JP3738646B2

JP3738646B2 - Phone-type sound insulator and transducer with phone-type sound insulator

Info

Publication number: JP3738646B2
Application number: JP2000077766A
Authority: JP
Inventors: 光彦南利; 義幸小澤
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 2000-03-15
Filing date: 2000-03-15
Publication date: 2006-01-25
Anticipated expiration: 2020-03-15
Also published as: JP2001268682A

Description

【０００１】
【発明の属する技術分野】
本発明は、任意方向の空中あるいは水中音波を広帯域で遮音する遮音体及び任意方向を遮音すると供にそれ以外の方向については無指向性化を実現する前記遮音体付き送受波器に関する。
【０００２】
【従来の技術】
音源と受音装置が共存する空間において、特定方向の音源が発する音波が受音装置の妨害音となる場合が多々ある。例えば、船舶に装備する魚群群探知器やソーナー等、音源より音を送波し目標物からの反射音を受音装置にて受波するシステムにおいて、船舶のプロペラノイズや船体からの放射雑音等が受音装置の妨害音となる場合である。
【０００３】
また、音源から音を常に放射し、そのエコー音を受音装置で受波する送受同時運用を考えた音響システムにおいて、音源からの直接音が、受音装置の妨害音になる場合等がある。
【０００４】
これらの問題を回避するために、従来は「吸音くさびの水圧特性」（海洋音響学会講演論文集、Ｐ１、１９９１年５月）に記載のゴム材に気泡を混入したクサビ状吸音ゴム等で音源の音を吸音したり、「水中伝搬音に対する障壁の遮音効果」（海洋音響学会講演論文集、Ｐ１３、１９９１年５月）記載の遮音体のように単なる金属壁で遮音していた。
【０００５】
しかしながら、前者のクサビ状吸音ゴムを使用した場合、水圧印加時に気泡がつぶれてしまうため、水深の深い場所では効果がなく、また長時間水中に放置すると水を吸収し特性が変化してしまい性能が劣化する等改良すべき点があった。
【０００６】
後者の金属壁を使用した場合は、音源と受音装置を結ぶ音響軸に対して垂直に反射面があるために、そこからの反射音が送受指向性に影響を及ぼす等の改良すべき点があった。
【０００７】
その他にホン型遮音体の例として「コニカル状バッフルを有する円筒送波器の指向性」（海洋音響学会講演論文集、Ｐ３９、１９９０年５月）に記載された、円筒送波器にコニカル形状のホン型遮音体を形成した例がある。この場合は、筐体反射音が送波器指向性に及ぼす影響の計算を示したに過ぎず、任意の方向の音波を広帯域で抑制する遮音効果は小さい。
【０００８】
また、任意方向の感度を抑制する手法として、次のような手法がある。一つは、アレイを構成しその指向性のヌルを感度抑制したい方向に向ける方法である。もう一つは音源音波と逆位相の音波を直接音と重畳させアクティブに音波を消す方法等である。
【０００９】
しかしながら、これらの方法では特定の周波数だけの遮音であり、広帯域に感度を抑制することは困難である。
【００１０】
【発明が解決しようとする課題】
本発明の目的は、上記点に鑑み、広帯域・高水圧下において任意の方向の遮音を可能とする遮音体を提供することにある。
【００１１】
また、この遮音体と球殻等の無指向性送受波器とを組み合わせ、任意の方向を遮音するとともにそれ以外の方向については、無指向性化を実現する送受波器を提供することにある。
【００１２】
【発明の実施形態】
以下、本発明の実施例について図面を用いて説明する。まず、遮音体に係わる実施形態を説明する。
【００１３】
図１、図２は、音源１、遮音体２、受音装置３との関係を示図、図３は、遮音体付き音源の指向性概念図であり、遮音方向の相対感度レベルと感度抑制指向幅を小さくするための技術を示している。
【００１４】
図４は、遮音方向が相対する第１と第２のホン型遮音体５、６の間に第３の遮音体７を挿入し、直径２ａの球殻音源４を有する遮音体モデルである。
【００１５】
図２６は、遮音体の原理図である。以下遮音の原理について説明する。図２６において、球殻音源４から遮音体方向に送波された直接波１３は、第１、第２、第３の遮音体５、６、７と媒体１７の境界及び遮音体内部を伝播、（１６）、第１の遮音体５と第３の遮音体７の接合部から回折波１４が発生する。この回折波１４は音波合成ポイント１８において合成し、図３に示すような遮音方向に指向性のローブ１９ができる。この回折波１４によって発生する指向性のローブ１９を小さくし、図３に示す感度抑制指向幅を狭くすることが本特許の目的である。
【００１６】
図２６において、目標の感度抑制指向幅を実現するために球殻音源４から遮音体方向に送波された直接波１３を第１の遮音体５により拡散させる。第１の遮音体５と第３の遮音体７の接合部から発生した回折波１４は、音波合成ポイント１８において合成するため、このポイントに第３の遮音体７を挿入すると回折波１４が第３の遮音体７により反射１５され、大きな遮音効果が得られるものである。
【００１７】
図４に示す遮音体５の寸法・形状パラメータを変化させ、遮音方向の相対感度レベルと感度抑制指向幅を評価する。評価（計算）は、医療用超音波装置及び水中音響機器等で実績のある時刻歴有限要素解析プログラムを利用することで可能である。（１）第１の遮音体５のホン形状係数μを変化させた場合
第１、第２の遮音体５、６を、図５に示すベッセルホンにて評価する。ここで形状係数をμ、ホン上下端部の断面積をそれぞれとS₀、S_Lと置くと、ベッセル・ホーンの断面半径xは数１の式で表すことができる。
【００１８】
【数１】

