Multi-point driving phase control bending plate low frequency transducer

Abstract

The application provides a multi-point driving amplitude-phase control bending plate low-frequency transducer, which comprises a radiation plate, driving vibrators and wedges. The radiation plate comprises a radiation flat plate, vertical blocks and vertical wedges. A plurality of vertical wedges and vertical blocks are oppositely arranged in pairs and fixed on one side of the radiation flat plate. The driving vibrators are made of elastic materials. One end of each driving vibrator is rigidly connected with the vertical block, and the other end is inserted between the vertical wedge and the wedge, and the wedge and the vertical wedge are fixed by bolts. Each vertical block and wedge compress and clamp the driving vibrator. The application utilizes two or more groups of driving vibrators to drive the amplitude-phase control, excite the vibration modes of various vibration modes and the vibration modes of various vibration mode combinations of the bending plate transducer, so that the high-efficiency sound radiation of the bending plate transducer is realized, and the application can be applied to the fields of super-long distance underwater acoustic detection and underwater acoustic communication.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of underwater acoustic transducers, and particularly relates to a multi-point driving amplitude-phase control bending plate low-frequency transducer. BACKGROUND

[0002] As the only information carrier that can propagate over long distances in the ocean, the propagation distance of acoustic waves varies with frequency. Low-frequency and ultra-low-frequency acoustic waves have small absorption loss in seawater and long propagation distance, so low-frequency and ultra-low-frequency underwater acoustic transducers are in urgent need in the technical fields of ultra-long-distance underwater acoustic detection, underwater acoustic countermeasure and underwater acoustic communication.

[0003] Due to the contradiction between the large structure size of low-frequency underwater acoustic transducers and the limited installation space of application platforms, low-frequency and small-size underwater acoustic transducers have become a research hotspot. Typical low-frequency transducers mainly include bending transducers, bending disc transducers, Helmholtz transducers, overflow ring transducers and electrodynamic transducers: the bending transducer and the bending disc transducer realize low-frequency emission by utilizing bending vibration with a relatively low resonant frequency; the Helmholtz transducer and the overflow ring transducer realize low-frequency emission by utilizing liquid cavity vibration with a relatively low resonant frequency. The resonant frequency of the electrodynamic transducer is independent of the overall size of the transducer, and is related to the mass of the movable part of the vibration system and the suspension spring stiffness, so by using a very flexible spring, the resonant frequency of the electrodynamic transducer can be set to the ultra-low frequency band below 100 Hz.

[0004] Among them, the working bandwidth of the bending transducer is not wide enough, which limits its use in some application scenarios with higher bandwidth requirements; when the working frequency reaches a frequency octave, the spatial distribution of acoustic radiation energy often has obvious directivity, making it difficult to achieve uniform sound field distribution in the whole space; and its working performance changes sensitively with underwater working depth, and additional adjustment or compensation may be needed at different depths.

[0005] The bending disc transducer has weak static water pressure resistance, especially when the working frequency drops to the order of several hundred hertz, its maximum working water depth decreases sharply, and if a larger working water depth is to be maintained at low frequency, the volume and weight will increase significantly, thereby losing the advantage of low-frequency small-size emission.

[0006] The Helmholtz transducer has a large difference in sending voltage between the transducer radiation head and the circumferential radiation port of the cylinder, and has obvious directivity. When using the circumferential radiation port of the cylinder for horizontal full-directional emission, the sound source level is low; and when using the radiation head for directional emission, the change in the posture of the transducer due to factors such as wind and current in the water will bring inconvenience to testing and use.

[0007] Overflow ring transducers are complex to manufacture, often involving a splicing process, which presents problems such as complex manufacturing, difficulty in ensuring consistency, and difficulty in repair. Although they have advantages in terms of small size and hydrostatic pressure resistance, they may have certain limitations in achieving extremely low frequencies, or achieving even lower frequencies may require larger dimensions.

