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JPS60109399

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DESCRIPTION JPS60109399
[0001]
The present invention relates to a bolted lung-pan vibrator used in an underwater ultrasonic
transducer, and it is an object of the present invention to reduce the weight and simultaneously
increase the power of the bolted lung-pan vibrator. Conventionally, as shown in FIG. 1, a boltclamped Langevin vibrator is a ring-shaped piezoelectric member disposed between a front mass
11.7 o 7 mass 11 and a rear mass 13 made of a high rigidity material such as aluminum alloy,
titanium alloy or steel. Ceramics 12, rear mast 13 made of high rigidity material like front mast 1
and ring shaped piezoelectric ceramics 121 Bolt made of high tensile alloy such as Or-M, o steel
with function to add pressure resistant material 14 , And has a large feature that high power
drive is possible. Here, in the ring-shaped piezoelectric ceramic, the longitudinal effect
longitudinal vibration mode (33 mode) in which an electromechanical coupling coefficient much
larger than the transverse effect longitudinal vibration mode (31 mode) is obtained is used.
Adjacent ring-shaped piezoelectric ceramics are polarized in opposite directions to each other as
indicated by arrows in the figure, and electrically connected in parallel to each other to achieve
matching with the word amplifier. Also, in general, ceramics are weak against tensile stress t
compared to compressive stress, so static bias compressive stress is applied in advance by bolt
14 and grain 5, and a structure that sufficiently withstands use even in high power temporary It
has become. In the port-clamped Langevin oscillator with such a structure, a half-wave resonant
mode is used as is well known, and there are vibration nodes in the piezoelectric ceramic 8 and
7112 parts, and the stress is in the piezoelectric ceramic 12 and bolt 14 parts. Work intensively
in The bolted Langevin oscillators used in the above-mentioned underwater ultrasonic
transducers are usually arranged in large numbers in order to obtain a desired directivity, and
such an array of large number of arrayed oscillators is inevitably large. In recent years, a
reduction in size and weight of a bolt-clamped lange-pan vibrator has been strongly demanded in
order to produce an extremely heavy product. However, conventionally, a vibrator shape adapted
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to high power and at the same time miniaturization has not been obtained. The present invention
has been made to achieve high power and simultaneous weight reduction of a bolt-clamped lunge
pan vibrator. The object of the present invention is to provide a vibrator having an optimum
shape which achieves both the reduction in weight and the increase in power.
In the present invention, a half-wave resonant bolt-clamped Langevin oscillator comprising a
front mass portion, a piezoelectric ceramic portion, and a rear mass portion l): a sound la
radiation cross section 槓 of a J mass portion, , The cross-sectional area of the piezoelectric
ceramic portion 82. Cross section of bolt part S8, U of rear mass part? The cross-sectional area S
of the piezoelectric ceramic portion is S, where L is 84, the length of the front mass portion is 11,
and the length from the # end of the front mass portion to the vibration node is lo. Then, the
cross-sectional area S3 of the bolt portion is set to be considerably small, and the front half
portion from the bottom echo emission end of the front mass portion to the point a11 is
considered, 0.03 ≦ 8. / S, ≦ 0.1.0.1 <lt / lo ≦ 0.3, and it is characterized in that S 2 / S 4> 0.2 in
view of the other half from the vibration node to the rear mass end It is a bolt-clamped lung-pan
vibrator. In order to obtain a bolt-clamped Langevin oscillator having an optimum shape as an
object of the present invention, it is considered to be divided into a quarter wavelength part of
the front half from the front mass to the vibration node and a second half from the vibration
node to rear mass. First, consider the mechanical system of bolt-clamped run-di-pan oscillator
with the equivalent composite transmission line, and here, when it is operated in water, with the
standardized oscillator mass as a standard of weight reduction. From the trade-off with the stress
applied to the bolt and the piezoelectric ceramic part, the vibrator shape excellent in the
mechanical strength at the same time as the weight reduction is clarified. Furthermore, the
analysis including the electrical system is performed, the relationship between the capacity ratio
closely related to the electromechanical conversion efficiency (the energy conversion efficiency is
higher as the capacity ratio is smaller) and the shape of the vibrator is shown, and finally the
mechanical system (! : Find the optimum vibrator shape that can be reduced in weight and at the
same time high power, considering both electrical systems. In order to obtain a lightweight and
high-power vibrator, as shown in FIG. 2, first, theoretical examination is carried out on the
vibrator cow section from the sound emitting edge to the vibration node. In FIG. 2, 11 is a front
mass portion, 12 is a piezoelectric ceramic portion, 14 is a bolt portion, 11 is a length of the
front mass 12 is a length of the piezoelectric ceramic portion = length of a bolt portion), 1 o (− /
□ ten lit) indicates an effective quarter wavelength. The equivalent lateral transmission line of
the half-section model shown in FIG. 2 is shown in FIG. In FIG. 3, the density of the first portion (i
= 1.2.3) is ρ1, the longitudinal wave velocity is C1, the cross section is S1, and the phase
constant is βi (= ω / C1, ω; angular frequency, ω = 2πf), Z characteristic impedance density.
