A single-ended excitation broadband transducer

Abstract

This invention discloses a single-ended excitation broadband transducer, comprising a front cover plate, a transducer drive element, and a rear cover plate sequentially fixedly connected by prestressed screws. The transducer drive element includes a piezoelectric ceramic drive crystal stack and a metal resonant structure arranged sequentially along the axial direction. The length of the piezoelectric ceramic drive crystal stack is one-quarter of its first-order longitudinal vibration wavelength; the length of the metal resonant structure is one-quarter of its first-order longitudinal vibration wavelength, and the longitudinal vibration resonant frequencies of the piezoelectric ceramic drive crystal stack and the metal resonant structure are the same. Because the transducer drive element of this invention includes a piezoelectric ceramic drive crystal stack and a metal resonant structure arranged sequentially along the transducer's axial direction, the transducer can still achieve full excitation of the first three longitudinal vibration modes, making the transducer's emission voltage response tend to be flat within the target frequency band. At the same time, it reduces the use of the piezoelectric ceramic drive crystal stack, avoiding waste and reducing manufacturing costs.

Description

Technical Field

[0001] This invention relates to the field of underwater acoustic transducer technology, and in particular to a single-ended excitation broadband transducer. Background Technology

[0002] Underwater acoustic transducers (longitudinal vibration transducers) are devices that convert underwater electroacoustic energy. With the rapid development of modern sonar technology and the continuous expansion of underwater acoustic applications, the performance requirements for underwater acoustic transducers are becoming increasingly stringent. In the field of underwater acoustic transducers, the bandwidth of single-resonant transducers is insufficient to meet the application requirements for broadband signals in underwater acoustics. Furthermore, broadband transducers are also needed in military fields, underwater acoustic measurement, marine surveying, and medical applications. Broadband transducers can maintain signal integrity and accuracy, ensuring distortion-free signal transmission, increasing signal transmission rate, and reducing bit error rate. To enable composite rod transducers to perform broadband acoustic emission, composite rod transducers using the single-ended excitation principle have emerged. Single-ended excitation is a technique for modal modulation of piezoelectric ceramic driven crystal stacks. Its core is to apply a composite electrical signal to the piezoelectric ceramic driven crystal stack, simultaneously exciting both odd-order and even-order longitudinal vibration modes, ultimately optimizing the device's operating bandwidth and response stability. The piezoelectric ceramic driving stack is divided into two equal-volume upper and lower sections along the longitudinal vibration direction, and the upper and lower sections are symmetrical about the geometric center. Under single-ended excitation technology, the piezoelectric ceramic in the lower half is subjected to voltage, while the piezoelectric ceramic in the upper half is not subjected to voltage. This situation results in the waste of the piezoelectric ceramic as an active material. Summary of the Invention

[0003] To address the aforementioned problems, this invention proposes a single-ended excitation broadband transducer.

[0004] A single-ended excitation broadband transducer includes a front cover plate, a transducer driving element, a rear cover plate, and a prestressed screw. The front cover plate, the transducer driving element, and the rear cover plate are arranged sequentially. The rear cover plate and the transducer driving element are passed through by the prestressed screw and fixedly connected to the front cover plate. The transducer driving element includes a piezoelectric ceramic driving crystal stack and a metal resonant structure arranged sequentially along the axial direction of the transducer. One end of the piezoelectric ceramic driving crystal stack and one end of the metal resonant structure are bonded together, and the other end is connected to one side of the rear cover plate.

[0005] The length of the piezoelectric ceramic driven crystal stack as follows:

[0006] (1)

[0007] in, This represents the longitudinal wave velocity of the piezoelectric ceramic driven crystal stack. This represents the first-order longitudinal vibration resonant frequency of the piezoelectric ceramic driven crystal stack;

[0008] The cross-section of the metal resonant structure is consistent with the cross-section of the piezoelectric ceramic driving crystal stack, and the length of the metal resonant structure is... as follows:

[0009] (2)

[0010] in, The longitudinal wave velocity of a metallic resonant structure. This represents the first-order longitudinal resonant frequency of a metallic resonant structure. and Consistent.

[0011] Furthermore, the metal resonant structure is a metal rod-shaped structure.

[0012] Furthermore, the metal rod-shaped structure is also provided with weight-reducing holes arranged in the axial direction.

[0013] Furthermore, the weight-reducing holes are elongated holes that extend along the axial direction of the metal rod-shaped structure and have a circular cross-section, and the plurality of weight-reducing holes are evenly distributed in a ring on the cross-section of the metal rod-shaped structure.

[0014] Furthermore, the metal rod-shaped structure is made of duralumin.

[0015] Furthermore, the piezoelectric ceramic driving crystal stack includes an even number of piezoelectric ceramic ring plates and an odd number of metal ring plates, the piezoelectric ceramic ring plates and the metal ring plates are alternately bonded together, the polarization directions of adjacent piezoelectric ceramic ring plates are opposite, and wires are welded on the metal ring plates.

[0016] Furthermore, the front cover is made of hard aluminum, and the shape of the front cover is a trumpet-shaped structure that gradually increases from one end in contact with the metal resonant structure to the other end; the rear cover is made of brass.

[0017] Furthermore, it also includes a metal sleeve, in which the transducer drive element, the rear cover plate, and the prestressed screw are placed. The metal sleeve is provided with a vibration isolation structure, and the other end of the metal sleeve is watertightly fixedly connected to the front cover plate.

