A dual-mode coupled broadband capsule piezoelectric transducer

Abstract

The application discloses a bimodal coupling broadband capsule-shaped piezoelectric transducer, which comprises two piezoelectric half-spherical shells, piezoelectric circular tubes, a prestressed layer, a protective layer and a center positioning rod.

Description

TECHNICAL FIELD

[0001] The application relates to a piezoelectric transducer, in particular to a dual-mode coupled wideband capsule-shaped piezoelectric transducer, and belongs to the technical field of underwater acoustic transducers. BACKGROUND

[0002] With the development of small underwater platforms such as underwater unmanned vehicles, they are widely used in underwater target detection, underwater acoustic communication, underwater acoustic countermeasures, ocean geological exploration and ocean resource development. As the only information carrier that can be transmitted over long distances underwater, the demand for acoustic load on various small underwater platforms is increasing. However, due to the constraints of the carrying space, carrying weight, energy and installation size of small underwater platforms, the underwater acoustic transducer as the core wet end component of the acoustic load should not be too large in size and weight, the energy conversion efficiency should be as high as possible, and it should have good adaptability.

[0003] The acoustic load works in the medium frequency band of tens of kilohertz, and the piezoelectric transducer is one of the best choices. The conventional piezoelectric transducer usually adopts a spherical shell type, a circular tube type or a composite rod type. Such implementation has the advantages of mature technology, good universality and low cost.

[0004] The patent with the authorization announcement number CN112153543B provides a half-space radiation high-frequency wideband transducer, which comprises a piezoelectric ceramic spherical shell, an anti-sound barrier plate and a tuning circuit. The core of the patent is to use the sound barrier plate technology to realize the directivity control of the spherical shell transducer, so as to improve the directivity. Secondly, the method of setting the resonant circuit connected in series with the piezoelectric ceramic spherical shell is adopted to realize the purpose of widening the working frequency band of the underwater acoustic transducer.

[0005] The patent with the authorization announcement number CN102750941B provides a deep-water ultra-wideband spherical transducer, which comprises a piezoelectric ceramic ball, a water-tight layer, a perforated screw, a decoupling pipe, a cable head and a pressure-resistant shell. Similar to the CN112153543B patent, both of them widen the frequency band through the matching control of the circuit and the transducer at the circuit end (tuning circuit). The patent adopts an independent excitation method, respectively loads excitation voltage on the two ceramic balls, adjusts the amplitude and phase difference of the voltage, effectively excites the zero-order mode and all odd-order modes of the ceramic ball, and adjusts the amplitude and phase to control the response amplitude of each mode to expand the bandwidth of the transducer. In addition, unlike the CN112153543B patent, the pressure-resistant shell and the water-tight layer of the patent have the function of matching layer, which can further enrich the working mode of the transducer and facilitate the further expansion of the bandwidth of the transducer.

[0006] It can be seen that the matching of the circuit end to the circuit and the transducer for the operating bandwidth is a common technical means in the industry, and essentially still uses the breathing mode of the spherical shell transducer, and does not couple multiple modes from the transducer itself, and does not fully utilize the significant advantage of high electro-acoustic conversion efficiency near the resonance frequency. The mode introduced by the matching layer structure is relatively complex in transducer process, especially when vibrating greatly at high power, the adhesion reliability of the matching layer and the piezoelectric ceramic will be reduced.

[0007] The invention patent with the application publication number CN112530392A proposes a multi-modal wideband high-power executive emission longitudinal vibration underwater acoustic transducer, which includes a flexible ring longitudinal vibration transducer vibrator, a square cylindrical structure resonance cavity shell, a decoupling support structure and a tail sealing end cover. The flexible ring longitudinal vibration transducer vibrator is composed of a flexible ring front cover plate, a piezoelectric ceramic stack, a stress screw and a rear cover plate. This patent uses the liquid cavity coupling principle to design a square cylindrical structure liquid coupling cavity at the front end of the flexible ring longitudinal vibration transducer vibrator front cover plate, which will produce a new resonance peak between the two resonances of the double cover plate longitudinal vibration transducer. The difference between this patent and the patents CN112153543B and CN102750941B is that the transducer designed in this patent is a longitudinal vibration type composite rod transducer. Although this transducer can obtain a wider operating frequency band, the single element of the composite rod transducer has the disadvantage of narrow beam width, and the arrayed use has a complex structure, occupies a large space, and is easily limited by the arrayed form.

[0008] Therefore, how to fully utilize the high voltage response characteristics of the spherical transducer or its topological structure and develop a wideband underwater acoustic emission transducer with high transmission voltage response, wide operating frequency band, large power capacity, small size and light weight is the key to solving the above technical problems. SUMMARY

[0009] In view of the many defects and deficiencies in the above background art, the present invention improves and innovates, aiming to provide a dual-mode coupling wideband capsule-shaped piezoelectric transducer with high transmission voltage response, wide operating frequency band and large power capacity, which has significant advantages in operating frequency band, electro-acoustic conversion efficiency and power capacity, and can be used as an underwater acoustic load, or directly as a general underwater sound source.

