of claims 1 to 7, wherein the entire outer peripheral surface is sealed with a sealing agent such as a resin.

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