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JP2010258746

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DESCRIPTION JP2010258746
PROBLEM TO BE SOLVED: To provide a small-sized and wide-band underwater acoustic wave
bending-diameter vibration combining type transducer operating in a low frequency range.
SOLUTION: The bending / diameter vibration synthetic transducer of the present invention
comprises an active cylindrical body 2 vibrating at least in a radial direction, a metal cylindrical
body 4 for holding the active cylindrical body, and a disc-shaped metal disk 3. A plurality of diskshaped vibrators to which an active disk 1 is attached by bending and vibrating, and the diskshaped vibrators are disposed opposite to the upper and lower surfaces of the metal cylindrical
body 4, The disk-shaped vibrating body is structured to be coupled by a damper mass 5. The
damper mass 5 is disposed inside the active cylindrical body 2, and the disc-shaped vibrating
body and the metal cylindrical body 4, and the metal cylindrical body 4 and the active cylindrical
body 2 are elastic bodies at respective coupling portions. 6 are connected to each other. [Selected
figure] Figure 1
Flexure-diameter vibration combination transducer
[0001]
The present invention relates to an acoustic wave transducer using an electroacoustic transducer
such as a sonar used in water, and more particularly to a bending-diameter vibration combining
transducer capable of downsizing and broadening the bandwidth in a low frequency range. .
[0002]
Low-frequency acoustic waves are used in acoustic wave transducers that use electroacoustic
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transducers that are used for sonar and marine resource exploration.
Low frequency acoustic waves have a small propagation loss in water.
[0003]
Heretofore, as a transducer of such a low frequency acoustic wave, a transmitter composed of a
bent disk-like vibrator as disclosed in Patent Document 1 is used.
[0004]
FIG. 5 is a trihedral view of a conventional flexural vibration type transmitter.
In FIG. 5, the wave transmitter is formed by fitting and bonding an active disk 21 made of
piezoelectric ceramic into a recess provided at the center of the outer surface of the disk-like
metal disk 22. It consists of a disk-shaped vibrating body 23 of a sheet. Here, the diameter of the
metal disc 22 is larger than the diameter of the active disc 21. The two disc-shaped vibrating
bodies 23 are disposed with their surfaces to which the active disc 21 is not adhered facing each
other, and are joined by bolts 25 at the bonding portion 24 of the peripheral portion, thereby
transmitting the flexural vibration type transmission. Make a bowl.
[0005]
When an alternating current drive voltage is applied between the electrodes formed on both
sides of the active disk 21, the active disk 21 expands and contracts in the radial direction. The
expansion-contraction displacement is expanded to the whole bending vibration displacement by
the disk-shaped vibrating body 23 which made the junction part 24 a support end.
[0006]
The disk-shaped vibrating body 23 is fixed and coupled at the outermost peripheral edge of the
disk-shaped vibrating body in order to generate low frequency acoustic waves. The coupling
point is a fulcrum of the bending vibration of the disc-shaped vibrating body, and the resonant
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frequency of the disc-shaped vibrating body is determined by the distance between the coupling
points. That is, it is only around the specific number of resonances that is determined by the
position of the fulcrum of the flexural vibration that high transmission sound pressure can be
obtained.
[0007]
That is, while the flexural vibration type transmitter has the advantage of being able to realize a
small and lightweight low frequency transmitter, it has the problem that it is difficult to achieve a
wide band.
[0008]
On the other hand, there is a bolt-clamped Langevin transducer as described in Patent Document
2 as a low frequency acoustic wave transducer capable of broadening the bandwidth.
FIG. 6 is a side sectional view showing a general structure of a conventional bolted Langevin
transducer. As shown in FIG. 6, a vibrator 31 having longitudinal vibration in the longitudinal
direction as a basic mode is stacked between the front mass 32 and the rear mass 33, and
compressive stress is applied by tightening them with a bolt 34. A lightweight and rigid metal
material is used for the front mass 32, and a heavy metal material is used for the rear mass 33.
[0009]
The bolt-clamped Langevin type transducer is capable of highly efficient acoustic radiation
characteristics and high power transmission, but on the other hand, it is necessary to increase
the size of the transducer in order to broaden the bandwidth in the low frequency range.