[0010] Another object of the present invention is to improve the vibration transmission effect between the piezoelectric hemispherical shell and the piezoelectric circular tube, and effectively improve the large power sound emission capability of the transducer.

[0011] To solve the above problems and achieve the above invention purposes, the dual-mode coupling wideband capsule-shaped piezoelectric transducer of the present invention is realized by adopting the following design structure and adopting the following technical scheme:

[0012] A dual-mode coupling broadband capsule piezoelectric transducer, comprising:

[0013] Two piezoelectric hemispherical shells (1) arranged opposite to each other, both of which are coaxially provided with connecting holes;

[0014] A piezoelectric circular tube (2) connected between the two piezoelectric hemispherical shells (1) to form a capsule piezoelectric element;

[0015] A prestressed layer (3) wrapped on the outer surface of the capsule piezoelectric element;

[0016] A waterproof sound transmission layer (4) wrapped on the outer surface of the prestressed layer (3);

[0017] A center positioning rod (5) sequentially passing through the waterproof sound transmission layer (4) and the prestressed layer (3) at one end and connected to the connecting holes of the two piezoelectric hemispherical shells (1);

[0018] A watertight connector (6) connected to the open end of the waterproof sound transmission layer (4);

[0019] Wherein, the watertight connector (6) is electrically connected to one of the piezoelectric hemispherical shells (1) through the center positioning rod (5) and the lead wire (7); and each end of the piezoelectric circular tube (2) is further connected with a connecting piece (11) at the connecting position of the corresponding piezoelectric hemispherical shell (1).

[0020] Preferably, a vibration isolation pad (8) is further sleeved in the open end of the waterproof sound transmission layer (4), and the vibration isolation pad (8) is used for fixing the center positioning rod (5) at this end, wherein the center positioning rod (5) near the open end of the protective layer is sleeved in the vibration isolation pad (8).

[0021] Preferably, a fixing block (9) is further arranged at the connecting hole of the piezoelectric hemispherical shell away from the open end of the waterproof sound transmission layer (4), and the fixing block (9) is used for fixing the center positioning rod (5) at this end, wherein one end of the fixing block (9) is in contact with the inner wall of the waterproof sound transmission layer (4) at this end, and the other end of the fixing block (9) is located in the connecting hole of the piezoelectric hemispherical shell and the through hole of the prestressed layer.

[0022] Preferably, a center sleeve rod (10) is further connected to the open end of the waterproof sound transmission layer (4), and the center sleeve rod (10) is arranged between the waterproof sound transmission layer (4) and the watertight connector (6), one end of the center sleeve rod (10) is connected with the watertight connector (6) through a locking piece (12) and an O-shaped sealing ring (13);

[0023] The first connecting line (14) and the second connecting line (15) of the piezoelectric hemispherical shell (1) are respectively led out along the axial holes of the center positioning rod (5) and the center sleeve rod (10) to correspond to the connection of the wire (7) connected with the water-tight connector (6).

[0024] Preferably, the first connecting line (14) is led out from the outer wall of the piezoelectric hemispherical shell (1) at the opening end of the waterproof sound transmission layer (4) to be connected with the corresponding wire (7).

[0025] The second connecting line (15) is respectively connected with the third connecting line (16) on the inner wall of the piezoelectric hemispherical shell (1) at the opening end of the waterproof sound transmission layer (4), the fourth connecting line (17) on the inner wall of the piezoelectric hemispherical shell (1) away from the opening end of the waterproof sound transmission layer (4), and the fifth connecting line (18) on the inner wall of the piezoelectric circular tube (2).

[0026] Preferably, the piezoelectric hemispherical shell (1) is in a whole hemispherical structure, and the piezoelectric circular tube (2) is in a whole columnar structure with both ends open and an internal hollow.

[0027] The thickness of the piezoelectric hemispherical shell (1) and the piezoelectric circular tube (2) is equal.

[0028] The piezoelectric circular tube (2) and the two piezoelectric hemispherical shells (1) are bonded into a capsule-shaped piezoelectric element by an adhesive.

[0029] Preferably, the piezoelectric hemispherical shell (1) and the piezoelectric circular tube (2) are electrically connected in parallel, the piezoelectric hemispherical shell (1) and the piezoelectric circular tube (2) are both radially polarized, and the polarization directions are consistent, wherein the piezoelectric hemispherical shell (1) and the piezoelectric circular tube (2) are both "internal positive and external negative" or "internal negative and external positive".

[0030] Preferably, the prestressed layer (3) is formed by winding a fiber filament on the outside of the capsule-shaped piezoelectric element, wherein a cementing agent is coated on the surface of the prestressed layer (3), and the prestressed layer (3) at the connecting holes of the two piezoelectric hemispherical shells is in a continuous and unblocked state.

[0031] Preferably, the waterproof sound transmission layer (4) is in a whole capsule shape with one end open and the rest of the structure being completely closed, and the open end of the capsule shape extends outwardly by a hollow connecting part which is an integral forming structure with the capsule shape body, wherein the waterproof sound transmission layer (4) is made of sound transmission rubber, and the waterproof sound transmission layer (4) is used to realize the sound transmission and water-tightness of the capsule-shaped piezoelectric element.