[0008] Electric transducers have limited operating depth and generally require active or passive pressure compensation devices to balance the pressure between the air chamber and the outside environment. Their operating depth is generally within 200 meters. Increasing the volume of the air chamber to increase the operating depth makes it difficult for electric transducers to be adapted to small underwater platforms, thus limiting their application range. When using active compensation methods such as high-pressure gas cylinder compensation, there are problems with poor compensation accuracy, and the need to achieve gas source recycling results in a large increase in the size, weight, and power consumption of the entire device. Summary of the Invention

[0009] To overcome the shortcomings of existing transducers, this application proposes a multi-point driven amplitude-phase controlled bending plate low-frequency transducer, the transducer comprising:

[0010] Radiant panels include radiant flat plates, wedges, and blocks; among which,

[0011] The radiating plate has a plate structure;

[0012] The wedge is a flat plate with a right-angled trapezoidal cross-section;

[0013] The block is a rectangular flat plate;

[0014] Multiple wedges and blocks are fixed in pairs to one side of the radiating plate; the inclined side of the wedge is opposite to the block, and the end closer to the radiating plate is thicker.

[0015] A plurality of driving oscillators, including two cylindrical oscillators; the oscillators are made of elastic material; the number of driving oscillators, blocks, and wedges is the same;

[0016] A wedge is a flat plate with a right-angled trapezoidal cross-section.

[0017] One end of each of the driving oscillators is rigidly connected to the upright block, and the other end is inserted between the wedge and the upright wedge. When the wedge is inserted, the thinner end is inserted towards the radial plate, and its inclined surface is adjacent to the inclined surface of the upright wedge. The wedge and the upright wedge are fixed with bolts. Each of the upright blocks and the wedges compresses and clamps the driving oscillator.

[0018] As an improvement to the aforementioned transducer, the length of the driving oscillator is adjustable.

[0019] As an improvement to the above-mentioned transducer, the driving oscillator is a rare-earth type driving oscillator and / or a piezoelectric crystal stack type driving oscillator.

[0020] As an improvement to the above-mentioned transducer, the rare-earth type driving oscillator has a cylindrical oscillator made of rare-earth super magnetostrictive material; a metal coil is wound around the outside of the oscillator; two plate-shaped magnetic conductive blocks and the two oscillators form a closed magnetic circuit with an octagonal structure.

[0021] As an improvement to the above-mentioned transducer, the oscillator of the piezoelectric crystal stack type driving oscillator is a cylindrical piezoelectric crystal stack column; the piezoelectric crystal stack is formed by bonding N piezoelectric ceramic sheets, wherein N is an even number greater than or equal to 2; the piezoelectric ceramic sheets are polarized in the thickness direction; an electrode sheet is placed between every two piezoelectric ceramic sheets.

[0022] As an improvement to the above-mentioned transducer, the piezoelectric ceramic sheet is polygonal, circular, or elliptical.

[0023] As an improvement to the above-mentioned transducer, the radiating plate is a polygonal or curved edge plate with a uniform or variable thickness.

[0024] As an improvement to the aforementioned transducer, the amplitude and phase control means that the driving voltage amplitude of the driving oscillator located at different parts of the radiating plate is continuously adjustable.

[0025] As an improvement to the aforementioned transducer, the amplitude-phase control allows the phase difference of the driving voltage of the driving oscillator located at different parts of the radiating plate to be continuously adjustable within the range of 0° to 180°.

[0026] Compared with existing technologies, the advantages of this application are:

[0027] This application utilizes two or more sets of driving oscillators combined with multi-point driving amplitude and phase control to excite multiple vibration modes and combinations of multiple vibration modes in the bending plate transducer, thereby achieving high-efficiency acoustic radiation of the bending plate transducer, which can be applied to fields such as ultra-long-distance underwater acoustic detection and underwater acoustic communication. Attached Figure Description

[0028] Figure 1(a) shows a schematic diagram of the bending vibration principle implemented in this application;

[0029] Figure 1(b) shows a schematic diagram of the multi-point drive amplitude and phase control principle of this application.