【００１９】
即ち、図５に示すように、小さい方の直径を２d、大きい方の直径を２Wと置き、形状係数μを変化させた時のホン形状関数の計算結果を図６に示す。ここでμ＝１．０はパラボラ、μ＝２．０はコニカル、μ＝∽はエクスポネンシャルホンとなる。ホンの先端に直径２ａなる球殻音源４を配置し、音を送波した時の遠距離音場における遮音方向の相対感度レベルと感度抑制指向幅を算出した。ここで、第２の遮音体６の形状係数は２に固定した。そのときの計算結果を図７、図８に示す。ｋａは球殻音源４の半径ａを基準とした周波数の関数であり、波数ｋはｋ＝２π／λ（λ計算周波数における媒体１７の波長）で表すことができる。図からわかるように、２つの評価項目が安定した値となるのはμ＞２である。この範囲を越えμ≦２とすると、相対感度レベルは小さくなるが、感度抑制指向幅が広くなってしまい性能が劣化する。つまり、ホンの形状がコニカルホンよりも小さくした方が安定した特性になることを示している。
【００２０】
（２）第２の遮音体６のホン形状係数ψを変化させた場合
第２の遮音体６のホン形状は、上記数１の形状係数μをψに置き換えて計算した。また第１の遮音体５の形状係数μを２に固定した。そのときの計算結果を図９、図１０に示す。ψを小さくすると相対感度レベルは小さくなり第１の遮音体５と同傾向の結果となるが、感度抑制指向幅については形状係数ψを変化させてもほぼ一定値となる。
【００２１】
上記（１）、（２）の結果より、第１、第２の遮音体５、６のホン形状係数μ、ψは、遮音方向の相対感度レベルに影響を与えるが、感度抑制指向幅については、第１の遮音体５の形状係数μのみ関係あり、第２の遮音体６の形状係数ψには影響を受けないことがわかる。
【００２２】
（３）第３の遮断体７の長さｌを変化させた場合
第１の遮音体５と第２の遮音体７の形状係数をそれぞれμ＝３．０、ψ＝２．０に固定し、第３の遮音体７の長さｌを変化させた場合の計算結果を図１１、図１２に示す。相対感度レベルは、ｌが大きくなればなるほど小さくなるが、感度抑制指向幅は変化しない。つまり第３の遮音体７は、第１の遮音体５と第３の遮音体７の接合部で拡散された回折波１４が合成するポイント１８にあるため、第３の遮音体７にて回折波１４を散乱・反射１５させることで、後方に発生する指向性のローブ１９を抑制することができる。従って、長ければ長いほど回折波１４の合成を阻止できるため、ｌの長さに比例して遮音方向の相対感度レベルが小さくなる。
【００２３】
（４）遮音体の板厚ｔを変化させた場合
上記（１）〜（３）は形状効果確認のため、遮音材料を真空状態で計算した。実際、空中、水中等の空間において真空状態を保つためには、何らかのきょう体が必要になる。そこで遮音体材料をＡＬとし、この板厚を変化させ第１の遮音体５と第２の遮音体７の形状係数をそれぞれμ＝３．０、ψ＝２．０に固定し指向性を計算した。その結果を図１３、図１４、図１５に示す。これらの結果からわかるように、中実状態では遮音体内部に透過した音波が遮音方向に再放射し、指向性の乱れが遮音方向に発生している。このため遮音方向の指向性のローブも大きくなってしまう。この透過波の影響を押さえるため板厚ｔを小さくすると、その結果、小さくすればするほど真空状態の指向性に近づく。具体的には遮音周波数における媒体の波長をλとすると板厚ｔが波長の１／１０λ以下で、遮音方向の指向性乱れがなくなり、ローブも小さくなることがわかる。また、金属で遮音体を構成できるため水圧特性が良い。
【００２４】
（５）遮音形状を相似比で大きくした場合
第１及び第２の遮音体５、６の形状係数はそれぞれμ＝３．０、ψ＝２．０に固定で、遮音体を相似的に大きくし計算した。また遮音体の材料は真空状態で計算した。計算結果を図１６、図１７、図１８に示す。相対感度レベルは遮音体が大きければ大きいほど小さくなるが、感度抑制指向幅は変化しない。つまり、遮音体端面の大きい方の直径２Ｗは感度抑制指向幅の開口角とほぼ同等の大きさとなり、遮音体の高さＬは遮音周波数における媒体の波長の３倍以上で効果が現れる。
【００２５】
上記（１）〜（５）の結果より、第１の遮音体の形状係数がμ＞２、第１、第２の遮音体５、６の長さＬ及び遮音体の厚みｔが、それぞれ遮音周波数における媒体の音波波長の４倍以上及び１／１０以下のとき有効な遮音効果が得られる。第３の遮音体７の長さｌについては長さに比例して遮音効果が得られる。
【００２６】
図１９は、本発明の遮音体を示す図である。同図において、船底へ装備したソーナーアレイ９から全方位へ音波を発生する。船尾方向の音波は第１の遮音体５から船首方向へ反射することなく、第１の遮音体５の開口角にほぼ等しい指向幅で船尾方向へ音を放射する。その一部の音波が回折波として船尾方向へ回り込むが、第３の遮音体７により船尾方向への音を反射・減衰させる。一方受波は船尾方向のプロペラ１０が雑音源となるが、送受指向性は同じであるため、プロペラ雑音は第３の遮音体７と第１の遮音体５により減衰し、ソーナーアレイ９へ到達することはない。従って、エコー音をＳ／Ｎの良い状態で受信することができる。
【００２７】
図２０〜図２５に本発明に関わる遮音体付き球殻送受波器の実施例を示す。
【００２８】
図２０は、球殻圧電素子１１に水密用ウレタン樹脂１２でモールドした音源１に本発明の第１の遮音体５を装着した送受波器の実施例である。同図において、ケーブル８を介して球殻圧電素子１１に電気信号を供給すると、電気エネルギーを振動エネルギーへ変換し音波を放射する。音源形状が球殻であるため、広帯域で全方位に音波を放射すため、第１の遮音体５にも音波が到来する。第１の遮音体５へ到来した音波は遮音体の外形にそって音波が拡散するため、遮第１の遮音体５の開口角にほぼ等しい指向性で音波を放射する。従って、受音装置３方向の音のレベルが抑制され、受音装置３に入射する直接音とエコー音を分離することができ、送受波同時運用が可能となる。音源１と受音装置３が反対に構成されても良い。
図２１は、球殻音源１と受音装置３を本発明の第１の遮音体５と第２の遮音体６で結合した例である。原理は図２０と同じであるが、送受供に遮音体を備えているため、遮音効果は図２０に比較すると大きくなる。
図２２は、図２１の送受波器に第３の遮音体７を装備した例である。音源から放射した音波は第１の遮音体５で拡散され、第３の遮音体７へ回折波がぶつかる。この回折波は第３の遮音体７で反射・透過・減衰され受波装置３方向での音波を減衰させエコー音をＳ／Ｎの良い状態で受波することができる。
【００２９】
図２３は、図２２の変形例である。回折波は第１の遮音体５から離れた位置にて合成するため、この位置に第３の遮音体７を配置しても良い。
【００３０】
図２４は、図２２の変形例である。第１の遮音体５、第２の遮音体６、第３の遮音体７で構する遮音体を複数個、音源１と受音装置３の間に構成した実施例である。