[0032] Preferably, the center positioning rod (5) is in a columnar structure with both ends open and an internal hollow.

[0033] The center sleeve rod (10) and the center positioning rod (5) are fixedly connected or movably connected; wherein the contact position of the center sleeve rod (10) and the waterproof sound transmission layer (4) is a convex ring structure.

[0034] Working principle: before work, the capsule-shaped piezoelectric transducer can be directly used by being hung underwater, or be installed on an underwater unmanned underwater vehicle (13) as an acoustic load. When used for hanging, the operator connects the electrical connector (6) with the connecting interface of the hoisting device (20), and directly hangs the assembled capsule-shaped piezoelectric transducer underwater through the hoisting device (20), and receives and transmits signals through the hoisting device (20); when used as a load of the underwater unmanned underwater vehicle (19), the operator connects the watertight connector (6) with the connecting interface in the underwater unmanned underwater vehicle (19), then the operator tightly connects the capsule-shaped piezoelectric transducer at the mounting port of the underwater unmanned underwater vehicle (19) to form a whole, and after the underwater unmanned underwater vehicle (19) is put into water, the work can be carried out.

[0035] When working, based on the inverse piezoelectric effect of piezoelectric material, when an alternating current field is applied between the two poles of the capsule-shaped piezoelectric element, the structure of the piezoelectric element deforms, and the direction and size of the deformation change with the direction and size of the electric field, that is, the alternating current field excites the structure of the piezoelectric element to produce mechanical vibration, and through the medium covered in the capsule-shaped piezoelectric transducer, the medium is water or air, the water or air radiates sound waves outward. The double-mode coupled broadband capsule-shaped piezoelectric transducer belongs to a resonant transducer, and the working frequency band of this type of piezoelectric transducer is near the resonant frequency. The transducer works at the resonant frequency and near the resonant frequency by using an alternating current field, so that it has a higher electric-acoustic energy conversion efficiency; the overall structure of the capsule-shaped piezoelectric transducer is capsule-shaped, the modes of the piezoelectric hemispherical shell (1) and the piezoelectric circular tube (2) can be coupled, so that the transducer can fully utilize the two-order resonant frequency and improve the working bandwidth. The prestressed layer (3) can improve the equivalent tensile strength of the transducer when the capsule-shaped piezoelectric transducer is in a pressure state, thereby achieving the purpose of improving the power capacity of the transducer.

[0036] The beneficial effects generated by the present application compared with the prior art are:

[0037] 1. The present application proposes a capsule-shaped piezoelectric transducer scheme combining a piezoelectric spherical shell and a piezoelectric circular tube, which ingeniously couples the modes of the spherical shell and the circular tube. Compared with traditional spherical shell piezoelectric transducers and circular tube transducers, the present application has a wider -3dB working bandwidth and a higher sending voltage response, and has a significant advantage in electric-acoustic conversion efficiency.

[0038] 2. The present application provides a prestressed layer scheme for the capsule-shaped piezoelectric transducer, which can improve the vibration transmission effect between the piezoelectric hemispherical shell and the piezoelectric circular tube, and effectively improve the large-power sound emission capability of the transducer.

[0039] 3. The application provides a dual-mode coupled broadband capsule-shaped piezoelectric transducer with the advantages of wide working frequency band, high sending voltage response, small size, light weight, good adaptability and the like. BRIEF DESCRIPTION OF DRAWINGS

[0040] The specific embodiments of the application will be further described in detail below with reference to the accompanying drawings, in which:

[0041] Figure 1 is one of the use state diagrams of the application;

[0042] Figure 2 is the second use state diagram of the application;

[0043] Figure 3 is the third use state diagram of the application;

[0044] Figure 4 is the overall structure schematic diagram of the application;

[0045] Figure 5 is the cross-sectional schematic diagram of the application;

[0046] Figure 6 is the local cross-sectional schematic diagram of the application;

[0047] Figure 7 is the sending voltage response comparison curve of the application and the same radius spherical shell piezoelectric transducer;

[0048] Figure 8 is the first-order modal vibration mode cloud diagram of the application;

[0049] Figure 9 is the second-order modal vibration mode cloud diagram of the application;

[0050] In the drawings, the reference signs are as follows: 1-piezoelectric half spherical shell (1), 2-piezoelectric circular tube (2), 3-prestress layer (3), 4-waterproof sound transmission layer (4), 5-center positioning rod (5), 6-waterproof connector (6), 7-wire (7), 8-vibration isolation pad (8), 9-fixing block (9), 10-center sleeve rod (10), 11-connector (11), 12-locking piece (12), 13-O-shaped sealing ring (13), 14-first connecting wire (14), 15-second connecting wire (15), 16-third connecting wire (16), 17-fourth connecting wire (17), 18-fifth connecting wire (18), 19-underwater unmanned underwater vehicle (19), 20-hoisting equipment (20). DETAILED DESCRIPTION

[0051] In order to make the technical means, creative features, purposes and effects of the present application easy to understand, the technical solutions of the present application will be further described in detail below in combination with the drawings and specific embodiments. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and embodiments.