Therefore, the bolt-clamped Langevin type transducer with a wide band has a problem that the
volume increases and the space which can be installed is limited.
[0010]
JP-A-9-200888 JP-A-2000-209690
[0011]
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That is, in the conventional acoustic wave transducer, it has been difficult to simultaneously
achieve downsizing and broadening the bandwidth.
[0012]
Therefore, the problem to be solved by the present invention is to provide a flex-diameter
vibration combined transducer of underwater acoustic wave that can realize both miniaturization
and broadening the bandwidth simultaneously.
[0013]
In order to solve the above problems, according to the present invention, an active cylindrical
body that vibrates at least in a radial direction, a metal cylindrical body that holds the active
cylindrical body, and an active disc that bends and vibrates are bonded to a metal disc. The diskshaped vibrators of a sheet and the damper mass connecting the two disk-shaped vibrators are
provided, and the two disk-shaped vibrators are disposed to be opposed to the upper and lower
surfaces of the metal cylinder. Thus, it is possible to obtain a bending-diameter vibration
combining type transmitter / receiver characterized by the above.
[0014]
Further, the damper mass for coupling the disc-shaped vibrating body is a thread-wound shape
having a disc-shaped flange portion having the same center and a large radius at both ends of the
central mass portion which is a cylinder or a cylinder. A bending-diameter vibration combined
transducer is obtained.
[0015]
Further, a bending-diameter vibration combined transducer is obtained, wherein the bending
vibration of the active disk and the diameter vibration of the active cylindrical body are driven in
opposite phases.
[0016]
In addition, the active disc and the active cylindrical body can be obtained by using a
piezoelectric ceramic as a bending / diameter vibration transducer.
[0017]
In addition, at least one of the active cylindrical body and the metal cylindrical body, and at least
one of the disk-like vibrating body and the active cylindrical body are coupled to each other by
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an elastic body at respective coupling portions. A radial vibration combined transducer is
obtained.
[0018]
According to the bending / diameter vibration combining transducer of the present invention
having the above configuration, when the excitation frequency is in the low frequency range, the
active disc whose resonance frequency is adjusted by the damper mass is bent and oscillated. If
the frequency is in the high frequency range, the active cylinder vibrates in diameter.
By superimposing these vibrations, a broad band transducer can be obtained.
In addition, by adjusting and driving the phase difference between the flexural vibration and the
radial vibration to be 180 degrees, the sound pressure level drop at the non-resonant frequency
of the flexural / radial vibration can be compensated, so the transducer can be miniaturized Can
be realized.
[0019]
3 (A) is a plan view, FIG. 1 (b) is a side view, and FIG. 1 (c) is an AA ′ side, showing an
embodiment of the bending-diameter vibration combining type transducer according to the
present invention. Cross section.
BRIEF DESCRIPTION OF THE DRAWINGS The side sectional view which shows the vibration
mode of the bending-diameter vibration synthetic | combination transducer by this invention.
The finite element method (FEM) analysis figure which compared the frequency-transmission
voltage sensitivity characteristic of the bending-diameter vibration synthetic | combination
transducer by this invention, the conventional transmitter, and a transmitter-receiver.
The figure which compared the volume of the bending-diameter vibration synthetic |
combination transducer by this invention, and the volume of the conventional transmitter and
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transducer.
FIG. 14 is a three-sided view of a flexural vibration type transmitter configured by combining a
conventional disk-shaped vibrator.
The side sectional view of the conventional bolting Langevin type transducer.
[0020]
Hereinafter, embodiments of the present invention will be described with reference to the
drawings.
[0021]
1 (a) is a plan view, FIG. 1 (b) is a side view, and FIG. 1 (c) is an A-A 'side. FIG.
[0022]
As shown in FIG. 1, the flex-diameter vibration composite transducer according to the present
invention comprises an active disk 1, an active cylinder 2, a disk-shaped metal disk 3, a metal
cylinder 4 and a damper mass 5. Configured
The active disk 1 is stacked and firmly bonded so that the center of the active disk 1 coincides
with that of the metal disk 3 to constitute a disk-shaped vibrator.