【００３１】
図２５は、図２２の変形例である。回折波を第１の遮音体５と第３の遮音体７の間、及び第２の遮音体６と第３の遮音体７の間の空間で繰り返し反射させ減衰させる例である。
【００３２】
【発明の効果】
以上説明したように、本発明は広帯域・高水圧下において、任意方向の遮音を効果的に実現し、またこの遮音体と球殻等の無指向性送受波器とを組み合わることで、任意の方向を遮音するとともにそれ以外の方向について無指向性化を実現する。
【図面の簡単な説明】
【図１】本発明の音源―遮音体―受音装置の位置関係を示す概念図。
【図２】本発明の音源―遮音体―受音装置の位置関係を示す概念図。
【図３】本発明の遮音体付き音源の指向性概念図。
【図４】本発明の計算パラメータを示す図。
【図５】本発明の計算パラメータを示す図。
【図６】本発明の計算結果を示す特性図。
【図７】本発明の計算結果による感度レベルを示す特性図。
【図８】本発明の計算結果による感度抑制指向幅を示す特性図。
【図９】本発明の計算結果による遮音方向相対感度レベルを示す特性図。
【図１０】本発明の計算結果による感度抑制指向幅を示す特性図。
【図１１】本発明の計算結果による遮音方向相対感度レベルを示す特性図。
【図１２】本発明の計算結果による感度抑制指向幅を示す特性図。
【図１３】本発明の計算結果による指向性を示す図。
【図１４】本発明の計算結果による遮音方向相対感度レベルを示す特性図。
【図１５】本発明の計算結果による感度抑制指向幅を示す特性図。
【図１６】本発明の計算結果による指向性を示す図。
【図１７】本発明の計算結果による遮音方向相対感度レベルを示す特性図。
【図１８】本発明の計算結果による感度抑制指向幅を示す特性図。
【図１９】本発明の遮音体の一実施例を示す図。
【図２０】本発明の遮音体付き送受波器の一実施例を示す図。
【図２１】本発明の遮音体付き送受波器の他の実施例を示す図。
【図２２】本発明の遮音体付き送受波器の更に他の実施例を示す図。
【図２３】本発明の遮音体付き送受波器の実施例を示す図。
【図２４】本発明の遮音体付き送受波器の実施例を示す図。
【図２５】本発明の遮音体付き送受波器の実施例を示す図。
【図２６】本発明の遮音体の原理図。
【符号の説明】
１・・・・・音源
２・・・・・遮音体
３・・・・・受音装置
４・・・・・球殻音源
５・・・・・第１の遮音体
６・・・・・第２の遮音体
７・・・・・第３の遮音体
８・・・・・ケーブル
９・・・・・ソーナーアレイ
１０・・・・プロペラ
１１・・・・球殻圧電素子
１２・・・・水密用ウレタン樹脂
１３・・・・直接波
１４・・・・回折波
１５・・・・反射波
１６・・・・伝搬波
１７・・・・媒体
１８・・・・回折波の合成ポイント
１９・・・・指向性のローブ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sound insulating body for insulating a wide range of aerial or underwater sound waves in an arbitrary direction, and the above-mentioned sound receiving body with a sound insulating body that realizes omnidirectionality in other directions when sound is blocked in an arbitrary direction.
[0002]
[Prior art]
In a space where a sound source and a sound receiving device coexist, a sound wave emitted by a sound source in a specific direction often becomes an interference sound of the sound receiving device. For example, in a system that transmits sound from a sound source and receives a reflected sound from a target with a sound receiving device such as a fish school detector or sonar equipped on the ship, the propeller noise of the ship, radiation noise from the hull, etc. Is a disturbance sound of the sound receiving device.
[0003]
Also, in an acoustic system that considers simultaneous transmission and reception where sound is always emitted from the sound source and the echo sound is received by the sound receiving device, the direct sound from the sound source may become an interference sound of the sound receiving device. .
[0004]
In order to avoid these problems, a sound source is conventionally produced with a wedge-shaped sound absorbing rubber or the like in which bubbles are mixed in a rubber material described in “Hydraulic characteristics of sound absorbing wedge” (Journal of Oceanographic Society of Japan, P1, May 1991). The sound was absorbed by a mere metal wall like the sound insulator described in “The sound insulation effect of the barrier against the underwater propagation sound” (Journal of Ocean Acoustics Society, P13, May 1991).
[0005]