1 (= 1 1 Ci), Z the characteristic impedance. Let i ′ ′ ′ ′ zoi ′ ′ i), and R 1 is an acoustic
radiation impedance expressed by the following equation. R, a = 。. cos, (1,) but ;; density of
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water co; speed of sound of water Sl; radiation cross section but effective longitudinal wave
velocity with respect to the piezoelectric ceramic portion is 02e (= T four) 5; 1.3331 ': electric
field 1 As the elastic compliance at a fixed time, the effective phase constant, the characteristic
impedance density, and the characteristic impedance are respectively β2e′′02e, Z. The
resonance relationship of the 02e-equivalent composite transmission line in FIG. 3 is obtained by
setting the sum of the impedances of the respective transmission lines viewed from 1-1 'to zero.
(It is assumed that I-La = 0 because it is the resonance frequency of the oscillator itself), that is, Z
6 s tan (βs 4) -Z 62 e cot (β 2 J 2) -Zo 3 cot β, A, OO (2) where the ratio of the characteristic
impedance As K = Z o 2,4 / C. 1 (3−2eK = Zo3 / Zol (4) 3) Further, when standard constants α!
And α2 are introduced with a quarter wavelength as a standard, the equation (2) becomes as
follows. If the material of each part of the vibrator is determined and then the cross-sectional
area ratios S, / S, S, / S are given, the equation (8) becomes an equation consisting of two
variables α1 and α. That is, when α1 is given, α in accordance with α1 is reduced, and the
dimensional ratio l, / l. And the resonance frequency. The total mass M of the oscillator of the
half section shown in FIG. 2 is given by M = .rho.I.sup.z ts, 10 @ 2 .rho.2 A'lj St + .rho. Since the
resonance frequency and the length are in inverse proportion to each other, a standard of the
lightening optimum shape per unit acoustic radiation area normalized by the resonance
frequency is given by M f r / S. Further, it is normalized by the characteristic acoustic impedance
density 2 ° 2 (ρtc 2 e) of the piezoelectric ceramic part, and the normalized oscillator mass M.
Is given by. Prior to the calculation, Table 1 shows the density and longitudinal wave velocity of
the material generally used in each part of the bolted lung-pan vibrator. Using the materials
shown in Table 1 Table 1, as an example, the ratio of the bolt cross-sectional area to the acoustic
emission surface tJ tc.8. When the piezoelectric ceramic cross section CRSt / S with respect to the
acoustic emission area is set as a parameter, the ratio of the length of the front mass to the
effective quarter wavelength I31 / lo and the oscillation are constant. The relationship between
the normalized mass Mn of the first half of the child is shown in FIG.
As shown in FIG. 4, when 't / 16 is in the range of 0 to 04, Mn gradually increases with the
increase of l, / llo, but when l, llo is thicker than 0.3 (when the rice is rapid It can be seen that it
is better to reduce St / S + and 4 / llo in order to make the oscillator at. The cross-sectional area S
of the bolt is usually designed to be considerably smaller than the cross-section (It St) of the
piezoelectric ceramic portion as shown in FIG. This is due to the negative effect that the
electromechanical conversion efficiency decreases as Ss approaches S. Ssが8. In a much
smaller range, Mn is 8. / S, T hardly affected. At this time, if the cross-sectional areas Sa and sB of
the piezoelectric ceramic portion and the bolt portion are set smaller than the acoustic radiation
area S1, the weight can be reduced accordingly, but stress is concentrated on the bolt portion
and the piezoelectric ceramic portion. It is surmised that it is difficult to reduce the weight with
high power taken into account by reducing the simple cross section S 2 and S 3. Then, it is added
to the piezoelectric ceramic part and bolt part of the bolt-clamped Langevin oscillator.
Theoretical study on vibrational stress. In general, when transmitting water in water, the stress
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acting inside the vibrator is different from the vibration state in the air, and a reaction due to the
acoustic radiation impedance of water is further added at the end face of the liver echo radiation.
