JP5281427B2 - Oscillator - Google Patents

Description

  The present invention relates to an oscillator that generates a pressure wave such as a sound wave, and more particularly to an oscillator suitable for use in a deep place in water or soil.

  Conventionally, the use of sound waves for positioning and the like is generally performed in offshore construction and civil engineering (for example, Patent Document 1). Ceramic oscillators are often used as devices that oscillate sound waves in the water, and are widely used for submarine sonar and positioning in offshore construction. Other examples of the sound wave oscillator used in water include an underwater speaker.

JP 2004-151036 A JP-A-2005-192361

  By the way, in recent years, the depth of construction has been increasing, but the external pressure increases as the depth increases in water or soil. Therefore, as shown in FIGS. 6A and 6B, in the structure in which the inside of the diaphragm 61 of the sound wave oscillator 60 is sealed, an external pressure (water pressure) corresponding to the depth is applied to the diaphragm 61. In the case of such a sealed structure, in order to push the diaphragm outward from the inside, a force exceeding the external pressure is required in addition to the rigidity of the diaphragm. Power is needed. Conventionally, there is a sound wave oscillator used in a pool or the like like an underwater speaker, but it can only be used up to a depth of several meters.

  Further, the conventional ceramic oscillator is suitable for generating a high-frequency sound wave such as an ultrasonic wave, but is not suitable for a place where attenuation increases as the frequency of the sound wave increases, such as in the soil. In addition, an electromagnetic force system such as a speaker is suitable for oscillating a sound wave having a relatively low frequency of 4 kHz or less. However, since the mechanism uses the repulsive force of a coil and a permanent magnet, In order to increase the force pushing the diaphragm from the inside to the outside, the sound wave oscillator must be enlarged. However, it is desirable that the acoustic oscillator is as small as possible when it is used by being submerged in the borehole.

  SUMMARY OF THE INVENTION In order to solve the above problems, an object of the present invention is to provide an oscillator that can be used in a deep place in water or soil and can oscillate a low-frequency pressure wave. .

In order to solve the above problems, the present invention comprises a pair of a casing, a diaphragm disposed in the casing, a giant magnetostrictive element and a coil wound around the casing, and vibrates the diaphragm. A giant magnetostrictive actuator, and a control means for driving the pair of giant magnetostrictive actuators, wherein one of the pair of giant magnetostrictive actuators is arranged in a region between the diaphragm and the diaphragm in the casing. Between the casing and the casing , the expansion and contraction direction is arranged to coincide with the vibration direction of the diaphragm , and the other is the diaphragm and the casing in the other region sandwiching the diaphragm in the casing. between, the stretch direction have been arranged to coincide with the vibration direction of the vibrating plate, the vibrating plate is vibrating by the pair of the super magnetostrictive actuator expands and contracts in opposite phase to each other by said control means And a first opening for communicating the one region with the outside of the housing, and a second opening for communicating the other region with the outside of the housing. And an oscillator characterized in that a part is formed.

  With this configuration, since external water and the like can freely enter and exit from the opening into the housing, the pressure applied to both surfaces of the diaphragm is equal to the external pressure. Therefore, even when the oscillator is used at a large depth where the external pressure is large, the diaphragm can vibrate with a force corresponding to the rigidity of the diaphragm itself regardless of the external pressure. Furthermore, by vibrating the diaphragm by a giant magnetostrictive actuator having a large generated stress, a low-frequency pressure wave can be transmitted even at a large depth, and the oscillator can be downsized.

  Further, the pair of giant magnetostrictive actuators may be arranged such that the expansion and contraction directions coincide with the same straight line parallel to the vibration direction of the diaphragm.

  With this configuration, the diaphragm can be more efficiently vibrated by the giant magnetostrictive actuator.

  Further, a plurality of pairs of the giant magnetostrictive actuators may be provided.

  With this configuration, the force for vibrating the diaphragm is increased, and the diaphragm can be vibrated more smoothly.

  The giant magnetostrictive actuator may have the same length in the expansion / contraction direction.

