CN106558301B - low frequency directional underwater acoustic transducer - Google Patents

Abstract

The invention provides a low-frequency directional underwater acoustic transducer, comprising a radiation shell, four active drive units and an intermediate mass block. The radiation shell is formed by alternately connecting four sections of curved beams and four sections of straight beams. The cross-sectional shape of the intermediate mass block is square and is located in the center of the radiation shell, four active drivers are respectively arranged between the four straight beams and the intermediate mass block, and the distance between the intermediate mass block and the corresponding straight beam is less than The length of the source drive. The invention utilizes the asymmetry of the shell structure to form cardioid directivity or super directivity, and utilizes the low-frequency effect and amplification effect of the shell bending vibration to form low-frequency high-power radiation. It can be used in the fields of low frequency active sonar, long-distance communication, geoacoustic propagation research and marine geological research.

Description

low frequency directional underwater acoustic transducer

technical field

The invention relates to a transducer, in particular to a low-frequency directional underwater acoustic transducer.

Background technique

At present, the monitoring of marine environment mainly relies on sound waves. Low-frequency sound waves have small absorption loss and long propagation distance in seawater, and have been widely used in marine environment monitoring. Therefore, the low-frequency underwater acoustic transducer, as the core component of the low-frequency underwater acoustic system, has become the focus of marine acoustics researchers at home and abroad. In addition, the directional transducer can significantly improve the working distance, improve the signal-to-noise ratio, reduce interference, and at the same time, because it can transmit information in a directional manner, thereby improving the reliability and confidentiality of communication. Therefore, the research of low-frequency directional transducer has important research significance for underwater communication and submarine warfare.

When the size of a transmitter or receiver can be compared with the wavelength of the sound wave in the medium in which it is located, the sound pressure in the sound field has a certain distribution with different azimuths, thus forming directivity. Therefore, in the high-frequency background, directional transducers are usually easier to implement. However, in the low frequency background, it is often difficult to form directivity due to the small size of the transducer compared to the wavelength.

Butler et al. developed a directional IV flextensional transducer. The flextensional transducer is driven by two sets of piezoelectric stacks respectively. When the excitation of the two sets is adjusted to achieve an appropriate phase, the radiating surface of the transducer does not move and radiates at the same time, showing a cardioid directivity.

Another way to achieve low frequency directivity is to use a baffle. K.P.B.Moosad uses anti-sound material as baffle to realize directional IV flextensional transducer.

Low frequency transducer directivity is usually achieved by special excitation. The quadrilateral flextensional transducer can realize directional acoustic emission only through the convex and concave change of the shell structure without special excitation mode. At the same time, due to the lever effect of the curved shell, high-power emission can be achieved, so the quadrilateral flextensional transducer can achieve low-frequency high-power directional emission.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a low frequency directivity underwater acoustic transducer in order to realize low frequency cardioid directivity or super directivity.

The purpose of the present invention is achieved as follows: including a radiation shell, four active drive units and an intermediate mass block, the radiation shell is formed by alternately connecting four sections of curved beams and four sections of straight beams, and the intermediate mass block is formed by alternately connecting four sections of curved beams and four sections of straight beams. The cross-sectional shape is square and is located in the center of the radiation shell. Four active drivers are respectively arranged between the four straight beams and the intermediate mass, and the distance between the intermediate mass and the corresponding straight beam is smaller than the length of the active driver.

The present invention also includes such structural features:

1. The radiation shell is a three-concave and one-convex radiation shell or a three-convex and one concave shell.

2. The active driver is a piezoelectric crystal stack. The piezoelectric crystal stack is made of N pieces of rectangular piezoelectric ceramics bonded together, and N is not less than an even number of 2. The rectangular piezoelectric ceramics are polarized along the thickness direction. An electrode sheet is arranged between the piezoelectric ceramic sheets.

3. The active driver comprises two transition blocks, a round rod made of rare earth giant magnetostrictive material arranged between the two transition blocks, and a permanent magnet sheet is provided at the contact point between the round rod and the corresponding transition block. , the two transition blocks are also provided with coil bobbins, and coils are wound on the bobbins.