[0052] A dual-mode coupled broadband capsule-shaped piezoelectric transducer, comprising:

[0053] Two piezoelectric hemispherical shells 1 arranged opposite to each other, both of which are coaxially provided with connecting holes;

[0054] A piezoelectric circular tube 2 connected between the two piezoelectric hemispherical shells 1 to form a capsule-shaped piezoelectric element;

[0055] A prestressed layer 3 wrapped outside the surface of the capsule-shaped piezoelectric element;

[0056] A waterproof sound transmission layer 4 wrapped outside the surface of the prestressed layer 3;

[0057] A center positioning rod 5 sequentially passing through the waterproof sound transmission layer 4 and the prestressed layer 3 at one end and connected to the connecting holes of the two piezoelectric hemispherical shells 1;

[0058] A watertight connector 6 connected to the open end of the waterproof sound transmission layer 4;

[0059] Among them, the watertight connector 6 is electrically connected to one of the piezoelectric hemispherical shells 1 through the center positioning rod 5 inside and a lead wire 7; each end of the piezoelectric circular tube 2 is also connected with a connecting piece 11 at the connecting position of the corresponding piezoelectric hemispherical shell 1.

[0060] In the present application, the capsule-shaped piezoelectric transducer is connected with other driving circuit through the watertight connector 6; the capsule-shaped piezoelectric element can couple two-order vibration modes within the working frequency band, so that the capsule-shaped piezoelectric transducer has a broadband acoustic emission capability; the piezoelectric hemispherical shell 1 is provided with a connecting hole at the top end, the connecting hole of the piezoelectric hemispherical shell at one end of the capsule-shaped piezoelectric element is used to lead out the internal electrode, and the connecting hole of the piezoelectric hemispherical shell at the other end of the capsule-shaped piezoelectric element is used for positioning and fixing; the connecting piece 11 has conductivity.

[0061] Further, a vibration isolation pad 8 is also sleeved in the open end of the waterproof sound transmission layer 4, and the vibration isolation pad 8 is used to fix the center positioning rod 5 at this end, wherein the center positioning rod 5 close to the open end of the protective layer is sleeved in the vibration isolation pad 8.

[0062] In the present application, the waterproof sound transmission layer 4 is a waterproof sound transmission rubber layer with waterproof, sound transmission and anti-collision functions, the vibration isolation pad 8 is supported by a non-metallic material and has insulation and vibration isolation decoupling functions.

[0063] Further, a fixing block 9 is arranged at the connecting hole of the piezoelectric hemispherical shell away from the opening end of the waterproof sound transmission layer 4, and the fixing block 9 is used for fixing the center positioning rod 5 at the opening end, wherein one end of the fixing block 9 is in contact with the inner wall of the waterproof sound transmission layer 4 at the opening end, and the other end of the fixing block 9 is located in the connecting hole of the piezoelectric hemispherical shell and the through hole of the prestressed layer at the opening end.

[0064] In the present application, the fixing block 9 is made of insulating material, and the cross section of the fixing block 9 is T-shaped, and one end of the center positioning rod 5 is sleeved on the fixing block 9.

[0065] Further, a center sleeve rod 10 is connected at the opening end of the waterproof sound transmission layer 4, and the center sleeve rod 10 is arranged between the waterproof sound transmission layer 4 and the water-tight connector 6, and one end of the center sleeve rod 10 is connected with the water-tight connector 6 through a locking member 12 and an O-shaped sealing ring 13.

[0066] The first connecting line 14 and the second connecting line 15 of the piezoelectric hemispherical shell 1 are respectively connected with the corresponding conductive wire 7 through the axial holes of the center positioning rod 5 and the center sleeve rod 10.

[0067] In the present application, the locking member 12 is a screw, and the center sleeve rod 10 is fixed with the water-tight connector 6 by the screw, and the O-shaped sealing ring 13 realizes underwater sealing, and the first connecting line 14 and the second connecting line 15 of the piezoelectric hemispherical shell 1 are respectively connected with the corresponding conductive wire 7.

[0068] Further, the first connecting line 14 is led out from the outer wall of the piezoelectric hemispherical shell 1 at the opening end of the waterproof sound transmission layer 4 and connected with the corresponding conductive wire 7.

[0069] The second connecting line 15 is respectively connected with the third connecting line 16 on the inner wall of the piezoelectric hemispherical shell 1 at the opening end of the waterproof sound transmission layer 4, the fourth connecting line 17 on the inner wall of the piezoelectric hemispherical shell 1 away from the opening end of the waterproof sound transmission layer 4, and the fifth connecting line 18 on the inner wall of the piezoelectric circular tube 2.

[0070] Further, the piezoelectric hemispherical shell 1 is in a whole hemispherical structure, and the piezoelectric circular tube 2 is in a whole columnar structure with open ends and hollow inside.

[0071] The piezoelectric hemispherical shell 1 and the piezoelectric circular tube 2 have equal thickness.

[0072] The piezoelectric circular tube 2 and the two piezoelectric hemispherical shells 1 are bonded into a capsule-shaped piezoelectric element by an adhesive.

[0073] In the present application, the piezoelectric hemispherical shell 1 and the piezoelectric circular tube 2 have equal thickness, which can ensure the continuity of the structure of the capsule-shaped piezoelectric transducer and the vibration transmission thereof, and avoid the stress concentration problem at the bonding surface of the two.