However, if the former wedge-shaped sound absorbing rubber is used, bubbles will be crushed when water pressure is applied, so there is no effect in deep water, and if left in water for a long time, the water will be absorbed and its characteristics will change. There was a point that should be improved, such as deterioration.
[0006]
When the latter metal wall is used, there is a reflecting surface perpendicular to the acoustic axis connecting the sound source and the sound receiving device, so the reflected sound from there affects the directivity of transmission and reception. was there.
[0007]
In addition, as an example of a phone-type sound insulator, the conical shape is described in the cylindrical transmitter described in “Directivity of a cylindrical transmitter having a conical baffle” (Journal of Ocean Acoustics Society, P39, May 1990). There is an example of forming a phone-type sound insulator. In this case, only the calculation of the influence of the case reflected sound on the transmitter directivity is shown, and the sound insulation effect for suppressing the sound wave in an arbitrary direction in a wide band is small.
[0008]
In addition, as a technique for suppressing the sensitivity in an arbitrary direction, there are the following techniques. One is a method of configuring an array and directing the directivity null in a direction in which sensitivity is to be suppressed. The other is a method of superimposing a sound wave having a phase opposite to that of the sound source sound wave directly on the sound and actively extinguishing the sound wave.
[0009]
However, these methods provide sound insulation only at a specific frequency, and it is difficult to suppress sensitivity over a wide band.
[0010]
[Problems to be solved by the invention]
In view of the above points, an object of the present invention is to provide a sound insulator capable of sound insulation in an arbitrary direction under a wide band and high water pressure.
[0011]
Another object of the present invention is to provide a transducer that combines this sound insulator and a non-directional transducer such as a spherical shell to provide sound insulation in any direction and realize omnidirectionality in other directions. .
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. First, an embodiment related to a sound insulator will be described.
[0013]
FIGS. 1 and 2 are diagrams showing the relationship between the sound source 1, the sound insulator 2, and the sound receiving device 3. FIG. 3 is a conceptual diagram of directivity of the sound source with the sound insulator, and the relative sensitivity level and sensitivity suppression in the sound insulation direction. A technique for reducing the directivity width is shown.
[0014]
FIG. 4 shows a sound insulator model having a spherical sound source 4 having a diameter of 2a, in which a third sound insulator 7 is inserted between the first and second phone-