[0030] Figure 2(a) shows the mode shape diagram of the multi-point driven amplitude-phase control of this application;

[0031] Figure 2(b) shows a schematic diagram of non-amplitude phase-controlled multi-point driving stress analysis;

[0032] Figure 2(c) shows the mode shape of the bent plate transducer under non-amplitude phase control conditions;

[0033] Figure 3 The diagram shows a multi-point driven amplitude-phase controlled bending plate low-frequency transducer structure with five groups of rare earth magnetostrictive materials driving oscillators to drive rectangular flat plates.

[0034] Figure 4 The diagram shows a schematic of a rare-earth magnetostrictive material driven oscillator structure.

[0035] Figure 5 The diagram shows a multi-point driven amplitude-phase controlled bending plate low-frequency transducer structure with 5 sets of piezoelectric crystal stacks driving oscillators to drive rectangular flat plates.

[0036] Figure 6 The diagram shows a piezoelectric crystal stack driven oscillator structure.

[0037] Figure 7 The diagram shows a multi-point driven amplitude-phase controlled bending plate low-frequency transducer structure with 8 sets of driving oscillators driving a circular flat plate.

[0038] Figure 8 The figure shows the test results of the response curves of the low-frequency transducer of the multi-point driven amplitude-phase controlled bending plate driven by the oscillator of the rare earth magnetostrictive material and the rectangular plate.

[0039] Figure 9 The image shows a multi-layered ring-shaped polygonal high-power sound source composed of a low-frequency transducer with multi-point driven amplitude and phase control bending plate.

[0040] Figure 10 The image shows a vertically mounted, polygonal, high-power sound source composed of a multi-point driven, phase-controlled, curved plate low-frequency transducer.

[0041] Attached image labels:

[0042] 1-Radiating plate, 2-Oscillator, 3-Wedge, 4-Piezoelectric crystal stack, 11-Standing block, 12-Standing wedge, 21-Magnetic guide block, 22-Rare earth super magnetostrictive rod, 23-Coil frame, 41-Electrode sheet, 42-Piezoelectric ceramic sheet Detailed Implementation

[0043] The technical solution of this application will be described in detail below with reference to the accompanying drawings.

[0044] Compared with other active materials, rare-earth giant magnetostrictive material Terfenol-D has the characteristics of large strain, high energy density, and low sound velocity due to magnetostriction. Therefore, underwater acoustic transducers using Terfenol-D as the driving material have a resonant frequency that is 30% to 50% lower than that of piezoelectric ceramic underwater acoustic transducers of the same size and structure, while the radiated sound power can be 5 to 10 times higher than that of piezoelectric ceramic underwater acoustic transducers. Therefore, this application uses rare-earth giant magnetostrictive material for transducer design.

[0045] This application proposes a multi-point driven amplitude and phase controlled bending plate low-frequency transducer. Based on the characteristic of low bending vibration frequency of large-size plate structures, the plate structure is selected as the radiating surface of the transducer. Multiple sets of driving oscillators are distributed at different positions on the radiating surface to form a bending plate transducer. An AC load is applied to the driving oscillators to generate longitudinal extension and contraction vibration, which is transmitted to the radiating plate through the vertical block and wedge structure to realize the bending vibration of the radiating plate. By controlling the driving voltage amplitude and phase of the multiple sets of driving oscillators, the transducer can be excited with multiple vibration modes and combinations of multiple vibration modes, thereby realizing the high-efficiency sound radiation of the bending plate transducer.

[0046] Example 1

[0047] A multi-point driven amplitude-phase controlled bending plate low-frequency transducer includes a radiating plate, a driving oscillator, and a wedge 3.

[0048] The radiant panel includes a radiant flat plate 1, a wedge 12, and a block 11.