Compared with the prior art, the beneficial effect of the present invention is: the present invention utilizes the asymmetry of the casing instead of the change of the excitation mode to form the directivity, which is a new method for forming the low frequency directivity, that is, the present invention The asymmetry of the casing structure is used to form cardioid directivity or super directivity, and the low-frequency and high-power radiation is formed by using the low-frequency effect and amplification effect of the casing bending vibration. The invention can be applied to the fields of low-frequency active sonar, long-distance communication, geoacoustic propagation research, marine geological research and the like.

Description of drawings

1 is a top view of a schematic structural diagram of a quadrilateral flextensional transducer in the form of a three-concave and one-convex curved beam in the radiation shell of the present invention;

2 is an isometric side view of a schematic structural diagram of a quadrilateral flextensional transducer in the form of three concave and one convex curved beams in the radiation shell of the present invention;

3 is a top view of a schematic structural diagram of a quadrilateral flextensional transducer in the form of a three-convex and one concave curved beam in the radiation shell of the present invention;

4 is an isometric side view of a schematic structural diagram of a quadrilateral flextensional transducer in the form of a three-convex and one concave curved beam in the radiation shell of the present invention;

5 is a schematic diagram of the electrode wiring of the present invention using piezoelectric ceramics as a driving element;

6 is a schematic cross-sectional view of the driving element using rare earth giant magnetostrictive rods as the driving element in the present invention;

7 is a schematic diagram showing the principle of the radiation shell of the present invention using a three-concave-one-convex curved shell or a three-convex one-concave curved shell to achieve directional emission;

The meanings of the symbols in the drawings are: 1- three concave and one convex radiation shell, 2- piezoelectric drive unit, 3- center mass block, 4- three convex and one concave radiation shell, 5- coil bobbin, 6- -Transition block, 7-Permanent magnet piece, 8-Rare earth giant magnetostrictive rod 9-Coil.

Detailed ways

The present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

Embodiment 1: Referring to FIG. 1 and FIG. 2 , the radiation housing in this embodiment is formed by alternately connecting three concave and one convex curved beams and four straight beams, and is made of aluminum alloy material.

The driving unit in this embodiment is a piezoelectric crystal stack. As shown in FIG. 5 , the piezoelectric crystal stack 2 is formed by bonding N pieces of rectangular piezoelectric ceramic sheets, where N is an even number ≥ 2, and the thickness of the rectangular piezoelectric ceramic is Directional polarization, an electrode piece is placed between every two piezoelectric ceramic pieces to weld the lead wire, and the electrode piece is made of red copper material. The piezoelectric ceramic sheets are connected in parallel. The piezoelectric ceramic sheet and the metal sheet are bonded one by one with epoxy resin to form a driving element, and there are four driving elements in this embodiment. The length of the piezoelectric crystal stack 2 is greater than the distance between the middle mass block 3 and the inner wall of the corresponding straight beam. The radiation shell 1 is deformed in advance, and the driving force is driven by the pressure generated by increasing the distance between the inner wall of the corresponding straight beam and the middle mass block 3. The unit 2 is fixed between the straight beam and the intermediate mass block 3 , and the piezoelectric crystal stack 2 is rigidly connected with the inner wall of the straight beam and the intermediate mass block 3 .

When the transducer is working, an alternating current load is applied to the piezoelectric ceramic driving element 2. Due to the piezoelectric effect of the piezoelectric ceramic, the piezoelectric ceramic stack 2 produces longitudinal stretching vibration, and the radiation shell is excited through the mechanical coupling with the radiation shell 1. Bending vibration of body 1. The directional emission of the transducer is achieved by the structural asymmetry of the radiation housing 1 .

The driving unit in this embodiment can also be replaced by a round rod made of rare earth giant magnetostrictive material. As shown in FIG. 6 , a group of excitation coils 9 are wound around the round bar, and the excitation coils 9 are enclosed in a closed magnetic circuit made of a material with high magnetic permeability. The sum of the lengths of the rare earth giant magnetostrictive round rod 8 and the two transition blocks is greater than the distance between the central mass block 3 and the inner wall of the corresponding straight beam. Using the pressure generated by increasing the distance between the inner wall of the corresponding straight beam and the middle mass block 3 , the round bar is fixed between the inner wall of the straight beam and the central mass block 3 , and the round bar 8 is rigidly connected to the inner wall of the straight beam and the central mass block 3 .