type sound insulators

5 and 6 whose sound insulation directions are opposite to each other.
[0015]
FIG. 26 is a principle diagram of a sound insulator. The principle of sound insulation will be described below. In FIG. 26, the direct wave 13 transmitted from the spherical shell sound source 4 toward the sound insulation body propagates through the boundary between the first, second and third

sound insulation bodies

5, 6, 7 and the medium 17 and the inside of the sound insulation body. (16) A diffracted wave 14 is generated from the joint between the first sound insulator 5 and the third sound insulator 7. This diffracted wave 14 is synthesized at a sound wave synthesis point 18 to form a directional lobe 19 in the sound insulation direction as shown in FIG. The purpose of this patent is to reduce the directivity lobe 19 generated by the diffracted wave 14 and to narrow the sensitivity suppression directivity width shown in FIG.
[0016]
In FIG. 26, the direct sound wave 13 transmitted from the spherical shell sound source 4 toward the sound insulation body is diffused by the first sound insulation body 5 in order to realize the target sensitivity suppression directivity width. Since the diffracted wave 14 generated from the joint between the first sound insulator 5 and the third sound insulator 7 is synthesized at the sound wave synthesis point 18, when the third sound insulator 7 is inserted at this point, the diffracted wave 14 becomes the first wave. 3 is reflected 15 by the sound insulation body 7, and a large sound insulation effect is obtained.
[0017]
The size and shape parameters of the sound insulator 5 shown in FIG. 4 are changed, and the relative sensitivity level and the sensitivity suppression directing width in the sound insulation direction are evaluated. Evaluation (calculation) can be performed by using a time history finite element analysis program that has a proven record in medical ultrasonic devices, underwater acoustic devices, and the like. (1) When the phone shape factor μ of the first sound insulator 5 is changed: The first and

second sound insulators

5 and 6 are evaluated by the Bessel phone shown in FIG. Here, when the shape factor is μ and the cross-sectional areas of the upper and lower end portions of the phon are S ₀ and S _L , respectively, the cross-sectional radius x of the Bessel horn can be expressed by the equation (1).
[0018]
[Expression 1]