[0074] Further, the piezoelectric hemispherical shell 1 and the piezoelectric circular tube 2 are electrically connected in parallel, the piezoelectric hemispherical shell 1 and the piezoelectric circular tube 2 are both radially polarized, and the polarization directions are consistent, wherein the piezoelectric hemispherical shell 1 and the piezoelectric circular tube 2 are both "internal positive and external negative" or "internal negative and external positive".

[0075] In the present application, the piezoelectric hemispherical shell 1 and the piezoelectric circular tube 2 are in an electrically parallel relationship, and due to the inverse piezoelectric effect of the material, the capsule-shaped piezoelectric element vibrates and radiates sound waves outward under the excitation of an electric signal; the capsule-shaped piezoelectric element can couple two-order vibration modes in the working frequency band, so that the capsule-shaped piezoelectric transducer has a wideband sound emission capability.

[0076] Further, the prestressed layer 3 is formed by winding a fiber filament on the outside of the capsule-shaped piezoelectric element, wherein a cementing agent is coated on the surface of the prestressed layer 3, and the prestressed layer 3 at the connecting holes of the two piezoelectric hemispherical shells is in a continuous and unblocked state.

[0077] In the present application, the prestressed layer 3 is used to provide prestress for the capsule-shaped piezoelectric element, improve the high-power sound emission capability of the transducer, and improve the vibration transmission effect between the piezoelectric hemispherical shell 1 and the piezoelectric circular tube 2.

[0078] The prestressed layer 3 is formed by winding a fiber filament, and epoxy resin cementing agent is coated on the surface of the fiber filament during winding and then solidified; the fiber filament is pre-tensioned according to the working requirements, and the material can be selected from glass fiber, carbon fiber, and metal wire.

[0079] Further, the waterproof sound-transparent layer 4 has a capsule shape with one open end and the rest of the structure being fully enclosed, and the open end of the capsule shape extends outwardly by a hollow connecting part which is integrally formed with the capsule-shaped body, wherein the waterproof sound-transparent layer 4 is made of sound-transparent rubber, and the waterproof sound-transparent layer 4 is used to realize the sound transmission and water tightness of the capsule-shaped piezoelectric element.

[0080] In the present application, the piezoelectric hemispherical shell connecting hole at the end of the fixing block 9 is fully enclosed by the waterproof sound-transparent layer 4, the open end of the waterproof sound-transparent layer 4 extends outwardly by a hollow cylindrical member for mounting the vibration isolation pad 8 and the center sleeve rod 10; the connecting part is used to mount the center positioning rod 5, the vibration isolation pad 8, and the center sleeve rod 10.

[0081] Further, the center positioning rod 5 has a columnar structure with both ends open and the inside hollow.

[0082] The center sleeve rod 10 and the center positioning rod 5 are fixedly connected or movably connected; wherein the contact position between the center sleeve rod 10 and the waterproof sound-transparent layer 4 is a convex ring-shaped structure.

[0083] In the application, the center positioning rod 5 is connected with the fixing block 9 at the connecting hole of the piezoelectric hemisphere shell 1 at the other end of the vibration isolation pad end through the connecting hole of the piezoelectric hemisphere shell 1 at the vibration isolation pad end;

[0084] The center positioning rod 5 passes through the opening of the waterproof sound transmission layer 4, and one end of the center positioning rod 5 is fixed with the capsule-shaped piezoelectric element through the fixing block 9, and the other end of the center positioning rod 5 passes through the vibration isolation pad 8; the center positioning rod 5 is a hollow structure, so that each connecting wire connected with the inner wall of the capsule-shaped piezoelectric element can pass through; the vibration isolation pad 8 is made of non-metallic material, and has the functions of vibration isolation and decoupling; the fixing block 9 is made of insulating material.

[0085] In the application, the fixed connection is adhesive connection or direct processing into an integrated structure, the movable connection is screw connection, bayonet connection, plug-in connection or bolt assembly connection; the center sleeve rod 10 and the center positioning rod 5 can be connected by mechanical connection such as screw thread or by adhesive connection;

[0086] The contact position of the center sleeve rod 10 and the waterproof sound transmission layer 4 is a convex ring structure, which can reduce the risk of insufficient insulation caused by water molecules penetrating into the capsule-shaped piezoelectric element along the contact surface of the sound transmission rubber and the structural member.

[0087] In summary, the more specific embodiment of the application is as follows:

[0088] The following provides a manufacturing step of the dual-mode coupling wideband capsule-shaped piezoelectric transducer of the application.