Here, when the acoustic radiation surface is resonated at a unit speed (1 m / see) under water
load, the stress which is ming on the piezoelectric ceramic part and the bolt part is obtained from
the other circuit shown in FIG. Calculate motion shape dependence. The stressed portion of the
piezoelectric ceramic portion and the portion receiving the largest stress is the vibration node
shown in FIG. 3B, and let the stress at this point be Tlm. Similar to FIG. 4, FIG. 5 shows the
relationship between IT and rrll with respect to the dimensional ratio /// jo when using the
parameter St / S 1 when SB / Ss = 0.006 constant. It can be seen that ITpml increases as A, / Ito
increases as S, / S decreases. Next, the relationship between the stress acting on the bolt portion
and the shape of the vibrator is determined in the same manner. The vibration stress acting on
the bolt at the junction with the front mass is Tbo, and the vibration stress acting on the bolt at
the vibration node is Tbm. The relationship between ITbol and lTbm1 and the shape of the
vibrator is shown in the same manner as in FIG. In FIG. 6, the solid line shows the characteristics
of ITb, and the dotted line shows the characteristics of lTbm1.
Although there is no significant difference between ITboI and lTbmI at /lQ>0.2, ITbcl <lTbm1 and
i, 1TboI and lTbm1 increase as / 10 increases, and at the same time ITbol and lTbm closely
approach. しかし、l。 When /2o<0.1, l and / 11o decrease, that is, as the length of the front
mass becomes shorter, the behavior is such that the inverse scale 1Tl) CI, l ']' l) m + increases.
This is because when the front mass becomes extremely thin, stress concentrates on the joint
between the bolt and the front mass due to the reaction of the acoustic radiation impedance of
water. The weakest part of the bolted Langevin oscillator is the connection between the front
mass and the bolt and the ceramic center. In order to increase the power of the vibrator at the
same time as reducing the weight of the vibrator, it is desirable that the vibrator be configured
such that stress does not concentrate on a portion where mechanical strength is weak at a
constant vibration velocity at the sound emitting edge. So we give the figure of Merit about the
quality of the oscillator. This is closely related to the maximum acoustic power that can be taken
out per unit mass of the vibrator, and the shape of the vibrator is better as the FMMm is larger.
Next, the capacitance ratio γ, which is a measure of the electromechanical conversion efficiency,
is equal to that of Martin's other circuit (G, E, Maytin: Vibrations' of 0axially 8 segmented ).
LongitudinallyPo1arizedFeroelectricTubes 1l
JournalofAcoust、Soc、AJn、Vol。 It can be easily obtained from the
relationship of the resonant anti-resonance frequency by representing by 36, 8 pp, 1496-1506,
(1964)). The smaller the value of γ, the better the electromechanical conversion efficiency.
Therefore, the figure of Merit FMm for weight reduction including the electrical system of the
quarter wave portion from the acoustic emission end is expressed by the following equation Be
FMM m F'M =-(2 Mm characteristics when using the materials shown in Table 1 as materials of
respective parts of the 12 [gamma] vibrator and assuming the electromechanical coupling
coefficient k ss -50 of the piezoelectric ceramic are shown in FIG. Here, it is well known that
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when the front mass becomes thin and / 13 o becomes less than or equal to 01, the front mass
self-excites flexural vibration and the pure piston movement is no longer possible, so that the
acoustic radiation efficiency decreases. .
Therefore, in FIG. 7, the range of L / ljo> 0.1 is worth practical use. When S2 / S1 is extremely
small and smaller than 0.03, it is the case that FMM is Masuda dog (7, but the capacity ratio γ
becomes large, and as a result, FMm decreases. Indeed, for the front half of the sound of the front
mass + W radiation end to the front half of the one-wavelength part, if the cross-sectional area S,
/ S becomes smaller than 0.03, against the static stress when the bolt is tightened Since the
strength in the radial direction of the piezoelectric ceramic and the cling is not sufficiently
increased, it is not preferable for practical use. In FIG. 7, when using the A7 alloy for the
piezoelectric ceramic and front mass with k □ = 0.50, the value of FMln does not achieve the
desirable value of 1.5 × LO′♂ / N in the conventional vibrator shape. 9). In addition, S2 / S,
about 0.12 or more or A. When / lo is larger than 0.3, F M, n is 1.5 × 1. It becomes difficult to
exceed F7 rl / N. That is, the shape of the vibrator for increasing the FMm, in other words, the
shape of the light-weight and high-power vibrator has a cross-sectional injection of 0.03 ≦ 8. / 8.
