CN108435523A - Droplet-shaped flextensional transducer - Google Patents

Abstract

The present invention provides a water drop type flexural transducer, which includes a water drop type radiation shell, a transition block and a driving element: the water drop type radiation shell is a shell of equal thickness, and the outside of the shell is composed of two equal short axes, different It is formed by splicing semi-ellipses with equal major axes, and the two ends of the shell are closed with cover plates. The driving element and the transition block form a vibrator assembly, and the vibrator assembly is placed on the equivalent long axis of the flexural shell, and is rigidly connected to two vertical end faces inside the shell. The invention utilizes the asymmetry of the shell structure to generate a first-order asymmetric bending mode, and utilizes the coupling of the first-order asymmetric bending mode and the first-order bending mode to expand the bandwidth of the bending-tension transducer. It can be used in underwater acoustic detection, countermeasures, communication, measurement and marine resource exploration and other fields.

Description

Water Drop Flextensional Transducer

technical field

The invention relates to an underwater acoustic transducer, in particular to a water drop type flexural transducer.

Background technique

As we all know, underwater communication mainly relies on sound waves, and instruments that can generate sound waves underwater are called transmitting transducers. Over the years, researchers have been working to improve the performance of transmitting transducers, and extending the broadband of the transducer is one of them.

The study of broadband transducers is of great significance. First, broadband transducers have advantages in signal transmission. Secondly, the transducer can transmit in broadband, so that the transmitted signal is not limited to a single product pulse, and frequency modulation signal can be considered. Especially for communication sonar, broadband transducers can increase the transmission rate of signals, improve the reliability and confidentiality of communication, and reduce the bit error rate.

There are three main methods to achieve broadband transmission from transducers.

For single-resonant working transducers, the bandwidth can be expanded by increasing the radiation resistance, reducing the structural mass and reducing the structural stiffness.

Combining two or more transducers with similar frequencies can obtain a broadband transmission response. Raymond Porzio (US) of Lockheed Martin Corporation of the United States proposed a slotted ring and rare earth longitudinal combined broadband transducer.

Multimodal coupling also enables broadband transmission of the transducer. Lan Yu from Harbin Engineering University designed and manufactured a double-shell flextensional transducer. Chen Si designed and manufactured a piezoelectric single crystal long-axis extended type IV flexural transducer.

Contents of the invention

The object of the present invention is to provide a water drop type flexural transducer, and expand the bandwidth of the flexural transducer through multi-mode coupling.

The purpose of the present invention is achieved in the following way: comprising a radiation shell and an array assembly, the radiation shell is a drop-shaped shell of equal thickness spliced by two semi-elliptical shells with equal minor axes and unequal major axes , the matrix assembly includes two transition blocks connected to the arc of the inner surface of the radiation shell, a driving element arranged between the two transition blocks, and an upper cover plate and a lower cover plate, and the connection between the upper cover plate and the lower cover plate is realized through the cooperation of threaded rod threads, a cable head and a hanging head are arranged on the upper cover plate, and at the joint of the upper cover plate and the radiation shell, the lower cover Backing plates are provided at the joints of the plates and the radiation shell.

The present invention also includes such structural features:

1. The drive element includes a PLZST antiferroelectric crystal stack, and the PLZST antiferroelectric crystal stack is formed by bonding N rectangular antiferroelectric ceramic sheets, wherein N is an even number ≥ 2, and every two antiferroelectric An electrode sheet is also arranged between the ferroelectric ceramic sheets.

2. The driving element includes a piezoelectric ceramic crystal pile, and the piezoelectric ceramic crystal pile is formed by bonding N pieces of rectangular piezoelectric ceramic sheets, wherein N is an even number ≥ 2, and every two piezoelectric ceramic sheets An electrode sheet is also provided.