[0049] The radiating plate 1 can be a rectangular plate, a hexagonal plate, or other polygonal thin plates, or a circular plate, an elliptical plate, or other thin plates with curved edges. The radiating plate 1 can be designed with constant thickness or variable thickness.

[0050] The wedge 12 and the block 11 are connected to the radiating plate 1 in pairs by screws of the same material and welded together, and fixed to the non-radiating side of the radiating plate 1.

[0051] Block 11 is a rectangular flat plate. Wedge 12 is a flat plate with a right-angled trapezoidal cross-section, thicker at the end near the radiating plate 1 and gradually thinning towards the distance from the radiating plate 1. Wedge 3 is a flat plate with a right-angled trapezoidal cross-section.

[0052] M (M≥2) driving oscillators are distributed at multiple points in the central and edge regions on the non-radiating side of the radiating plate 1. Each driving oscillator consists of 2 oscillators 2. The length of each set of oscillators 2 in the driving oscillator is adjustable.

[0053] The oscillator 2 is a cylindrical structure, which can be made of rare-earth super magnetostrictive material. The dynamic drive coil is set on the outside of the rare-earth cylinder to provide the driving magnetic field. The total length of the oscillator 2 is greater than the distance between the corresponding block 11 and the wedge 3 after the wedge 3 is inserted.

[0054] The oscillator 2 can be a piezoelectric crystal stack, which is composed of N rectangular piezoelectric ceramic sheets 42 bonded together, where N is an even number ≥ 2. The polygonal piezoelectric ceramic sheets 42 are polarized in the thickness direction, and an electrode sheet 41 is placed between every two piezoelectric ceramic sheets 42. The total length of the piezoelectric crystal stack is greater than the distance between the corresponding standing block 11 and the wedge 3 after the wedge 3 is inserted.

[0055] The driving oscillator may also include M1 group of rare earth super magnetostrictive rod driving oscillators and M2 group of piezoelectric crystal stacks (where M1+M2=M).

[0056] Each oscillator 2 is rigidly connected at one end to the upright block 11 and at the other end to the wedge 3. The wedge 3 is rigidly connected to the upright wedge 12. The wedge 3, inserted between the oscillator 2 and the upright wedge 12, provides prestress to the oscillator 2. The wedge 3, inserted into the upright wedge 12, forms a plane perpendicular to the radiating plate 1, and the wedge 3 and the upright wedge are fixed by bolts. The wedge 3 is installed simultaneously with the drive oscillator. A threaded hole is pre-drilled at the top of the upright wedge 12, and a through hole is pre-drilled at the end of the wedge 3 that mates with the upright wedge 12. Initially, the wedge 3 can only be inserted to a limited length between the oscillator 2 and the upright wedge 12; by gradually applying force with the bolts, the insertion length of the wedge 3 gradually increases until it is fully inserted. Amplitude and phase control refers to the continuous adjustment of the driving voltage amplitude of each drive oscillator located at different parts of the radiating plate, and the arbitrary adjustment of the phase difference of the driving voltage of each drive oscillator located at different parts of the radiating plate within the range of 0° to 180°.

[0057] As shown in Figure 1(a), the surface of the radiating plate furthest from the driving oscillator is defined as surface A, and the surface of the radiating plate closest to the driving oscillator is defined as surface B. When the driving oscillator performs contraction vibration, the area below the neutral plane of the radiating plate, i.e., surface B, undergoes contraction vibration along with the driving oscillator, while the area above the neutral plane, i.e., surface A, undergoes tensile vibration, resulting in bending vibration of the entire radiating plate. The driving voltage of the driving oscillator is... ,in For the driving voltage amplitude, This refers to the phase of the driving voltage.

[0058] This invention utilizes longitudinal vibration to drive an oscillator. When the oscillator is in contraction vibration, the side of the radiating plate 1 adjacent to the driving oscillator is in contraction vibration, and the side away from the driving oscillator is in extension vibration. Conversely, when the oscillator is in extension vibration, the side of the radiating plate 1 adjacent to the driving oscillator is in extension vibration, and the side away from the driving oscillator is in contraction vibration, thereby achieving bending vibration of the radiating plate 1.