[0019]
That is, as shown in FIG. 5, the calculation result of the phone shape function when the smaller diameter is 2d and the larger diameter is 2W and the shape factor μ is changed is shown in FIG. Here, μ = 1.0 is a parabola, μ = 2.0 is a conical, and μ = ∽ is an exponential phone. A spherical shell sound source 4 having a diameter of 2a was arranged at the tip of the phone, and the relative sensitivity level and sensitivity suppression directivity width in the sound insulation direction in the far field when the sound was transmitted were calculated. Here, the shape factor of the second sound insulator 6 was fixed to 2. The calculation results at that time are shown in FIGS. ka is a frequency function based on the radius a of the spherical shell sound source 4, and the wave number k can be expressed by k = 2π / λ (the wavelength of the medium 17 at the λ calculation frequency). As can be seen from the figure, it is μ> 2 that the two evaluation items have stable values. If this range is exceeded and μ ≦ 2, the relative sensitivity level becomes small, but the sensitivity suppression directing width becomes wide and the performance deteriorates. That is, it is shown that the characteristic becomes more stable when the shape of the phone is smaller than that of the conical phone.
[0020]
(2) When the phone shape factor ψ of the second sound insulator 6 is changed The phone shape of the second sound insulator 6 was calculated by replacing the shape factor μ of Equation 1 with ψ. The shape factor μ of the first sound insulator 5 was fixed to 2. The calculation results at that time are shown in FIGS. When ψ is made small, the relative sensitivity level becomes small and results in the same tendency as the first sound insulator 5, but the sensitivity suppression directing width becomes a substantially constant value even if the shape factor ψ is changed.
[0021]
From the results of (1) and (2) above, the phone shape factors μ and ψ of the first and second

sound insulation bodies

5 and 6 affect the relative sensitivity level in the sound insulation direction. It can be seen that only the shape factor μ of the first sound insulator 5 is related, and the shape factor ψ of the second sound insulator 6 is not affected.
[0022]
(3) When the length l of the third insulator 7 is changed, the shape factors of the first and

second insulators

5 and 7 are fixed to μ = 3.0 and ψ = 2.0, respectively. 11 and 12 show the calculation results when the length l of the third sound insulator 7 is changed. The relative sensitivity level decreases as l increases, but the sensitivity suppression directivity width does not change. In other words, the third sound insulator 7 is located at the point 18 where the diffracted waves 14 diffused at the joint between the first sound insulator 5 and the third sound insulator 7 are combined, so that the third sound insulator 7 is diffracted by the third sound insulator 7. By scattering / reflecting the wave 14, the directional lobe 19 generated behind can be suppressed. Therefore, the longer the length, the more the synthesis of the diffracted wave 14 can be prevented, and the relative sensitivity level in the sound insulation direction becomes smaller in proportion to the length of l.
[0023]
(4) When the thickness t of the sound insulating body is changed In the above (1) to (3), the sound insulating material was calculated in a vacuum state in order to confirm the shape effect. In fact, in order to maintain a vacuum state in a space such as air or water, some kind of housing is required. Therefore, the sound insulation material is set to AL, and the plate thickness is changed, and the shape factors of the first sound insulation body 5 and the second sound insulation body 7 are fixed to μ = 3.0 and ψ = 2.0, respectively, and the directivity is calculated. did. The results are shown in FIG. 13, FIG. 14, and FIG. As can be seen from these results, in the solid state, the sound wave transmitted through the inside of the sound insulation body re-radiates in the sound insulation direction, and the directional disturbance occurs in the sound insulation direction. For this reason, the directivity lobe in the sound insulation direction also becomes large. If the plate thickness t is reduced in order to suppress the influence of the transmitted wave, as a result, the directivity in the vacuum state becomes closer as the thickness is reduced. Specifically, when the wavelength of the medium at the sound insulation frequency is λ, the plate thickness t is 1 / 10λ or less of the wavelength, and the directivity disturbance in the sound insulation direction is eliminated and the lobe is also reduced. Moreover, since the sound insulator can be made of metal, the water pressure characteristic is good.
[0024]
(5) When the sound insulation shape is increased by the similarity ratio, the shape factors of the first and second