  With this configuration, if a current of opposite phase having the same effective value is supplied to each drive coil of a pair of giant magnetostrictive actuators, the amount of expansion and contraction of the giant magnetostrictive elements becomes equal, so complicated current control is not required. In addition, the diaphragm can be vibrated smoothly.

  The diaphragm is circular, and the total length of the casing in the direction along the vibration direction of the diaphragm is preferably at least twice the diameter of the diaphragm.

  With this configuration, the influence of pressure recirculation can be reduced, and a pressure wave can be efficiently oscillated.

  Moreover, the said housing | casing may be comprised with the metal.

  With this configuration, even when the oscillator is used in a deep place, the possibility of the oscillator itself being destroyed by external pressure is reduced.

  The coil may be surrounded by a rust preventive material.

  With this configuration, the coil can be prevented from being rusted and corroded by water or the like.

  Further, when the oscillator has a plurality of pairs of giant magnetostrictive actuators, the diaphragm is circular, and the plurality of pairs of giant magnetostrictive actuators are arranged at equal intervals on virtual concentric circles having a half radius of the diaphragm. May be.

  With this configuration, since the plurality of giant magnetostrictive actuators can press the entire diaphragm in a well-balanced manner, the possibility that the diaphragm is damaged by being pushed by the giant magnetostrictive actuator is reduced.

  As described above, according to the present invention, it is possible to provide an oscillator that can withstand external pressure at a deep depth, can transmit a low-frequency pressure wave, and can be further downsized. .

1 is a diagram illustrating an oscillator according to a first embodiment. It is a figure showing the electric signal added to the drive coils 13a and 13b. It is a figure explaining the relationship between the length of the side part 11c, and the recirculation | reflux of a pressure. It is a figure which shows the oscillator which concerns on 2nd Embodiment. It is a figure which shows the state by which three pairs of giant magnetostrictive actuators are arrange | positioned at equal intervals on a virtual concentric circle. It is a figure explaining the relationship between an external pressure and the force concerning a diaphragm.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a diagram illustrating an oscillator according to the present embodiment. FIG. 1A is a right side view of the oscillator, and FIG. 1B is a longitudinal sectional view of the oscillator.

  The oscillator according to the present embodiment includes a cylindrical metal casing 11. Here, the opposite ends of the housing 11 are referred to as a right end 11a and a left end 11b, and a cylindrical peripheral surface is referred to as a side surface portion 11c.

  Both the right end 11a and the left end 11b are greatly open. Specifically, cruciform metal support portions 11d and 11e are fixed to the right end 11a and the left end 11b in a posture in which the center of the cruciform is positioned on the axis of the housing 11. The fan-shaped opening 16 is formed between the cross arms of the support portions 11a and 11b. In addition, the opening part is not formed in the side part 11c. Therefore, the inside and the outside of the housing 11 communicate with each other through the openings 16 formed at the right end 11a and the left end 11b, and water and the like can freely enter and exit.

  In addition, as shown in FIG. 1A, the support portions 11d and 11e have a width of each arm portion that is thinner than the thickness of the side surface portion 11c, but as shown in FIG. The thickness of the arm portion is thicker than that of the side surface portion 11c, thereby increasing the opening area of the opening portion 16 without extremely reducing the strength of the support portions 11d and 11e.

  On the other hand, a diaphragm 15 is provided in a substantially central portion in the axial direction inside the housing 11. The diaphragm 15 can freely slide and vibrate along rails 14 a and 14 b provided in the housing 11. The diaphragm 15 is ideally made of a material that is lightweight, has high rigidity, has an appropriate internal loss, and has a high pressure wave propagation speed, like a diaphragm such as a general speaker. Specific examples include wood pulp, synthetic resin materials, metal materials such as titanium and aluminum, and the like.

  Further, as described above, since the outside water and the like can enter and exit the housing 11 through the openings 16 formed at the right end 11a and the left end 11b, they are provided inside the housing 11. The pressure applied to both surfaces of the diaphragm 15 becomes equal to the external pressure, and the diaphragm 15 can vibrate only with a force corresponding to the rigidity of the diaphragm itself, regardless of the external pressure.