[0089] Step 1: forming the capsule-shaped piezoelectric element; as shown in the accompanying drawings, in step 1, the fourth connecting wire 17 is welded to the inner wall of the piezoelectric hemisphere shell 1 at the left end, the third connecting wire 16 is welded to the inner wall of the piezoelectric hemisphere shell 1 at the right end, and the fifth connecting wire 18 is welded to the inner wall of the piezoelectric circular tube 2; Figure 6 In step 2, after the surfaces of the piezoelectric hemisphere shells 1 at both ends and the piezoelectric circular tube 2 are cleaned by using anhydrous ethanol or acetone, the connecting end faces are coated with epoxy resin-based adhesive, and then the piezoelectric hemisphere shells 1 at both ends and the piezoelectric circular tube 2 are bonded after the epoxy resin-based adhesive is cured;

[0090] In step 3, the conductive connecting piece 11 is welded to the adjacent area of the outer wall of the piezoelectric hemisphere shell 1 at the left end and the piezoelectric circular tube 2, and the connecting piece 11 is welded to the adjacent area of the outer wall of the piezoelectric hemisphere shell 1 at the right end and the piezoelectric circular tube 2, so that the piezoelectric hemisphere shells 1 at both ends are connected in parallel with the outer wall electrode of the piezoelectric circular tube 2, the first connecting wire 14 is welded to the outer wall connecting hole near the right end of the piezoelectric hemisphere shell 1, the third connecting wire 16, the fourth connecting wire 17 and the fifth connecting wire 18 are connected in parallel, and then connected with the second connecting wire 15 to lead out, thereby forming the first connecting wire 14 and the second connecting wire 15 of the positive and negative electrodes of the capsule-shaped piezoelectric element;

[0091]

[0092] ​Step 2: Applying prestress to the capsule-shaped piezoelectric ceramic element. After fixing the capsule-shaped piezoelectric element fabricated in Step 1 to a specific fixture, clean the surface of the capsule-shaped piezoelectric element with anhydrous ethanol or acetone. Using a CNC prestress winding machine, set the tension of the winding fibers to ensure sufficient prestress is applied to the piezoelectric element. Wind the fibers onto the outer surface of the capsule-shaped piezoelectric element. During the winding process, apply an epoxy resin-based binder, and continue winding until the set number of layers is reached. After the epoxy resin-based binder cures and solidifies, prestress layer 3 is formed. This completes the process. Figure 6 The fabrication of the capsule-shaped piezoelectric element shown;

[0093] Step 3: Assembly of the capsule-shaped piezoelectric transducer. Step 1: Insert the central positioning rod 5 through the two connecting holes of the capsule-shaped piezoelectric element prepared in Step 2. The second connecting line 15, extending from the inner wall of the capsule-shaped piezoelectric element, passes through the inner cavity of the central positioning rod 5. Then, install the fixing block 9 to the non-second connecting line 15 leading end of the central positioning rod 5. Step 2: Insert the vibration isolation pad 8 onto the other end of the central positioning rod 5. The first connecting line 14, extending from the outer wall of the capsule-shaped piezoelectric element, passes through the circular hole on the cylindrical surface of the vibration isolation pad 8 and then exits through the inner cavity of the central positioning rod 5. Step 3: Coaxially install the central sleeve rod 10 with the central positioning rod 5. Then, extend the first connecting line 14 and the second connecting line 15, extending from the positive and negative poles of the capsule-shaped piezoelectric element, through the inner cavity of the central sleeve rod 10.

[0094] Step 4: Preparation of waterproof and sound-permeable layer 4. Clean the surface of the capsule-shaped piezoelectric transducer assembly structure completed in step 3 with anhydrous ethanol or acetone, then pour in JA-2S polyurethane rubber, place it in a constant temperature chamber at 80℃ for 24 hours to form a sound-permeable rubber layer, and then demold and clean it.

[0095] Step 5: Assembly of the capsule-shaped piezoelectric transducer. Step 1: Weld the first connecting wire 14 and the second connecting wire 15 to the corresponding connectors of the watertight connector 6 via the corresponding wires 7. Step 2: Clean the sealing surfaces of the watertight connector 6 and the central sleeve 10 with anhydrous ethanol, apply lubricating silicone grease, and then install the O-ring 13 on the sealing surface of the watertight connector 6. Step 3: After coaxially aligning the watertight connector 6 and the central sleeve 10, tighten the locking member 12 for a fixed connection.

[0096] During the entire implementation process described above, when in use, the operator uses the hoisting equipment 20 to hoist the prepared invention to the installation location of the underwater unmanned submersible 19. After the operator installs the outer wall, it can be used. Example 1

[0097] As attached Figure 8 and attached Figure 9 As shown, the outer diameters of both the piezoelectric hemispherical shell 1 and the piezoelectric circular tube 2 are 90 mm, and the length of the circular tube is 50 mm, for example. (See attached image.) Figure 8The mode shape cloud chart of the capsule-shaped piezoelectric transducer working at the first order resonant frequency is shown, and the mode shape has one node line located at the center of the piezoelectric circular tube 2. Figure 9 The mode shape cloud chart of the capsule-shaped piezoelectric transducer working at the second order resonant frequency is shown, and the mode shape has two node lines located at the center of the piezoelectric circular tube 2. Figure 8 And Figure 9 The two order resonant frequencies of the capsule-shaped piezoelectric transducer shown in the working frequency band correspond to the breathing mode of the capsule-shaped piezoelectric element, and have high electro-acoustic conversion efficiency.