The disk-shaped vibrating body is installed so as to sandwich the metal cylindrical body 4 and
the damper mass 5 from the upper and lower surfaces.
[0023]
The active cylindrical body 2 is held by holding portions 7 provided at both ends of the metal
cylindrical body 4.
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This structure is obtained by dividing the metal cylindrical body 4 at a half height, inserting the
metal cylindrical body 4 from the upper and lower sides of the active cylindrical body 2 and
firmly bonding the divided surfaces together. An air gap is provided between the active cylinder
2 and the metal cylinder 4 so as not to disturb the vibration of the active cylinder 2. Due to the
air gap, the active cylindrical body 2 and the metal cylindrical body 4 do not contact each other
in the radial direction.
[0024]
The damper mass 5 is in the form of a pincushion having circular disc-like ridges with the same
center and a large radius at both ends of the cylinder or cylinder. In the buttocks, the damper
mass 5 and the disk-shaped vibrating body are firmly bonded on the inner side surface to which
the active disk 1 is not bonded. In order to prevent the vibration of the active disk 1 from being
disturbed, a recessed portion is formed in the bonding portion between the damper mass 5 and
the disk-shaped vibrating body. The recess is formed to be located directly below the active disk
1 when the disk-shaped vibrator is bonded to the metal disk. The resonance frequency of the
disk-shaped vibrator can be adjusted by adjusting the outer diameter of the damper mass 5, that
is, the thickness of the cylindrical portion of the damper mass and the depth of the recess.
[0025]
An elastic body 6 is provided between the active cylindrical body 2 and the holding portion 7. As
the elastic body 6, a lightweight and soft elastic body material such as a cork material or rubber
is used so that the vibration due to the bending vibration of the disk-shaped vibrating body and
the vibration due to the radial vibration of the active cylindrical body 2 does not interfere with
each other.
[0026]
The active disk 1 and the active cylinder 2 are made of a lead zirconate titanate piezoelectric
ceramic, and the metal disk 3 and the metal cylinder 4 are made of a lightweight, mechanically
strong material such as an aluminum alloy 7075. Is desirable. The damper mass is preferably
made of a material having high mechanical strength, such as an aluminum alloy 7075 material or
a stainless steel material.
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[0027]
In addition, the shape of the bending-diameter vibration synthetic transducer according to the
present invention is a disk-shaped vibrating body having an outer diameter of the active disk 1 of
several tens to several hundreds of mmφ, a thickness of the metal disk 3 of 1 to 30 mm. The
thickness of the active cylinder 2 can be set to 1 to 10 mm, the thickness of the active cylinder 2
can be set to 2 to 10 mm, and the height of the active cylinder 2 to 10 to 50 mm, but the total
thickness of the transducer is 50% of the outer diameter It is desirable to be about the following.
For example, the outer diameter of the disk-shaped vibrator is 110 mmφ, the thickness of the
metal disk 22 is 5 mm, the thickness of the active disk 1 is 3 mm, the thickness of the active
cylinder 2 is 5 mm, the height of the active cylinder 2 is It can be 35 mm.
[0028]
Next, the driving principle of the transducer according to the present embodiment will be
described in detail.
[0029]
FIG. 2 is a side sectional view showing the vibration modes of the disk-shaped vibrator and the
active cylindrical body 2 of the bending-diameter vibration synthetic transducer according to the
present invention and the position of the fulcrum thereof.
[0030]
Electrodes are formed on the entire surfaces of the active disk 1 and the active cylinder 2 on the
front and back surfaces.
When an excitation signal is applied at a predetermined frequency between the two electrodes,
as shown in FIG. 2, the active disk 1 generates a vibration that is expanded and contracted in the
radial direction, and the metal disk 3 also adheres to the active disk 1 At this point, the radial
displacement occurs.
On the other hand, the active cylindrical body 2 generates vibrations that expand and contract in
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the radial direction.