  In addition, inside the casing 11, a pair of giant magnetostrictive elements are configured such that the giant magnetostrictive elements 12a and 12b and the drive coils 13a and 13b are wound around the outer peripheral surfaces of the giant magnetostrictive elements 12a and 12b with a gap therebetween so that they can be displaced relative to each other. The actuators are arranged opposite to each other with the diaphragm 15 therebetween so that the displacement direction thereof coincides with the opposing direction of the right end 11a and the left end 11b of the housing 11. The base ends of the giant magnetostrictive elements 12a and 12b are fixed to the center portions of the crosses of the support portions 11d and 11e.

  Further, the casing 11 is preferably made of a material having high rigidity, and the casing itself can withstand external pressure even when the oscillator is used at a deep location by being made of a metal such as iron.

  Incidentally, the oscillator according to the present embodiment is configured using a giant magnetostrictive element as described above. In general, a magnetic material has a property called “magnetostriction” that is deformed when subjected to a magnetic field, but the dimensional change of the magnetic material due to magnetostriction is about 1 to 1 / 1,000,000 (1 to 10 ppm), and the length of the element If the length is 100 m, the displacement due to magnetostriction is about 0.1 to 1 mm.

However, there has been developed a giant magnetostrictive element formed of, for example, terbium, dysprosium, iron, or the like whose displacement due to magnetostriction is 1000 times (1000 ppm) or more that of a conventional magnetic material. In the giant magnetostrictive element, the element length is 1 m and a displacement of several mm is obtained. In addition, since the generated stress of the giant magnetostrictive element is as large as 400 kgf / cm ² , an object weighing 400 kg can be moved with a giant magnetostrictive element having an area of 1 cm square.

  Thus, by configuring the oscillator using a giant magnetostrictive element having a large generated stress, a low-frequency pressure wave can be oscillated and miniaturized even at a large depth with a large external pressure.

  The drive coils 13a and 13b are connected to a drive circuit (not shown), and the drive circuit controls the current flowing through the drive coils 13a and 13b.

  That is, the oscillator according to the present embodiment has a mechanism in which when the current flows through the drive coils 13a and 13b, the giant magnetostrictive elements 12a and 12b are extended and the diaphragm 15 is pressed to vibrate the diaphragm 15. More specifically, the current flowing through the drive coils 13a and 13b is driven so that when one of the giant magnetostrictive elements 12a and 12b is extended, the other contracts, and when the other is extended, the other contracts. By controlling with a circuit, the diaphragm 15 is alternately pushed in the left-right direction by the giant magnetostrictive elements 12a and 12b and vibrates.

  In addition, the giant magnetostrictive elements 12a and 12b are arranged such that a minute gap is left between the tip of each of the giant magnetostrictive elements 12a and 12b and the diaphragm 15 in a state where no current flows through the drive coils 13a and 13b. Specifically, when the giant magnetostrictive elements 12a and 12b are extended by applying a bias current that is an intermediate current when the diaphragm 15 is vibrated to the drive coils 13a and 13b, the tips of the giant magnetostrictive elements 12a and 12b vibrate. It arrange | positions so that a board may be touched. That is, when no current flows through the drive coils 13a and 13b, the tips of the giant magnetostrictive elements 12a and 12b are not in contact with the diaphragm 15.

  Furthermore, the vibration method of the diaphragm 15 will be described in detail with reference to FIG. FIG. 2A is a diagram illustrating an electrical signal applied to the drive coil 13a, and FIG. 2B is a diagram illustrating an electrical signal applied to the drive coil 13b.

  The giant magnetostrictive elements 12a and 12b have the property of extending regardless of the polarity of the magnetic field when a magnetic field is applied. That is, as shown in FIGS. 2 (a) and 2 (b), when an electric signal is applied to the drive coils 13a and 13b, the normal length is a state in which a predetermined length is extended by the bias current, It expands when an electrical signal greater than the current is applied (shaded area), and shortens when an electrical signal less than the bias current is applied.