[0059] As shown in Figure 1(b), a set of driving oscillators is used to drive the radiating plate 1. When the size of the radiating plate 1 is too large, the size of the driving oscillator must be increased accordingly. However, the actual size of the driving oscillator is limited. Using a multi-point driving method can reduce the requirements for the size of the driving oscillator. Secondly, in order to achieve low-frequency broadband transmission, it is necessary to excite multiple modes for multi-mode coupling. It is difficult to excite high-order modes by only one set of driving oscillators to excite the radiating plate 1. However, the multi-point driving method is convenient for exciting high-order modes.

[0060] Figures 2(a)-2(c) show the stress analysis diagram and mode shape diagram of the present invention. Figure 2(b) shows the stress analysis diagram of the bending plate transducer under multi-point driving amplitude and phase control. If the driving oscillator includes 3 sets of driving oscillators, one set of driving oscillators drives the main radiating part of the radiating plate 1 (the central region of the length direction of the radiating plate 1), and the remaining two sets of driving oscillators drive the secondary radiating part of the radiating plate 1 (the edge region of the length direction of the radiating plate 1) respectively: (1) If the 1# driving oscillator and the 2# driving oscillator vibrate in opposite phases; (2) When the 1# driving oscillator contracts and the 2# driving oscillator stretches, the B surface of the main radiating part undergoes contraction vibration and the A surface undergoes stretching vibration, the B surface of the secondary radiating part undergoes stretching vibration and the A surface undergoes contraction vibration; (3) In the part between the main radiation and the secondary radiation, the external force applied by the two sets of driving oscillators is in the same direction, and the stress acting on the cross section is continuous; (4) The bending vibration of the main radiating part and the secondary radiating part promotes each other, causing the amplitude of the entire radiating plate to increase; (5) For the second-order vibration mode of a rectangular thin plate, the main radiating part and the secondary radiating part undergo anti-phase bending vibration, and the three sets of driving oscillators are excited in opposite phases, which is beneficial to the excitation of its second-order vibration mode.

[0061] Figure 2(a) shows the mode shape of the bending plate transducer under multi-point drive amplitude and phase control: it includes 5 sets of drive oscillators, of which the main radiation part is equipped with 3 sets of drive oscillators and the secondary radiation part is equipped with 1 set of drive oscillators. When the drive oscillators of the main radiation part are all in phase and contract, the drive oscillators of the secondary radiation part are out of phase and perform tensile vibration. The vibration between each part of the radiation plate 1 is continuous, and the radiation plate 1 as a whole undergoes bending vibration. The vibration amplitude of the main radiation part is the largest.

[0062] In the case of non-amplitude and phase control, the stress analysis diagram and mode diagram are shown in Figure 2(b): (1) If the three sets of driving oscillators vibrate in phase, when the three sets of driving oscillators contract at the same time, the three parts of the B side of the radiation plate will all undergo contraction vibration, and the three parts of the A side of the radiation plate will all undergo tensile vibration; (2) In the part between the main radiation and the secondary radiation, the external forces applied by the two sets of driving oscillators are opposite in direction, and the stress acting on the cross section will cancel each other out, and the amplitude will decrease; (3) The bending vibrations of the main radiation part and the secondary radiation part inhibit each other, which will reduce the amplitude of the entire radiation plate; (4) For the second-order vibration mode of the rectangular thin plate, the main radiation part and the secondary radiation part undergo anti-phase bending vibration, and the three sets of driving oscillators are in phase, which is not conducive to the excitation of its second-order vibration mode.

[0063] Figure 2(c) shows the mode shape of the bending plate transducer under non-amplitude and phase control: when all driving oscillators contract in phase, the entire radiating plate is divided into 5 parts and undergoes bending vibration respectively. There are nodes between each part, and the maximum vibration amplitude is reduced.