sound insulation bodies

5 and 6 are fixed at μ = 3.0 and ψ = 2.0, respectively, and the sound insulation body is increased in a similar manner. And calculated. The sound insulation material was calculated in a vacuum state. The calculation results are shown in FIG. 16, FIG. 17, and FIG. The relative sensitivity level decreases as the sound insulator is larger, but the sensitivity suppression directivity width does not change. That is, the larger diameter 2W of the end face of the sound insulation body is almost the same size as the opening angle of the sensitivity suppression directivity width, and the height L of the sound insulation body is effective when it is at least three times the wavelength of the medium at the sound insulation frequency.
[0025]
From the results of the above (1) to (5), the shape factor of the first sound insulator is μ> 2, the length L of the first and

second sound insulators

5 and 6, and the thickness t of the sound insulator are respectively sound insulation. An effective sound insulation effect is obtained when the sound wave wavelength of the medium is 4 times or more and 1/10 or less at the frequency. As for the length l of the third sound insulator 7, a sound insulation effect is obtained in proportion to the length.
[0026]
FIG. 19 is a diagram showing a sound insulator of the present invention. In the figure, sound waves are generated in all directions from a sonar array 9 installed on the ship bottom. The sound waves in the stern direction radiate sound in the stern direction with a directivity width substantially equal to the opening angle of the first sound insulator 5 without being reflected from the first sound insulator 5 in the bow direction. Some of the sound waves circulate in the stern direction as diffracted waves, but the sound in the stern direction is reflected and attenuated by the third sound insulator 7. On the other hand, the propeller 10 in the stern direction serves as a noise source for the received wave, but since the transmission and reception directivities are the same, the propeller noise is attenuated by the third sound insulator 7 and the first sound insulator 5 and reaches the sonar array 9. Never do. Therefore, the echo sound can be received with a good S / N.
[0027]
20 to 25 show an embodiment of a spherical shell transducer with a sound insulator according to the present invention.
[0028]
FIG. 20 shows an embodiment of a transducer in which the first sound insulator 5 of the present invention is mounted on the sound source 1 molded with the watertight urethane resin 12 on the spherical shell piezoelectric element 11. In the figure, when an electric signal is supplied to the spherical shell piezoelectric element 11 via the cable 8, the electric energy is converted into vibration energy and a sound wave is emitted. Since the sound source shape is a spherical shell, sound waves are radiated in all directions in a wide band, so that sound waves also arrive at the first sound insulator 5. Since the sound wave arriving at the first sound insulator 5 diffuses along the outer shape of the sound insulator, the sound wave is emitted with directivity substantially equal to the opening angle of the first sound insulator 5. Accordingly, the sound level in the direction of the sound receiving device 3 is suppressed, the direct sound incident on the sound receiving device 3 and the echo sound can be separated, and simultaneous transmission and reception operations are possible. The sound source 1 and the sound receiving device 3 may be configured oppositely.
FIG. 21 is an example in which the spherical shell sound source 1 and the sound receiving device 3 are coupled by the first sound insulator 5 and the second sound insulator 6 of the present invention. The principle is the same as in FIG. 20, but the sound insulation effect is greater than that in FIG.
FIG. 22 shows an example in which the third sound insulator 7 is installed in the transducer shown in FIG. The sound wave radiated from the sound source is diffused by the first sound insulator 5 and a diffracted wave collides with the third sound insulator 7. This diffracted wave is reflected, transmitted and attenuated by the third sound insulator 7 to attenuate the sound wave in the direction of the wave receiving device 3 and receive the echo sound in a good S / N state.
[0029]
FIG. 23 is a modification of FIG. Since the diffracted wave is synthesized at a position away from the first sound insulator 5, the third sound insulator 7 may be disposed at this position.
[0030]
FIG. 24 is a modification of FIG. This is an embodiment in which a plurality of sound insulation bodies composed of the first sound insulation body 5, the second sound insulation body 6, and the third sound insulation body 7 are configured between the sound source 1 and the sound receiving device 3.
[0031]
FIG. 25 is a modification of FIG. In this example, the diffracted wave is repeatedly reflected and attenuated in the space between the first sound insulator 5 and the third sound insulator 7 and between the second sound insulator 6 and the third sound insulator 7.
[0032]
【The invention's effect】