[0098] Embodiment 2

[0099] As shown in the accompanying Figure 7 The outer diameter of the piezoelectric hemispherical shell 1 and the piezoelectric circular tube 2 is selected as 90 mm, and the length of the circular tube is selected as 50 mm. The sending voltage response curves of the ball shell transducer and the capsule-shaped transducer of the embodiment are compared. It can be seen from the comparison curves of the sending voltage response of the double-mode coupled wideband capsule-shaped piezoelectric transducer and the ball shell piezoelectric transducer with the same radius that the sending voltage response curve of the ball shell transducer is “single-peak”, and the peak value is located near 20 kHz frequency. The sending voltage response curve of the capsule-shaped piezoelectric transducer provided by the embodiment is “double-peak”, the first peak value is located near 16 kHz frequency, and the second peak value is located near 26 kHz frequency, which indicates that the capsule-shaped transducer provided by the embodiment can couple two order modes to work.

[0100] As shown in the accompanying Figure 7 As shown in the accompanying

[0101] In the description of the present specification, specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0102] In the entire implementation operation process described above, the double-mode coupled wideband capsule-shaped piezoelectric transducer provided by the embodiment includes a piezoelectric hemispherical shell 1, a piezoelectric circular tube 2, a prestressed layer 3, a waterproof sound transmission layer 4, a center positioning rod 5, a water-tight connector 6, a wire 7, a vibration isolation pad 8, a fixing block 9, a center sleeve rod 10, a connecting piece 11, a locking piece 12, an O-shaped sealing ring 13, a first connecting wire 14, a second connecting wire 15, a third connecting wire 16, a fourth connecting wire 17 and a fifth connecting wire 18. The two piezoelectric hemispherical shells 1 and the piezoelectric circular tube 2 are in an electrical parallel relationship. Due to the inverse piezoelectric effect of the material, the capsule-shaped piezoelectric element vibrates and radiates sound waves outward under the excitation of the electrical signal.

[0103] The application provides a dual-mode coupled wideband capsule-shaped piezoelectric transducer, which comprises two piezoelectric hemispherical shells 1 and a piezoelectric circular tube 2, and the core component is a capsule-shaped piezoelectric element obtained by bonding the two piezoelectric hemispherical shells 1 and the piezoelectric circular tube 2, and the outer surface of the capsule-shaped piezoelectric element is covered by a prestressed layer 3. The capsule-shaped piezoelectric element can couple two-order vibration modes in a working frequency band, so that the capsule-shaped piezoelectric transducer has a wideband acoustic emission capability; the piezoelectric hemispherical shells 1 and the piezoelectric circular tube 2 have equal thicknesses, so as to ensure the continuity of the structure of the capsule-shaped piezoelectric transducer and avoid stress concentration at the bonding surface of the two; the piezoelectric hemispherical shells 1 and the piezoelectric circular tube 2 are both polarized along the radial direction and have consistent polarization directions, i.e., both are 'internal positive and external negative' or 'internal negative and external positive'. A connecting hole is formed at the top of one piezoelectric hemispherical shell 1, which is used for leading out the internal electrode of the capsule-shaped piezoelectric element and facilitating the positioning and fixing of the capsule-shaped piezoelectric element. The prestressed layer 3 can provide prestress for the capsule-shaped piezoelectric element, improve the high-power acoustic emission capability of the transducer, and improve the vibration transmission effect between the piezoelectric hemispherical shells and the piezoelectric circular tube.

[0104] The central positioning rod 5 is located on the connecting hole of the two piezoelectric hemispherical shells 1, one end of the central positioning rod 5 is fixed on the capsule-shaped piezoelectric element through a fixing block 9, and the other end of the central positioning rod 5 is sleeved on a vibration isolation pad 8. The central positioning rod 5 has a hollow structure, so that the first connecting wire 14 and the second connecting wire 15 connected with the capsule-shaped piezoelectric element can pass through the central positioning rod 5 and then be connected with the corresponding lead wire 7; the lead wire 7 is connected with the water-tight connector 6 after passing through the central positioning rod 5 and a central sleeve rod 10; when the transducer works, the excitation electric signal is transmitted to the lead wire 7 through the water-tight connector 6, and then is loaded on the internal and external electrodes of the capsule-shaped piezoelectric transducer to drive the transducer to vibrate and emit sound; the fixing block 9 is made of non-conductive material; the vibration isolation pad 8 is made of non-metal material and has a vibration isolation and decoupling effect.

[0105] Finally, it should be noted that the above description is only a preferred embodiment of the application, and is not intended to limit the application in other forms. Any skilled person in the art can modify or change the above disclosed technical content to obtain equivalent embodiments. However, any simple modification, equivalent change and modification made on the basis of the technical essence of the application to the above embodiments still belongs to the protection scope of the technical solution of the application.