[0064] Example 2

[0065] likeFigure 3 and Figure 4 As shown, in this embodiment, the oscillator 2 is made of a rare-earth super magnetostrictive material round bar 22, and the dynamic drive coil is wound on the coil frame 23 and disposed on the outside of the rare-earth round bar 22. The two single-bar oscillators 2 are mechanically connected in parallel through two magnetically conductive blocks 21 to form a closed magnetic circuit with a mouth-shaped structure. When an alternating current load is applied to the two sets of coils driving the oscillators, the two sets of rare-earth rods elongate or shorten at the same frequency, and through mechanical coupling with the upright block 11 and the wedge 3, the bending vibration of the radiating plate 1 is excited.

[0066] In this embodiment, there are 5 sets of driving oscillators. The total length of the oscillator 2 is greater than the distance between the corresponding upright block 11 and the wedge 3 after the wedge 3 is inserted. One end of the oscillator 2 is rigidly connected to the upright block 11, and the other end is adjacent to the upright wedge 12. The wedge 3 is inserted between the oscillator 2 and the upright wedge 12 and is rigidly connected to the oscillator 2.

[0067] In this embodiment, the five groups of driving oscillators are arranged from left to right, and the driving voltage amplitude is... The phases are 180°, 0°, 0°, 0°, and 180° respectively.

[0068] In this embodiment, the radiating plate adopts a uniform thickness design and is a rectangular thin plate made of titanium alloy. The wedge 3, wedge 12, and block 11 are made of titanium alloy, stainless steel, aluminum alloy, glass fiber, or carbon fiber.

[0069] In this embodiment, the multi-point driven amplitude-phase controlled bending plate low-frequency transducer can be either an air-backed type or an overflow type.

[0070] Example 3

[0071] like Figure 5 and Figure 6 As shown, the driving oscillator in this embodiment is a piezoelectric crystal stack 4. The piezoelectric crystal stack 4 is composed of N circular piezoelectric ceramic sheets 42 bonded together, where N is... The even number 2, circular piezoelectric ceramic sheets 42 are polarized in the thickness direction. An electrode sheet 41 is placed between every two piezoelectric ceramic sheets 42 for welding leads. The electrode sheet 41 is made of phosphor bronze. The piezoelectric ceramic sheets 42 are connected in parallel. The piezoelectric ceramic sheets 42 and the electrode sheet 41 are bonded alternately with epoxy resin to form a driving element. Each group of driving oscillators includes two piezoelectric crystal stacks. In other embodiments, the piezoelectric ceramic sheets 42 may also be elliptical.

[0072] In this embodiment, the driving oscillator can be made of piezoelectric crystal stacks, or other ferroelectric or antiferroelectric materials.

[0073] In this embodiment, the multiple sets of driving oscillators can be made of round bars and piezoelectric crystal stacks made of rare earth super magnetostrictive materials, respectively.

[0074] The rest of this embodiment is the same as that of Embodiment 1.

[0075] Example 4

[0076] like Figure 7 As shown, in this embodiment, the radiating plate 1 adopts a uniform thickness design and is a circular thin plate made of titanium alloy.

[0077] In this embodiment, the multiple sets of driving oscillators can be made of round bars and piezoelectric crystal stacks made of rare earth super magnetostrictive materials, or they can be made of round bars made of other ferroelectric or antiferroelectric materials and rare earth super magnetostrictive materials.

[0078] The rest of this embodiment is the same as that of Embodiment 1.

[0079] like Figure 8 The figure shown is a test graph of the main radiating surface direction response curve of the present invention. The solid line represents driving mode 2 (the driving voltage amplitude of all 5 groups of driving stacks is...). The response curves for all phases are 0°. The dashed line indicates the use of drive mode 1 (all 5 drive stacks have drive voltage amplitudes of 0°). The transducer response curves were obtained after phases of 180°, 0°, 0°, 0°, and 180°. The test results show that after amplitude and phase control, the overall response of the transducer corresponding to drive mode 1 is improved compared to drive mode 2.