As described above, the present invention effectively realizes sound insulation in an arbitrary direction under a wide band and high water pressure, and can be arbitrarily combined by combining this sound insulation body with an omnidirectional transducer such as a spherical shell. In addition to sound insulation, the other directions are made omnidirectional.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing a positional relationship of a sound source—a sound insulator—a sound receiving device according to the present invention.
FIG. 2 is a conceptual diagram showing a positional relationship of a sound source—a sound insulator—a sound receiving device according to the present invention.
FIG. 3 is a conceptual diagram of directivity of a sound source with a sound insulator according to the present invention.
FIG. 4 is a diagram showing calculation parameters of the present invention.
FIG. 5 is a diagram showing calculation parameters of the present invention.
FIG. 6 is a characteristic diagram showing the calculation result of the present invention.
FIG. 7 is a characteristic diagram showing a sensitivity level according to a calculation result of the present invention.
FIG. 8 is a characteristic diagram showing the sensitivity suppression directivity width according to the calculation result of the present invention.
FIG. 9 is a characteristic diagram showing a sound insulation direction relative sensitivity level according to a calculation result of the present invention.
FIG. 10 is a characteristic diagram showing a sensitivity suppression directivity width according to a calculation result of the present invention.
FIG. 11 is a characteristic diagram showing a sound insulation direction relative sensitivity level according to a calculation result of the present invention.
FIG. 12 is a characteristic diagram showing the sensitivity suppression directivity width according to the calculation result of the present invention.
FIG. 13 is a diagram showing directivity according to a calculation result of the present invention.
FIG. 14 is a characteristic diagram showing a sound insulation direction relative sensitivity level according to a calculation result of the present invention.
FIG. 15 is a characteristic diagram showing a sensitivity suppression directivity width according to a calculation result of the present invention.
FIG. 16 is a diagram showing directivity according to the calculation result of the present invention.
FIG. 17 is a characteristic diagram showing a sound insulation direction relative sensitivity level according to a calculation result of the present invention.
FIG. 18 is a characteristic diagram showing the sensitivity suppression directivity width according to the calculation result of the present invention.
FIG. 19 is a view showing an embodiment of a sound insulator according to the present invention.
FIG. 20 is a diagram showing an embodiment of a transducer with a sound insulator according to the present invention.
FIG. 21 is a diagram showing another embodiment of a transducer with a sound insulator according to the present invention.
FIG. 22 is a view showing still another embodiment of a transducer with a sound insulator according to the present invention.
FIG. 23 is a diagram showing an embodiment of a transducer with a sound insulator according to the present invention.
FIG. 24 is a diagram showing an embodiment of a transducer with a sound insulator according to the present invention.
FIG. 25 is a diagram showing an embodiment of a transducer with a sound insulator according to the present invention.
FIG. 26 is a principle diagram of a sound insulator according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Sound source 2 ... Sound insulation body 3 ... Sound receiving device 4 ... Spherical shell sound source 5 ... 1st sound insulation body 6 ... 2nd sound insulator 7 ... 3rd sound insulator 8 ... cable 9 ... sonar array 10 ... propeller 11 ... spherical shell piezoelectric element 12 ...・ Watertight urethane resin 13... Direct wave 14... Diffraction wave 15... Reflected wave 16. .... Directive lobes

Claims

A phone-type sound insulator composed of a metal, plastic, or a material corresponding to an air layer that blocks sound waves in the air or water,
A phone-type sound insulator having the following formula 1 and a shape constant μ of the phone set to μ> 2.

A phone type characterized in that the sound insulation body according to claim 1 is provided with a second sound insulation body in which the shape factor μ of the phone is μ ≧ 0 and the sound insulation direction is opposite to the first sound insulation body. Sound insulation.

The sound insulation body according to claim 1, wherein a third sound insulation body for reflecting / attenuating a diffracted wave is provided between the sound insulation direction of sound waves or between the first and second sound insulation bodies. A phone-type sound insulator.

4. The sound insulation body according to claim 1, wherein the first and second sound insulation bodies have a height L that is three times or more the wavelength of the medium at the sound insulation frequency.

5. The sound insulation body according to claim 1, wherein the sound insulation body is made of metal and has a thickness t of 1/10 or less of a wavelength of a medium at a sound insulation frequency.

6. A transmitter / receiver with a phone-type sound insulator, wherein the sound insulator according to claim 1 is provided with an omnidirectional transmitter / receiver.