3. The drive element includes a rare earth giant magnetostrictive rod, the rare earth giant magnetostrictive rod is covered with a coil frame, the coil frame is wound with a coil, and a permanent magnet sheet is respectively arranged at both ends of the rare earth giant magnetostrictive rod, The two permanent magnet pieces are connected with corresponding connection blocks.

Compared with the prior art, the beneficial effect of the present invention is: the present invention utilizes the asymmetrical elliptical shell structure of water drop type bending to generate the first-order asymmetric bending mode, and utilizes the first-order asymmetric bending mode and the first-order bending mode The coupling of the modes expands the bandwidth of the flextensional transducer. The water drop type flexural transducer of the present invention provides a novel transducer structural form of an asymmetrical flexural shell. The asymmetric flextensional shell structure makes the first-order asymmetric bending mode unable to completely cancel out the vibration effect, thus generating the first-order asymmetric bending mode. By adjusting the size of the asymmetric shell, the coupling of the first-order bending mode and the first-order asymmetric bending mode can be realized, thereby realizing the expansion of the bandwidth of the flextensional transducer. The water drop type flexural transducer of the present invention adopts the basic principle of the flexural transducer, so it has the advantages of low frequency, high power, small size and light weight. The water drop type flexural transducer of the invention can be applied to the fields of underwater acoustic detection, countermeasures, communication, measurement, marine resource exploration and the like.

Description of drawings

Fig. 1 is the plan view of the structure diagram of the water drop type flextensional transducer that uses antiferroelectric ceramics as the driving element in the present invention;

Fig. 2 is the measurement view of the water drop type flextensional transducer structure diagram that uses antiferroelectric ceramics as the driving element in the present invention;

Fig. 3 is the vibrator connection schematic diagram that uses antiferroelectric ceramics as the drive element in the present invention;

Fig. 4 is an isometric view of the overall shape of the drop-shaped flextensional transducer of the present invention;

Fig. 5 is the transmission voltage response simulation curve of the water drop type flexural transducer using antiferroelectric ceramics as the driving element in the present invention;

Fig. 6a and Fig. 6b are the directivity diagrams of the water drop type flexural transducer using antiferroelectric ceramics as the driving element in the corresponding frequencies of the first two modes respectively;

Fig. 7 is a schematic structural diagram of a drop-type flexural transducer using a rare earth giant magnetostrictive rod as a driving element in the present invention.

The meanings of the numbers in the attached drawings are: 1-water drop type radiation shell, 2-drive element, 3-transition block, 4-cover plate, 5-backing plate, 6-threaded rod, 7-nut, 8-cable, 9-cable head, 10-hanging head, 11-response peak corresponding to the first-order bending mode, 12-response peak corresponding to the first-order asymmetric bending mode, 13-coil bobbin, 14-permanent magnet, 15-rare earth super Magnetostrictive rod, 16-coil

Detailed ways

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

With reference to Fig. 1, Fig. 2, Fig. 3, make a droplet type flexural transducer of the present invention, comprise droplet type radiation housing, transition block and driving element, the outer edge of droplet type equal-thickness housing 1 is made of two etc. The minor axis and the semi-ellipse with unequal major axis are assembled together, all of which are processed by aluminum alloy materials. Both ends of the casing are sealed with cover plates; the driving element and the transition block form a vibrator assembly, which is placed on the equivalent long axis of the flexural casing and rigidly connected to the inner wall of the casing.

Preferably, the equivalent major axis of the drop-shaped flexural transducer of the present invention is 270 mm (the semi-major axis of the left ellipse is 172 mm, and the semi-major axis of the right ellipse is 98 mm), the common minor axis is 120 mm, the shell thickness is 14 mm, and the shell height is 90 mm .

The driving element and the transition block 3 form a vibrator assembly, and the transition block 3 is made of aluminum alloy. The longitudinal dimension of the vibrator assembly is slightly greater than or greater than the distance between the two vertical end faces in the direction of the long axis inside the shell. By pre-reducing the equivalent short axis of the drop-shaped radiation shell, the pressure generated by the growth of the equivalent long axis is utilized. The vibrator assembly is fixed between two vertical end surfaces inside the housing.