≦ o, i, 0.1 for the length, IIts, / l! It is found that o 〈0.30. Next, FIG. 8 shows the 1 Mm
characteristics when a carbon fiber reinforced resin (0-FRP) having a rigidity equal to or higher
than that of an AA gold alloy and smaller in density than the A6 alloy is used as a front mass
material. From Fig. 8 to · Fig. 7 ′ ′ Generally, it is larger than the FMm value when using the
alloy shown in 7 ′ ′ 7 ′ ′ ′, but the trend of the micro-trench shape to increase FMIn is the
front mass material It is clear that although they differ, they are exactly the same. Next, with
regard to a quarter wavelength portion of the second half from the vibration node to the rear
mass, the transducer shape to be reduced in weight and / X power will be described. The
physical model of the transducer section from the perturbation node to the rear mass end of the
bolt-clamped Langevin oscillator shown in FIG. 1 is shown in FIG. In FIG. 9, reference numerals
12 'and 14' denote a piezoelectric ceramic portion and a bolt portion, respectively, and 13
denotes a rear mass portion. Ito 'is an effective quarter wavelength, 1% is the length of the
piezoelectric ceramic portion (-volt portion), and 14 is the length of the rear mass portion. 12
'and 1.4' are mechanically continuous with the piezoelectric ceramic portion and the bolt portion
14 from the front mass to the 4th node shown in FIG. 2 mechanically, and the materials of 12
and 12 ', 14 and The materials of 14 'are both identical, and the cross-sectional areas of the 12
and 12' sections are equal.
Here, in order to find the shape of a clean oscillator, the oscillator is divided into two parts, the
front half and the rear half, but in reality l and 12 'and 12', 1.4 and 14 'are In the integrated case,
when the sound emitting end of the front mass vibrates at a certain speed, the front and back
half of the transducer have the same finger contact, and the stress acting on this is of course both
equal. At this vibration node, maximum stress occurs unless the length of the front mass is
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extremely short. The vibrational stresses T1m and Tbm in this portion are already satisfied. The
density of the rear mass portion is ρ4, the sound speed is 04, and the cross-sectional area is 84.
■ Characteristic acoustic impedance Z of the part. 4. The phase constant .beta.4 is Zn2 = 1.sup.4
C484 = ZO484 ([31.beta., 13. =. Omega.A, /C4=(.pi./2).alpha.4u4). The total mass M 'of the
second half of the vibrator shown in FIG. The characteristic acoustic impedance Z of the
piezoelectric ceramic part, since the resonance frequency and the length are in inverse
proportion to the mass of the rear half of the vibrator, and the cross-sectional shape of the
piezoelectric ceramic part is equal in the front half and the rear half. It can be normalized by 2e.
Assuming that the normalized mass is M ', M'o is given by one α', = βze "2 (16). Since the stress
at the vibration node is determined in the first half of the vibrator, the normalized mass M'0 is
smaller in the second half of the vibrator, and the capacitance ratio γ 'of the second half of the
vibrator is also small. The figure of Merit is better. The latter half θ) Figure of Merit FM 'is given
by the following equation. Fig. 10 and Fig. 11 show the 1M7m and its related oscillator shapedependent characteristics when using AA gold alloy and stainless steel (ρ = 7.91113 '/ nl', c =
5.00m / 5ee) as the rear mass. It is shown in the figure. いずれもS。 Also, FM '□ with a large /
84 tends to be thick (when it becomes 020 or more, it tends to saturate. For the rear half 174
wavelength part from the vibration node to the rear mass end, in order to obtain light weight and
required sound pressure, the value of FM ′ □ is required to be 0.8 or more. In order to
achieve this, it is extremely difficult to make the value of FM / □ 0.8 or more if <St / S4 is about
0.15, as apparent from FIG. 11, and S, / S, 020 is required. Also, FM 'tends to increase as S and /
S increase, but when S3 / S4 is 0.70 or more, the bolt 14 as shown in FIG. It becomes difficult
and loses practicality.