Claims

1. A dual-mode coupled broadband capsule-shaped piezoelectric transducer, characterized in that, include: The piezoelectric hemispherical shells (1) are arranged opposite each other, and both piezoelectric hemispherical shells (1) are coaxially provided with connecting holes; A piezoelectric tube (2) is connected between two piezoelectric hemispherical shells (1) to form a capsule-shaped piezoelectric element; Prestressed layer (3), the prestressed layer (3) is wrapped around the outer surface of the capsule-shaped piezoelectric element; A waterproof and sound-permeable layer (4) is wrapped around the outer surface of the prestressed layer (3); The central positioning rod (5) is a columnar structure with open ends and hollow interior. It passes through the waterproof and sound-permeable layer (4) and the prestressed layer (3) at one end and connects to the connection hole of the two piezoelectric hemispherical shells (1). Watertight connector (6) is connected to the opening end of the waterproof and sound-permeable layer (4); wherein the watertight connector (6) is electrically connected to one of the piezoelectric hemispherical shells (1) through the inside of the central positioning rod (5) via a wire (7); Each end of the piezoelectric tube (2) is connected to the corresponding piezoelectric hemispherical shell (1) with a connector (11). The prestressed layer (3) is formed by winding fiber filaments around the outside of the capsule-shaped piezoelectric element and is coated with adhesive on its surface. The prestressed layer (3) located at the connection hole of the two piezoelectric hemispherical shells (1) is in a connected and unclosed state. The piezoelectric hemispherical shell (1) and the piezoelectric circular tube (2) are electrically connected in parallel. Both the piezoelectric hemispherical shell (1) and the piezoelectric circular tube (2) are radially polarized and have the same polarization direction.

2. The dual-mode coupled broadband capsule-shaped piezoelectric transducer according to claim 1, characterized in that, A vibration isolation pad (8) is also sleeved inside the opening end of the waterproof and sound-permeable layer (4). The vibration isolation pad (8) is used to fix the central positioning rod (5) at that end. The central positioning rod (5) near the opening end of the waterproof and sound-permeable layer (4) is sleeved inside the vibration isolation pad (8).

3. The dual-mode coupled broadband capsule-shaped piezoelectric transducer according to claim 1, characterized in that, A fixing block (9) is also provided at the piezoelectric hemispherical shell connection hole away from the opening end of the waterproof and sound-permeable layer (4). The fixing block (9) is used to fix the center positioning rod (5) at this end. One end of the fixing block (9) is in contact with the inner wall of the waterproof and sound-permeable layer (4) at this end, and the other end of the fixing block (9) is located in the piezoelectric hemispherical shell connection hole and the through hole of the prestressed layer at this end.

4. A dual-mode coupled broadband capsule-shaped piezoelectric transducer according to claim 1, characterized in that, A central sleeve rod (10) is also connected to the open end of the waterproof and sound-permeable layer (4). The central sleeve rod (10) is located between the waterproof and sound-permeable layer (4) and the watertight connector (6). One end of the central sleeve rod (10) is connected to the watertight connector (6) through a locking member (12) and an O-ring seal (13). The first connecting line (14) and the second connecting line (15) of the piezoelectric hemispherical shell (1) are respectively led out along the shaft holes of the central positioning rod (5) and the central sleeve rod (10) and connected to the wire (7) connected to the watertight connector (6).

5. A dual-mode coupled broadband capsule-shaped piezoelectric transducer according to claim 4, characterized in that, The first connecting line (14) is led out from the outer wall of the piezoelectric hemispherical shell (1) at the opening end of the waterproof and sound-permeable layer (4) and connected to the corresponding wire (7); The second connecting line (15) is connected to the third connecting line (16) on the inner wall of the piezoelectric hemispherical shell (1) at the opening end of the waterproof and sound-permeable layer (4), the fourth connecting line (17) on the inner wall of the piezoelectric hemispherical shell (1) away from the opening end of the waterproof and sound-permeable layer (4), and the fifth connecting line (18) on the inner wall of the piezoelectric tube (2).

6. A dual-mode coupled broadband capsule-shaped piezoelectric transducer according to claim 1, characterized in that, The piezoelectric hemispherical shell (1) has an overall hemispherical structure; the piezoelectric cylindrical tube (2) has an overall columnar structure with open ends and a hollow interior; The piezoelectric hemispherical shell (1) and the piezoelectric circular tube (2) have the same thickness; Among them, the piezoelectric tube (2) and the two piezoelectric hemispherical shells (1) are bonded together with adhesive to form a capsule-shaped piezoelectric element.

7. A dual-mode coupled broadband capsule-shaped piezoelectric transducer according to claim 1, characterized in that, Both the piezoelectric hemispherical shell (1) and the piezoelectric circular tube (2) are "positive inside and negative outside" or "negative inside and positive outside".

8. A dual-mode coupled broadband capsule-shaped piezoelectric transducer according to claim 1, characterized in that, The waterproof and sound-permeable layer (4) is in the shape of a capsule with one end open and the rest of the structure fully enclosed. A hollow connecting part extends outward from the open end of the capsule shape. The hollow connecting part and the capsule shape body are integrally formed. The waterproof and sound-permeable layer (4) is made of sound-permeable rubber. The waterproof and sound-permeable layer (4) is used to achieve sound transmission and water tightness of the capsule-shaped piezoelectric element.

9. A dual-mode coupled broadband capsule-shaped piezoelectric transducer according to claim 4, characterized in that, The central positioning rod (5) is a columnar structure with openings at both ends and a hollow interior; The central sleeve rod (10) and the central positioning rod (5) are either fixedly connected or movably connected; wherein, The contact position between the central sleeve rod (10) and the waterproof and sound-permeable layer (4) is a raised ring structure.

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