[0031]
At this time, since the force of expansion / contraction displacement does not act directly on the
inner side surface of the metal disc 3, the disc-like vibrator bends in the direction perpendicular
to the disc surface with the connecting point with the metal cylinder 4 as a fulcrum. Do. That is,
in the low frequency range, pressure vibration is applied to the surrounding medium by the
bending motion based on the disk surface of the disk-like vibrating body to emit sound waves,
and in the high frequency range, the end point circle of the active cylindrical body 2 By radial
motion based on the circumferential surface, pressure vibration is applied to the surrounding
medium to emit sound waves.
[0032]
Thus, by superposing the characteristics of flexural vibration and radial vibration having
different resonance frequencies, an excitation frequency-voltage sensitivity characteristic having
a sound pressure level within the maximum / minimum sensitivity difference of -6 dB is obtained
in a wider frequency band than before. Be
[0033]
As an example of the present invention, frequency-transmission voltage sensitivity characteristics
in water of a bending-diameter vibration combined transducer according to the present
invention, a conventional bending transmitter, and a conventional bolt-clamped Langevin
transducer. Was analyzed by finite element method (FEM) and the results were compared.
In this analysis, the flexure-diameter vibration composite transducer according to the present
invention has dampers in which the outer diameter of the metal disks 3 and 21 is 110 mm and
the thickness is 5 mm, and the thickness of the active disks 1 and 21 is 3 mm. As for the shape of
the mass, the outer diameter of the central mass portion is 25 mmφ. As a comparative example,
the basic shape of the disk-shaped vibrator is the same, that is, the conventional bending with the
outer diameter of the metal disks 3 and 21 of 110 mmφ, the thickness of 5 mm and the
thickness of the active disks 1 and 21 of 3 mm. The frequency-transmission voltage sensitivity
characteristics in water of the wave type transmitter were analyzed by finite element method
(FEM). As another comparative example, frequency-transmission voltage sensitivity
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characteristics in water of a Langevin transducer having an average outer diameter of 120 mm
and a total length of 300 mm were analyzed by the finite element method (FEM).
[0034]
FIG. 3 shows the frequency-transmission voltage sensitivity characteristics in water of the
bending-diameter vibration synthetic transducer according to the present invention, the
conventional bending transmitter, and the conventional bolt-clamped Langevin transducer. It is
the result of element method (FEM) analysis. From FIG. 3, in the bending-diameter vibration
combining type transducer according to the present invention, the bending vibration of the diskshaped vibrating body whose resonance frequency is adjusted by the damper mass and the
bending vibration have different diameters of the active cylindrical body having different
resonance frequencies. By superimposing the vibration characteristics, wide band characteristics
can be obtained. In FIG. 3, a band improvement of 15.3 times is obtained with a frequency
bandwidth equal to or higher than the constant sound pressure level, as compared with the
conventional transmitter indicated by a thin line.
[0035]
FIG. 4 is a diagram showing the results of comparison of the volume of the bending / diameter
vibration synthetic transducer according to the present invention with the volumes of a
conventional bending transducer and a bolt-clamped Langevin transducer. In this figure, the
volume of the bending-diameter vibration combining transducer according to the present
invention is normalized to one. The thickness ratio and the outer diameter of the active disk
vibrator and the metal disk 3 are the same conditions. It can be seen from FIG. 4 that the volume
of the bending / diameter vibration combining transducer according to the present invention is
1/7 or less of that of the conventional Langevin transducer.
[0036]
From the above, according to the bending-diameter vibration combining transducer according to
the present invention, it is possible to obtain a small-sized, wide-band, bending-diameter vibration
combining transducer operating at low frequency.
[0037]
Incidentally, it goes without saying that the present invention is not limited to the above
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embodiment, and the shape and material of each part can be designed and changed according to
the purpose and required performance.
[0038]
DESCRIPTION OF SYMBOLS 1, 21 Active disk 2 Active cylinder 3 22 Metal disk 4 Metal cylinder
5 Damper mass 6 Elastic body 7 Holding part 23 Disc-like vibrator 24 Joint 25 bolt 31 Vibrator
32 Front mass 33 Rear mass 34 bolt 35 nut 36 air gap
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