  The drive coils 13a and 13b are applied with electrical signals having opposite phases with a bias current as a center. As a result, the diaphragm 15 and the giant magnetostrictive elements 12a and 12b contract one when the other is extended, and the other contracts when the other is extended. Therefore, the diaphragm 15 is always in close contact with each other. Will be pressed alternately from left and right. As a result, the diaphragm 15 vibrates around the bias position (position when the bias current is passed through the drive coils 13a and 13b).

  However, since the diaphragm 15 emits vibrations in opposite phases, as shown in FIG. 3A, when the length L1 of the cylindrical side surface portion 11c of the housing 11 is short, positive and negative pressure is applied. The outputs of each other may cancel each other out (pressure is recirculated), and the pressure wave output of the oscillator as a whole may decrease. Accordingly, the length L1 of the side surface portion 11c needs to be long enough so that the pressure is not recirculated. This appropriate length is calculated from the relationship between the properties of the medium around the oscillator and the size of the bottom surface of the housing. For example, if the length is about twice the diameter of the diaphragm 15, the effect of pressure reflux Is negligible, and a pressure wave can be efficiently emitted to the outside.

  Further, as shown in FIG. 3 (b), only the side surface portion 11c of the housing 11 protrudes from the periphery of the right end 11a (or the left end 11b) without increasing the length between the right end 11a and the left end 11b. If so, the reflux of pressure can be reduced.

  As described above, when the diaphragm 15 is provided at a position equidistant from the right end 11a and the left end 11b, the super magnetostrictive elements 12a and 12b have the same length in the expansion / contraction direction, and both magnetostrictions are the same. This is also preferable because the amount of displacement due to the above becomes equal, which makes it easy to control the current flowing in the drive coils 13a and 13b described later. However, this configuration is not essential, and the diaphragm 15 may be provided at a position close to either the right end 11a or the left end 11b. In this case, the lengths of the giant magnetostrictive elements 12a and 12b are different, and the amount of displacement due to the magnetostriction is also different, but the currents flowing through the drive coils 13a and 13b are adjusted to change the displacement of both giant magnetostrictive elements. What is necessary is just to control with a drive circuit so that quantity may become the same quantity.

  In addition, since the oscillator according to the present embodiment is assumed to be used in water or soil, the casing 11, the giant magnetostrictive elements 12a and 12b, the drive coils 13a and 13b, and the diaphragm 15 It is desirable that waterproofing or water-proofing is applied. Further, the periphery of the drive coils 13a and 13b may be surrounded by a rust preventive material such as oil. Thereby, even if an oscillator is used in seawater etc., it can prevent that the drive coil 13a etc. rust and corrode.

  As described above, unlike the conventional pressure wave oscillator, the oscillator according to the present embodiment is provided with the opening 16 so that external water and the like can freely enter and exit from the inside of the casing 11. Is equal to the external pressure, and the diaphragm 15 can vibrate with a force corresponding to the rigidity of the diaphragm itself regardless of the external pressure. In addition, since the diaphragm 15 is vibrated by the giant magnetostrictive actuator, a pressure wave can be oscillated even at a large depth where the external pressure is large, and the size of the oscillator can be reduced.

(Second Embodiment)
FIG. 4 is a diagram illustrating the oscillator according to the present embodiment. FIG. 4A is a right side view of the oscillator, and FIG. 4B is a longitudinal sectional view when the oscillator is cut along an AA ′ plane.

  The oscillator according to the present embodiment has a cylindrical metal casing 41 as in the oscillator according to the first embodiment. Here, the opposite ends of the housing 41 are referred to as a right end 41a and a left end 41b, and a cylindrical peripheral surface is referred to as a side surface portion 41c.

  Both the right end 41a and the left end 41b are greatly open. Specifically, support portions 41d, 41f, and 41h are formed at the right end 41a integrally with the side surface portion 41c at the peripheral end of the right end 41a, and support portions 41e, 41g, and 41i are formed at the left end 41b. The side end 41c is formed integrally with the peripheral end of the left end 41b. In addition, at the right end 41a and the left end 41b, portions other than the support portion 41d and the like are openings 46. In addition, the opening part is not formed in the side part 41c. Therefore, the inside and the outside of the housing 41 communicate with each other through the openings 46 formed at the right end 41a and the left end 41b, and water and the like can freely enter and exit.

