JPS6313499

Patent Translate
Powered by EPO and Google
Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JPS6313499
[0001]
FIELD OF THE INVENTION The present invention relates to a high power underwater ultrasonic
transducer with broad band and omnidirectionality. (Prior Art) Conventionally, cylindrical
piezoelectric ceramic transducers operating in a radial mode as shown in FIG. 3 as is well known
are widely used as transducers having nondirectionality. The transducer shown in FIG. 3 has
silver or gold-burned electrodes 31.32 formed on the inner and outer surfaces, and a DC high
electric field is applied using this electrode 31.32 to radially radiate in the thickness direction as
shown by the arrows. It is polarized. This transducer expands and contracts in diameter
uniformly by applying an alternating voltage from the electrical terminals 33. 34, so-called nondirectional acoustic radiation, as indicated by the double arrows with respect to the central axis
in the shear mode. Is done. [Problems to be Solved by the Invention] The conventional cylindrical
piezoelectric ceramic transducer can emit omnidirectional acoustic radiation to the central axis,
but has the following problems. Conventional cylindrical piezoelectric transducers are all made of
piezoelectric ceramics. Piezoelectric ceramics have a density of about 8. Since the sound velocity
related to scratching is 3000 to 3500 m / sec at OX 10 "kg / m", the specific acoustic impedance
(defined by the product of density and sound velocity) is 24 x 10 'to 28 x 10' MKS rayl The
acoustical impedance of the medium, which is the medium, is nearly 20 times as large as that of
water. This results in mismatching of the acoustic impedance between the water and the
transducer, and the bandwidth obtained is limited to 15 percent to at most 30 percent. In order
to obtain a wide band in a cylindrical piezoelectric ceramic transducer, it is necessary to reduce
the mechanical impedance of the transducer in order to improve the impedance matching with
water. It was done exclusively. However, if the thickness of the transducer is reduced, processing
of the piezoelectric ceramic becomes difficult, and the mechanical strength significantly
deteriorates, and high power acoustic radiation becomes impossible. An object of the present
invention is to realize an omnidirectional transducer having a wide band, high efficiency acoustic
04-05-2019
1
radiation characteristics, and capable of high power transmission. SUMMARY OF THE
INVENTION The basic construction of the transducer according to the invention consists of a
piezoceramic cylindrical oscillator and a nonpiezoelectric cylinder which just fits on the outer
surface of the piezoceramic cylinder.
And, the non-piezoelectric cylinder is a material which is light and can have high rigidity with
respect to the central axis direction, for example, a carbon fiber reinforced plastic (c-i'ap) or a
glass fiber reinforced plastic (a-Fap) whose fiber direction is the central axis direction. , Fiber
reinforced metal (FRM), Mg alloy, Al alloy and the like are desirable. The transducer according to
the present invention is integrated with the non-piezoelectric cylinder having a large rigidity with
respect to the central axis direction and the piezoelectric ceramic cylindrical vibrator fitted inside
the non-piezoelectric cylinder, and the scraping operates in the vibration mode. Underwater
ultrasonic transducer. (Operation) In the perspective view of the transducer shown in FIG. 1, a
representative example of the nondirectional high power underwater ultrasonic transducer
according to the present invention is shown in FIG. As a ceramic vibrator, 12 is a nonpiezoelectric cylinder made of a light metal such as, for example, a fiber reinforced composite
material or an Al alloy. The cylinder 12 is just fitted to the outer surface of the piezoelectric
ceramic vibrators 11 and 11 '. The vibrators 11 and 11 'and the non-piezoelectric cylinder 12 are
firmly bonded by an adhesive, and they are integrated with each other so that scratching and
vibration mode transmission are performed as indicated by double arrows. . Incidentally, when
acoustic radiation is actually conducted in water in this transducer according to the present
invention as shown in FIG. 1, both end faces of the cylinder 12 are made of a high strength
material such as Al alloy, steel, FRP by a known technique. The disc is covered with neoprene
rubber. The outer surface of the transducer is covered with an acoustic rubber such as
chloroprene rubber to form a watertight structure. It is essential that the cylinder 12 vibrates
integrally with the cylindrical piezoelectric ceramic vibrator in a scraping vibration mode which
expands and contracts uniformly in the radial direction. Therefore, as a material of the cylinder
12, a composite material having a large elastic modulus in the central axis O-.theta. 'Direction,
that is, 0-FRP or G-FRP in which the fiber direction is arranged in the direction of O-0' is
preferable. This composite material does not contain fibers in the circumferential direction, so
the sound velocity of the plastic that is IJ socks is generally smaller than the sound velocity of the
piezoelectric ceramic. Therefore, with regard to scraping vibration modes, those using O-FRP or
G-FRP according to the present invention can realize a smaller transducer dimension made of a
conventional piezoelectric ceramic cylinder alone, and can be miniaturized. It will be
advantageous if you Also, the transducer according to the present invention has a significantly
improved acoustic impedance matching with water since the effective mass per unit radiation
area is substantially smaller than that of the conventional transducer, and a broadband
transducer can be obtained. Can be realized.
04-05-2019
2
For the same reason, when a hno alloy or a fiber reinforced metal (FRP) having an Aj or Mg
matrix in which the fiber direction is arranged in the central axis direction is used as the material
of the cylinder 12, a conventional cylindrical piezoelectric ceramic transducer is used. In this
case, Aj and Mg have larger sound velocities than the piezoelectric ceramic in comparison with a
transducer using F'RP in the cylinder 12 in this case, so the diameter of the transducer is large.