The intermediate mass in this embodiment is a rectangular parallelepiped processed from aluminum alloy.

The radiation housing 1 and the intermediate mass block 3 in this embodiment can be made of stainless steel, steel, titanium alloy, glass fiber or carbon fiber in addition to aluminum alloy.

The low-frequency directional flextensional transducer in this embodiment may also adopt an overflow structure in addition to being sealed by a cover plate.

Embodiment 2: As shown in FIGS. 3 and 4 , in this embodiment, the radiation housing 4 is formed by alternately connecting three convex and one concave curved beams and four straight beams. Made of aluminum alloy material.

The rest of this embodiment is the same as Embodiment 1.

To sum up, the present invention essentially includes a radiation casing, an active driver, and an intermediate mass. The radiation shell is formed by alternately connecting three concave and one convex or three convex and one concave curved beams and four straight beams. There are four active drivers, which are respectively fixed by intermediate mass blocks and corresponding straight beams. The intermediate mass block is a rectangular parallelepiped, located in the center of the radiation shell, and the distance between one side surface of the intermediate mass block and the inner wall of the corresponding straight beam is smaller than the length of a single active driver. The invention utilizes the asymmetry of the casing structure to form cardioid directivity or super directivity, and utilizes the low frequency effect and amplification effect of the casing bending vibration to form low frequency high power radiation. The driver is placed inside the radiation shell, between the straight beam and the intermediate mass block, and is rigidly connected with the two: the radiation shell is deformed in advance, and the pressure generated by increasing the distance between the inner wall of the corresponding straight beam and the intermediate mass block is used. Fix the driver between the inner wall of the straight beam and the middle mass.

Further, the active driver is a piezoelectric crystal stack, and the piezoelectric crystal stack is formed by bonding N pieces of rectangular piezoelectric ceramic sheets, where N is an even number ≥ 2, and the rectangular piezoelectric ceramic is polarized in the thickness direction, and every two An electrode sheet is arranged between the piezoelectric ceramic sheets. The length of the piezoelectric crystal stack is greater than the distance between the middle mass block and the inner wall of the corresponding straight beam.

Further, the active driver is a round rod made of rare earth giant magnetostrictive material, a group of excitation coils are wound around the round rod, and the excitation coils are enclosed in a closed magnetic circuit made of high magnetic permeability material. The length of the round bar is greater than the distance between the intermediate mass and the inner wall of the corresponding straight beam.

The working principle of the present invention:

As shown in Figure 7, the dipole directivity is formed by the opposite phase vibration of the upper and lower radiating surfaces, and the monopole directivity or the in-phase '8' shape directivity is formed by using the in-phase vibration of the left and right two radiating surfaces, so that the four radiating surfaces The combined result is cardioid or super-directivity.

Claims (1)

1. The low-frequency directional underwater acoustic transducer is characterized in that: it comprises a radiation shell, four active drive units and an intermediate mass block, and the radiation shell is formed by alternately connecting four sections of curved beams and four sections of straight beams , the cross-sectional shape of the intermediate mass block is square and is located in the center of the radiation shell, four active drivers are respectively arranged between the four straight beams and the intermediate mass block, and the distance between the intermediate mass block and the corresponding straight beam less than the length of the active drive; The radiation shell is a three-concave and one-convex radiation shell or a three-convex and one concave radiation shell; The active driver is a piezoelectric crystal stack. The piezoelectric crystal stack is formed by bonding N pieces of rectangular piezoelectric ceramics, and N is an even number not less than 2. The rectangular piezoelectric ceramics are polarized along the thickness direction. An electrode sheet is arranged between the piezoelectric ceramic sheets; The active driver includes two transition blocks, a round bar made of rare earth giant magnetostrictive material arranged between the two transition blocks, and a permanent magnet sheet is arranged at the contact point between the round bar and the corresponding transition block. The block transition block is also provided with a coil bobbin, and the coil bobbin is wound with a coil.

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