  As shown in FIG. 4B, the thickness of the support portion 41d and the like is thicker than that of the side surface portion 41c, so that the opening of the opening portion 46 can be formed without significantly reducing the strength of the support portion 41d and the like. The area is increased.

  On the other hand, a diaphragm 45 is provided at a substantially central portion in the axial direction inside the housing 41. The diaphragm 45 can freely slide and vibrate along rails 44 a and 44 b provided in the housing 41. The diaphragm 45 is ideally made of a material that is lightweight, has high rigidity, has an appropriate internal loss, and has a high propagation velocity of pressure waves, like a diaphragm such as a general speaker. Specific examples include wood pulp, synthetic resin materials, metal materials such as titanium and aluminum, and the like.

  Further, as described above, since the outside water and the like can enter and exit from the inside of the casing 41 through the openings 46 formed at the right end 41a and the left end 41b, they are provided inside the casing 41. The pressure applied to both surfaces of the diaphragm 45 becomes equal to the external pressure, and the diaphragm 45 can vibrate only with a force corresponding to the rigidity of the diaphragm itself, regardless of the external pressure.

  Also, inside the casing 41, the giant magnetostrictive elements 42a, 42b, 42c, 42d, 42e, 42f, and the drive coils 43a, 43b, 43c, 43d, 43e, 43f can be displaced relative to each other on their outer peripheral surfaces. Three pairs of giant magnetostrictive actuators that are wound around each other are opposed to each other with the diaphragm 45 interposed therebetween so that the displacement direction thereof coincides with the opposing direction of the right end 41a and the left end 41b of the housing 41. Are arranged. The base ends of the giant magnetostrictive elements 42a, 42b, 42c, 42d, 42e, and 42f are fixed to the support portions 41d, 41e, 41f, 41g, 41h, and 41i, respectively.

  Note that the drive coil 43a and the like are connected to a drive circuit (not shown), and the current applied to the drive coil 43a and the like is controlled by this drive circuit.

  That is, the basic configuration and operation method of the oscillator according to this embodiment is the same as that of the oscillator according to the first embodiment, but a giant magnetostrictive actuator constituted by the giant magnetostrictive element 42a and the drive coil 43a and the like. The feature is that three pairs are provided. Thereby, the force which presses the diaphragm 45 from both surfaces becomes strong, and a diaphragm can be vibrated more smoothly.

  As shown in FIG. 5, the three pairs of giant magnetostrictive actuators may be arranged at equal intervals on virtual concentric circles 51 having a radius that is half the radius of diaphragm 45 that is a disc. As a result, when the three pairs of giant magnetostrictive actuators press the diaphragm 45, the entire diaphragm can be pushed in a well-balanced manner, so that the possibility of breakage due to the diaphragm 45 being pushed by the giant magnetostrictive actuator is reduced. .

  In the present embodiment, the case where three pairs of giant magnetostrictive actuators are used is shown, but two pairs of giant magnetostrictive actuators may be used, or more giant magnetostrictive actuators may be used.

  As described above, the oscillator according to the present embodiment can oscillate a pressure wave even when a large external pressure is applied to the oscillator and can be downsized. By having it, the force which vibrates the diaphragm 45 becomes strong, and a diaphragm can be vibrated more smoothly.

(Other embodiments)
In the above-described embodiment, the case where the opening 16 and the like are provided at the right end 11a and the left end 11b is shown. As long as it is within the region and the region on the left end 11b or the like side, it may be formed on the side surface portion 11c, for example.

  Further, in the above embodiment, the openings 16 and the like are formed one by one in the region on the right end 11a side and the region on the left end 11b side with the diaphragm 15 and the like interposed therebetween. May be.