As described above, the theoretically considered figure of Merit FMm, FM'm4 is larger, and the
larger the FM m, the better the electro-acoustic conversion efficiency-the more excellent the
piezoelectric ceramic and the vibration stress applied to the bolt portion, the acoustic radiation
end face per vibrator mass Vibration velocity U can be increased. The vibration velocity U is
proportional to the square root of the acoustic radiation energy Pa. In addition, as FM'In is larger,
the conversion efficiency to electroacoustics is more excellent, and a lightweight copying motor
can be realized. That is, if the acoustic radiation cross-sectional area SI and the resonance
frequency fr are the same, FMm and FM'- are large keys, but the figure of Merit but Mt; the value
of the vibrator total mass can be increased. In recent years, the sounding distance of sonar
transducers has increased, and at the same time, weight reduction and high power have been
required. As for the l0 KH band oscillator, the square root of the # echo output per fifth, that is,
the value of FMm of the ρ 0 expression, is required to be Ioo, 7i / or more. The following
embodiments of the present invention have a resonance frequency in the 10KH band, and also
have the same radiation surface disturbance and have different shapes A, B, 0, D4 as shown in
Table 2 The bolt-clamped lange-pan oscillator for the underwater ultrasonic wave transmitter
was made as an experiment, and the evaluation of the figure of Meri was carried out. The
oscillators A, B, 0,. D is a zircon-lead titanate-based ceramic having 0.50% as piezoelectric
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ceramics, AA gold alloy as front mass material, stainless steel as rear mass material, bolt, Or-M as
natto material. I use steel. The values of FMm and FMI □ calculated from the vibrators having
the shapes A, B, 0, and D shown in Table 1 and Table 2 are plotted in FIGS. Figure: Meri t (1) As
for the evaluation, the transducer is driven electrically, and the relationship between the acoustic
output power and the electrical input power is calculated, and the linearity of the acoustic output
power against the electrical input power is abrupt Assuming that the sound output power at the
time of deterioration was Pa, then the FM was calculated according to the equation (d). ル 2 2 2
tr 第 第 3 表 振動 子 器 A 振動 子 1i′′M ′> 0.80.8, FM は 小, 振動 子 子 B は F M> 1.5 X 1ff
7rtl '/ Nm m However, the FM '□ is small 6 and the oscillator 0 is small for both FNm and FM'
□. As for the vibrator, both FMm and FM / □ are designed to be large. It is apparent that the
vibrators with large values of FMm, FM and I □ shown in FIG. 7 and FIG. 1 are, in fact, lightweight vibrators with large output sound pressure.
In particular, it is understood that a vibrator having a large value of both FMm and FMlm is
lightweight and has high power characteristics. As described above in detail, according to the
present invention, a lightweight and lightweight hv 妹 7'7-bolted Langevin vibrator for acoustic
wave transducer for medium is obtained-and industrial value is also obtained. It is great.
[0002]
Brief description of the drawings
[0003]
Fig. 1 is a schematic view of a bolt-clamped lung-pan transducer used for underwater ultrasonic
transducers, Fig. 2 is a model of the transducer front half section from the acoustic radiation end
to the vibration node, and Fig. 3 is an equivalent circuit Fig. 4 shows the relationship between the
normalized mass M of the front half of the vibrator and the shape of the vibrator, and Fig. 5
shows the stress 1 "2 m at the vibration node l of the piezoelectric ceramic part and the vibrator
shape 6 shows the relationship between stress Tbm acting on the vibration node of the bolt Tbo1
acting on the bolt at the junction with the front mass and the shape of the vibrator, and FIG. 7
shows the vibrator front half Figure shows the relationship between the figure of Merit FMm and
the oscillator shape for weight reduction including the electric system of the figure, Figure 8
shows the FMm and oscillator shape when using O-F RP as the front mass material Diagram
showing the relationship, Fig. 9 is a physical model diagram of the vibrator cow section from the
vibration node to the rear mass end of the bolt-clamped lung-pan vibrator, M2O Fig. 11 is a
vibrator using aluminum and stainless steel as the rear mass material. The second half of the
Figure of Merit FM ', shows the characteristic diagram.
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In the figure, 11 is a front mass, 1.2.12 'is a piezoelectric ceramic ring, 13 is a rear mass, 14.14'
is a bolt, 15 is a nut, 11 is a length of the front mass, L and L 'are piezoelectric ceramic parts
Length 14; length of rear mass 7o, Ao 'effective quarter wavelength 0) 1 wavelength S: cross
section of front mass S2: cross section of piezoelectric ceramic ring S3: cross section of bolt , S4
is the cross section of the rear mass, ks3 is the electromechanical coupling coefficient, Ra is the
acoustic radiation impedance, Zo +, Z6! e Z63 is characteristic acoustic impedance, β1, β2e, β3
are phase constants. Figure 1 Figure 2 Figure 3 Figure 4 o, z (1), 4 o, co, t: t t. Fig. 5 X IO "0 0.2
0.4 0.6 0.8 1.0 Fig. Z No. / J. Fig. 7 to -700, 10, 20, 3θ, 4D, 5 minutes / no. Floor 6 Fig. XlO -70
0.1 θ 2 θ 3 θ, 4 0.51 · / in Fig. 9 111 D Fig. 10 o o, t o, 2 '0.3 0.4 0.5.1.4/ n S 11 Fig. 0 0.1 o, 2
0.3 o, 7i θ, 51, /, G
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