Preferably, the longitudinal dimension of the vibrator assembly is 0.32 mm larger than the distance between the two vertical end faces in the long axis direction inside the transducer housing. When assembling the transducer, by applying pressure to the equivalent short axis direction of the droplet-shaped radiation shell, the distance between the two vertical end faces in the long axis direction inside the shell is increased to make it larger than the longitudinal dimension of the vibrator assembly, and the vibrator The assembly is placed between the two vertical end faces and the pressure is released. At this time, the assembly is fixed between the two vertical end faces in the transducer shell by prestressing, and is rigidly connected with the transducer shell.

The transducer is closed with a cover plate 4, and a backing plate 5 is added between the cover plate 4 and the transducer housing to play the role of sealing and vibration isolation. The cover plate 4 is fastened to both ends of the transducer casing through threaded rods 6 and nuts 7 distributed outside the transducer casing, so that a closed air cavity is formed inside the transducer. The cover plate 4 is equipped with a cable head 9 and a hanging head 10 . In this embodiment, the backing plate 5 is made of silica gel plate with a thickness of 5mm, the cover plate 4 is made of aluminum alloy, and the threaded rod 6 is made of stainless steel.

The driving element 2 is made of 100 pieces of rectangular PLZST antiferroelectric ceramics. The size of the antiferroelectric ceramics is 30mm*30mm*1mm. The antiferroelectric vibrators are connected in parallel. The wiring is shown in Figure 2. A metal sheet of brass material is sandwiched between the antiferroelectric ceramic sheets to weld the lead wire. The size of the metal sheet is 30mm*30mm*0.1mm. The antiferroelectric ceramic sheet and metal sheet are bonded one by one with epoxy resin to form the driving element.

When the transducer is working, a DC bias electric field and an AC electric field are applied to the antiferroelectric vibrator through the cable 8. At this time, the antiferroelectric vibrator produces a periodic phase transition, which makes the overall antiferroelectric vibrator produce longitudinal stretching vibration, and the drive element and the shell The mechanical coupling of the body can excite different vibration modes of the shell in different frequency ranges, and the bandwidth expansion of the transducer can be realized by using the generated first-order bending mode and first-order asymmetric bending mode coupling.

The simulation curve of the transmitting voltage response of the transducer is shown in Fig. 5 . In Fig. 5, the first-order resonant peak 11 is produced by the first-order bending vibration of the transducer, and the resonant frequency is about 1260 Hz; the second-order resonant peak 12 is produced by the first-order asymmetric bending vibration of the transducer, and the resonant frequency is about 2220Hz. In the frequency range of 1.08kHz to 2.52kHz, the maximum transmission voltage response of the transducer is 149.1dB (reference level 0dB: 1pPa/V, at 1m), and the maximum response fluctuation is 6.4dB, which can realize the bandwidth expansion of the flextensional transducer .

The directivity diagrams of the first two modes of the transducer at corresponding frequencies are shown in Figure 6a and Figure 6b. At the frequency of 1260Hz corresponding to the first-order bending mode, the transducer is basically non-directional; at the frequency of 2220Hz corresponding to the first-order asymmetric bending mode, the transducer exhibits a "partial figure-of-eight" directivity characteristic.

The droplet-shaped radiation shell 1 and the transition block 3 of the present invention can be made of stainless steel, steel, titanium alloy, glass fiber or carbon fiber in addition to being made of aluminum alloy. In addition to being sealed with a cover plate, the water drop type flexural transducer can also adopt an overflow structure.

The driving element of the present invention includes a piezoelectric ceramic crystal pile, and the piezoelectric ceramic is formed by bonding N pieces of rectangular piezoelectric ceramic sheets, wherein N is an even number ≥ 2, and a piezoelectric ceramic sheet is placed between every two piezoelectric ceramic sheets. electrode sheet.