  In the above embodiment, the opposing giant magnetostrictive actuators are arranged on the same straight line parallel to the vibration direction of the diaphragm 15 or the like, but it is not always necessary to be configured in this way. In particular, when using three pairs of giant magnetostrictive actuators as in the second embodiment, for example, opposing giant magnetostrictive actuators may be arranged at different positions on the circumference of the virtual concentric circle 51, respectively. . As the number of giant magnetostrictive actuators that press the diaphragm 45 increases, the entire diaphragm is pushed evenly. Therefore, even if the position of the opposing giant magnetostrictive actuator is shifted, the influence on the vibration of the diaphragm 15 is small. is there.

  In the above embodiment, the vibration plate 15 and the like can freely slide and vibrate along the rails 14a and 14b provided in the housing 11 and the like. It may be a thinner one (vibration membrane), and the circumference of the diaphragm 15 or the like may be fixed to the inner circumferential surface of the housing 11 or the like.

  Further, in the above-described embodiment, the case where the casing 11 of the oscillator or the like has a cylindrical shape is shown, but other shapes may be used. For example, the shape may be a triangular prism, a quadrangular prism, or the like. Further, the shape of the diaphragm 15 and the like is also shown in the above embodiment as being circular, but may be other shapes. For example, the shape may be a triangle, a quadrangle, or the like.

(Summary)
As described above, according to the present invention, as described above, according to the present invention, it is possible to withstand a large depth of external pressure and to transmit a low-frequency pressure wave, and further downsizing. An oscillator that can be provided can be provided.

DESCRIPTION OF SYMBOLS 11 Housing | casing 12 Giant magnetostrictive element 13 Electromagnetic coil 14 Disc spring 15 Driving knob 11 Housing | casing 11a Right end 11b Left end 11c Side surface part 11d, 11e Support part 12a, 12b Giant magnetostrictive element 13a, 13b Driving coil 14a, 14b Rail 15 Diaphragm 16 Opening 41 Housing 41a Right end 41b Left end 41c Side surface 41d, 41e Supporting part 42a, 42b, 42c, 42d, 42e, 42f Giant magnetostrictive element 43a, 43b, 43c, 43d, 43e, 43f Drive coil 44a, 44b Rail 45 Vibration Plate 46 Opening 51 Virtual concentric circle 60 Sound wave oscillator 61 Vibration plate

Claims (8)

A housing,
A diaphragm disposed in the housing;
A pair of giant magnetostrictive actuators comprising a giant magnetostrictive element and a coil wound around the element, and for vibrating the diaphragm;
Control means for driving the pair of giant magnetostrictive actuators,
One of the pair of giant magnetostrictive actuators has an expansion / contraction direction that coincides with a vibration direction of the diaphragm between the diaphragm and the casing in one region sandwiching the diaphragm in the casing. The other is arranged between the diaphragm and the casing in the other region sandwiching the diaphragm in the casing so that the expansion and contraction direction thereof coincides with the vibration direction of the diaphragm. The diaphragm is vibrated by extending and contracting the pair of giant magnetostrictive actuators in opposite phases by the control means,
The housing is formed with a first opening for communicating the one region with the outside of the housing, and a second opening for communicating the other region with the outside of the housing. An oscillator characterized by having   2. The oscillator according to claim 1, wherein the pair of giant magnetostrictive actuators are arranged such that their expansion and contraction directions coincide with the same straight line parallel to the vibration direction of the diaphragm.   The oscillator according to claim 1 or 2, comprising a plurality of pairs of the pair of giant magnetostrictive actuators.   The oscillator according to any one of claims 1 to 3, wherein the pair of giant magnetostrictive actuators have the same length in the expansion and contraction direction. The diaphragm is circular,
5. The oscillator according to claim 1, wherein a total length of the casing in a direction along a vibration direction of the diaphragm is at least twice the diameter of the diaphragm.   The oscillator according to claim 1, wherein the housing is made of metal.   The oscillator according to claim 1, wherein the coil is surrounded by a rust preventive material. The diaphragm is circular,
4. The oscillator according to claim 3, wherein the plurality of pairs of giant magnetostrictive actuators are arranged at equal intervals on virtual concentric circles having a radius that is half of the diaphragm.

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