[0080] Example 5

[0081] like Figure 9 As shown, the present invention uses the long side of the radiating plate 1 as the base to form a polygon along the circumferential direction and extend vertically along the short side of the radiating plate 1 to form a multi-layer ring polygonal high-power sound source.

[0082] Example 6

[0083] like Figure 10 As shown, the present invention uses the short side of the radiating plate 1 as the base to form a polygon along the circumferential direction, thus forming a vertical cylindrical polygonal high-power sound source.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of this application do not depart from the spirit and scope of the technical solutions of this application, and should all be covered within the scope of the claims of this application.

Claims

1. A multi-point driven amplitude-phase controlled bending plate low-frequency transducer, characterized in that, The transducer includes: Radiant panels include radiant flat plates, wedges, and blocks; among which, The radiating plate has a plate structure; The wedge is a flat plate with a right-angled trapezoidal cross-section; The block is a rectangular flat plate; Multiple wedges and blocks are fixed to one side of a radiating plate in pairs, with the inclined side of the wedge facing the block and the end closer to the radiating plate being thicker. A plurality of driving oscillators, including two cylindrical oscillators; the oscillators are made of an elastic material; the number of driving oscillators, blocks, and wedges are equal; and A wedge is a flat plate with a right-angled trapezoidal cross-section. One end of each driving vibrator is rigidly connected to the vertical block, and the other end is inserted between the vibrator and the wedge. When the wedge is inserted, the thinner end is inserted towards the radial plate, and its inclined surface is adjacent to the inclined surface of the wedge. The wedge and the wedge are fixed with bolts. Each vertical block and the wedge compress and clamp the driving vibrator. The amplitude and phase control means that the driving voltage amplitude of the driving oscillator located at different parts of the radiating plate is continuously adjustable.

2. The multi-point driven amplitude-phase controlled bending plate low-frequency transducer according to claim 1, characterized in that, The length of the driving oscillator is adjustable.

3. The multi-point driven amplitude-phase controlled bending plate low-frequency transducer according to claim 1 or 2, characterized in that, The driving oscillator is a rare-earth type driving oscillator and / or a piezoelectric crystal stack type driving oscillator.

4. The multi-point driven amplitude-phase controlled bending plate low-frequency transducer according to claim 3, characterized in that, The rare-earth type driving oscillator has a cylindrical oscillator made of rare-earth super magnetostrictive material; a metal coil is wound around the outside of the oscillator; two plate-shaped magnetic conductive blocks and the two oscillators form a closed magnetic circuit with an octagonal structure.

5. The multi-point driven amplitude-phase controlled bending plate low-frequency transducer according to claim 3, characterized in that, The oscillator of the piezoelectric crystal stack type driving oscillator is a cylindrical piezoelectric crystal stack column; the piezoelectric crystal stack is formed by bonding N piezoelectric ceramic sheets, where N is an even number greater than or equal to 2; the piezoelectric ceramic sheets are polarized in the thickness direction; an electrode sheet is placed between every two piezoelectric ceramic sheets.

6. The multi-point driven amplitude-phase controlled bending plate low-frequency transducer according to claim 5, characterized in that, The piezoelectric ceramic sheet is polygonal, circular, or elliptical.

7. The multi-point driven amplitude-phase controlled bending plate low-frequency transducer according to claim 1, characterized in that, The radiating plate is a polygonal or curved-edge plate with a thickness that is constant or variable.

8. The multi-point driven amplitude-phase controlled bending plate low-frequency transducer according to claim 1, characterized in that, The amplitude and phase control means that the phase difference of the driving voltage of the driving oscillator located at different parts of the radiating plate is continuously adjustable within the range of 0° to 180°.

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