However, such transducers may be advantageous when incorporating electronic devices within
the transducer to form an enhanced device. (Embodiment 1) An embodiment of a transducer
according to the present invention is shown in FIG. 2 (al is a plan view of the transducer and FIG.
2 (bl is a cross-sectional view). In FIG. 2, 21.21 'is a piezoelectric ceramic cylindrical vibrator, and
the polarization is applied in the thickness direction (radially viewed from the central axis 0-0')
like the vibrator 11.11 'shown in FIG. And, as is well known, in the transverse effect 31 mode, the
wiping takes place. The vibrator 21 '21' is driven in phase as indicated by the arrow. 22 is a 0LFRP cylinder in which carbon fibers are arrayed in the central axis 0-0 ′ direction, and as
described above, since the fiber direction is the central axis direction, bending deformation in the
same direction as o−o ′ On the other hand, the rigidity of the piezoelectric ceramic cylinder is
very high, so that the uniform vibration of the transducer as a whole can vibrate in the vibration
mode in response to the vibration mode of the piezoelectric ceramic vibrator. In this
embodiment, the 0-FRP cylinder 22 shown in FIG. 2 can be obtained by forming a C-FRP plate in
which carbon fibers are arranged in a predetermined direction. In FIG. 2, the piezoelectric
ceramic cylindrical vibrator 21.21 'and the cF 几 P cylinder 22 are bonded using an epoxy
adhesive, and further, the adhesion between the 21.21' and the 22 is not only enhanced but also
the piezoelectric ceramic The outer surface of the cylinder 22 was tightly wound with glass fiber
in order to apply a uniform compressive bias stress to the cylindrical vibrator 21.21 'to increase
the mechanical strength. The same effect can be obtained with carbon fibers and aramid fibers.
The cylindrical vibrator 21.21 'in the present embodiment has the completely same shape, and
has a thickness of 5 M and a height of 3 cIX. The wall thickness of the Q-PRP cylinder is 2 酎.
The overall height of this transducer is 12 cM, and the outer diameter is 1 (1 m). The top and
bottom surfaces of this transducer were covered with a 8 mm thick A) plate, made watertight
with neoprene rubber, and the transmission characteristics were measured in water. The center
frequency was about 9.8 KHz, 3 dB bandwidth 43 % Could be easily obtained.
Also, the acoustic radiation power per unit mass of transducer was significantly higher than that
of the conventional cylindrical piezoelectric ceramic transducer. EXAMPLE 2 A transducer using
an Al alloy as the non-piezoelectric cylinder in FIG. 1 will be described as Example 2 of a
transducer based on the present invention. The piezoelectric ceramic cylindrical vibrators 1'l and
11 'are completely the same as in the first embodiment. Bonding between the vibrator 11.11 'and
the A-alloy cylinder 12 is carried out using an organic adhesive, but since the thermal expansion
coefficient of the Al alloy is about one digit larger than that of the piezoelectric ceramic, the
cylinder made of An alloy is The piezoelectric ceramic vibrators 11 and 11 'may be fitted by
heating 12 to about 100.degree. C. to 150.degree. After fitting, when the temperature is returned
04-05-2019
3
to normal temperature, compressive stress is applied to the vibrator 11, which is extremely
advantageous for high power operation. In the transducer of the present embodiment, the
acoustic velocity of the Al alloy is larger than that of the piezoelectric ceramic, and therefore,
when a transducer of the same size is manufactured, the resonance frequency is higher than that
of the first embodiment. As a specific example, in the case of the same dimensions as the
transducer of Example 1, the resonance frequency is 14.9 kHz. Thus, the transducers of Example
2 are larger in diameter than the conventional cylindrical piezoelectric ceramic transducer and
the transducer shown in Example 1 when compared with transducers of the same frequency.
However, it would be advantageous to implement a transducer system having many functions
that imprisoned the electronics inside the transducer. Also in the transducer shown in the second
embodiment, as in the first embodiment, the mass of the unit radiation area ab can be reduced as
compared with the conventional cylindrical piezoelectric ceramic transducer, so that a wide band
characteristic can be realized. And 3% relative bandwidth of 40% or more can be realized
relatively easily. In FIGS. 1 and 2 of this embodiment, the case of two piezoelectric ceramic
vibrators serving as a drive source of a transducer has been described. However, in the case of
incorporating other numbers, the case of different dimensions It goes without saying that the
effects of the present invention are also noticeable. (Effects of the Invention) As described in
detail above, according to the present invention, it is possible to provide an underwater
ultrasonic transducer excellent in wide band and high power characteristics.
[0002]
Brief description of the drawings
[0003]
1 and 2 show examples of nondirectional cylindrical transducers according to the present
invention, and FIG. 3 shows a conventional cylindrical piezoelectric ceramic transducer.
In the figure, 11.11 'and 21.21' are cylindrical piezoelectric ceramic vibrators, 12.22 is a nonpiezoelectric cylinder, 0-0 'is the central axis of the cylinder, 31.32 is an electrode, 33 ° 34 is It
is an electrical terminal. N1-Figure 1 Figure 2
04-05-2019
4

Download Report