As shown in Figure 7, the driving element of the present invention adopts rare earth giant magnetostrictive rod 15, and the outside is covered with bobbin 13, and coil 16 is wound on the bobbin 13, and a piece of permanent magnetostrictive rod 15 two ends respectively is laid Magnetic sheet 14. The rare-earth giant magnetostrictive rod 15, the permanent magnet piece 14 and the transition block 3 form a vibrator assembly. The transducer assembly process of this embodiment is the same as that of Embodiment 1.

When the transducer is working, the rare-earth giant magnetostrictive rod 15 generates magnetostrictive vibration under the joint action of the static bias magnetic field provided by the permanent magnet piece 14 and the dynamic driving magnetic field generated after the coil 14 is energized. The mechanical coupling excites different vibration modes of the shell in different frequency ranges, and utilizes the generated first-order bending mode and first-order asymmetric bending mode coupling to realize broadband emission of the transducer.

The droplet-shaped radiation shell, transition block and cover plate can be made of stainless steel, steel, titanium alloy, aluminum alloy, glass fiber or carbon fiber.

To sum up, the present invention provides a water drop type flexural transducer. It includes a droplet-shaped radiant casing, a transition block and a driving element: the droplet-shaped radiant casing is a casing of equal thickness, and the outside of the casing is composed of two semi-ellipses with equal minor axes and unequal major axes. The ends are closed with cover plates. The driving element and the transition block form a vibrator assembly, which is placed on the equivalent long axis of the flexural housing and is rigidly connected to the two vertical end surfaces of the housing. The invention utilizes the asymmetry of the shell structure to generate a first-order asymmetric bending mode, and utilizes the coupling of the first-order asymmetric bending mode and the first-order bending mode to expand the bandwidth of the bending-tension transducer. It can be used in underwater acoustic detection, countermeasures, communication, measurement and marine resource exploration and other fields.

Claims (4)

1. The drop-shaped flextensional transducer is characterized in that: it includes a radiation shell and an array assembly, and the radiation shell is a drop-shaped splicing of two semi-elliptical shells with equal minor axes and unequal major axes. The equal-thickness shell, the matrix assembly includes two transition blocks connected to the arc of the inner surface of the radiant shell, a driving element arranged between the two transition blocks, and the upper and lower ends of the radiant shell are respectively provided with The upper cover and the lower cover, and the connection between the upper cover and the lower cover is realized through the cooperation of threaded rod threads, a cable head and a hanging head are arranged on the upper cover, and the connection between the upper cover and the radiation shell A backing plate is provided at the joint and the joint between the lower cover plate and the radiation shell. 2. The drop-type flexural transducer according to claim 1, characterized in that: the driving element comprises a PLZST antiferroelectric crystal stack, and the PLZST antiferroelectric crystal stack is made of N rectangular antiferroelectric ceramics The antiferroelectric ceramic sheets are bonded together, where N is an even number ≥ 2, and an electrode sheet is arranged between every two antiferroelectric ceramic sheets. 3. The drop-shaped flextensional transducer according to claim 1, wherein the driving element comprises a piezoelectric ceramic crystal pile, and the piezoelectric ceramic crystal pile is formed by bonding N pieces of rectangular piezoelectric ceramic sheets , where N is an even number ≥ 2, and an electrode sheet is arranged between every two piezoelectric ceramic sheets. 4. The drop-type flexural transducer according to claim 1, characterized in that: the driving element comprises a rare earth giant magnetostrictive rod, and the rare earth giant magnetostrictive rod is covered with a coil bobbin, and the coil bobbin is wound There is a coil, and a permanent magnet sheet is arranged at both ends of the rare earth giant magnetostrictive rod, and the two permanent magnet sheets are connected with corresponding connecting blocks.