[0018] Compared with the prior art, the single-ended excitation broadband transducer disclosed in this invention has the following advantages:

[0019] The single-ended excitation broadband transducer disclosed in this invention includes a piezoelectric ceramic driving crystal stack and a metal resonant structure arranged sequentially along the axial direction of the transducer. This allows the transducer to achieve full excitation of the first three longitudinal vibration modes while making the transducer's emission voltage response tend to be flat in the target frequency band. At the same time, it reduces the use of piezoelectric ceramic driving crystal stacks, avoids waste of piezoelectric ceramic driving crystal stacks, and reduces manufacturing costs. Attached Figure Description

[0020] Figure 1 The electrification methods and mode shapes of odd-order longitudinal vibrations in existing piezoelectric ceramic stacks;

[0021] Figure 2 The even-order longitudinal vibrations of existing piezoelectric ceramic stacks are energized and their mode shapes are described.

[0022] Figure 3 This refers to the energizing method under single-end excitation of piezoelectric ceramic stacks;

[0023] Figure 4 In order to adopt Figure 3 State diagram after superposition of medium-voltage electric ceramic crystal stacks with energizing methods;

[0024] Figure 5 The results show the transmitter voltage response of the transducer under different power-on conditions;

[0025] Figure 6 This is a structural diagram of the single-ended excitation broadband transducer disclosed in this invention;

[0026] Figure 7 This is a structural diagram of the transducer drive element in the single-ended excitation broadband transducer disclosed in this invention;

[0027] Figure 8 This is a structural diagram of one embodiment of the metal resonant structure of the transducer drive element in the single-ended excitation broadband transducer disclosed in this invention.

[0028] Figure 9 This invention presents the first three longitudinal vibration modes of the transduction drive element (all piezoelectric ceramic drive stacks) of an existing single-ended excitation broadband transducer.

[0029] Figure 10 The present invention presents the results of the first three longitudinal vibration modes of the transduction drive element (using piezoelectric ceramic drive stack and metal resonant structure) of the single-ended excitation broadband transducer disclosed in this application using finite element analysis.

[0030] Figure 11 The present invention relates to the underwater emission voltage response results of the single-ended excitation broadband transducer disclosed in this application;

[0031] Figure 12This is a structural diagram of another embodiment of the metal resonant structure of the transducer drive element in the single-ended excitation broadband transducer disclosed in this invention;

[0032] Figure 13 for Figure 12 Top view of a medium-sized metal resonant structure;

[0033] In the figure: 1. Front cover plate; 2. Transducer drive element; 20. Piezoelectric ceramic drive crystal stack; 21. Metal resonant structure; 200. Piezoelectric ceramic ring plate; 201. Metal ring plate; 210. Weight reduction hole; 3. Rear cover plate; 4. Prestressed screw; 5. Central through hole. Detailed Implementation

[0034] Existing underwater acoustic transducers (longitudinal vibration transducers) generally include a front cover plate, a rear cover plate, a transducer driving element composed of a piezoelectric ceramic driving crystal stack, and a prestressed screw. The front cover plate, the piezoelectric ceramic driving crystal stack, and the rear cover plate are arranged in sequence. The rear cover plate, the piezoelectric ceramic driving crystal stack, and the front cover plate are fastened together by the prestressed screw. A resonant beam is generated by applying a voltage to the piezoelectric ceramic driving crystal stack, and then emitted through the front cover plate.

[0035] like Figure 1 As shown in Figure (a), conventional longitudinal vibration transducers use piezoelectric ceramic drive stacks as the transduction driving element. Typically, in a parallel configuration, the piezoelectric ceramic drive stacks are divided into two equal-volume upper and lower sections along the longitudinal vibration direction. These sections are symmetrical about their geometric centers. For a pair of adjacent slender piezoelectric ceramic drive stacks with opposite polarization directions, each piezoelectric ceramic sheet is glued together using a mechanical series connection and a parallel electrical connection. When a harmonic AC voltage V is applied, this piezoelectric ceramic drive stack will produce a stretching or contracting motion. Figure 1 The arrows in Figure (a) represent the polarization direction of each piezoelectric ceramic piece. Figure 1 Figure (b) illustrates the intuitive motion of the first-order longitudinal vibration of the piezoelectric ceramic driven crystal stack. The arrows in the figure indicate the direction of motion. The upper and lower halves of the piezoelectric ceramic driven crystal stack exhibit in-phase stretching motion. Figure 1 Figure (c) illustrates the intuitive motion of the third-order longitudinal vibration of a piezoelectric ceramic driven crystal stack. The arrows indicate the direction of motion. The piezoelectric ceramic driven crystal stack is divided into three parts: the upper and lower parts are contracting, and the middle part is expanding. The upper and lower halves of the piezoelectric ceramic driven crystal stack still exhibit symmetrical motion. In-phase excitation (electrical signals in phase) of the upper and lower partitions drives synchronous expansion and contraction of the partitions. Due to electrical symmetry, only odd-order longitudinal vibration modes with symmetrical displacement field distribution can be excited. Even-order longitudinal modes are suppressed due to displacement symmetry mismatch. Therefore... Figure 1 The power supply method shown in Figure (a) can only excite first-order and third-order longitudinal vibrations.

[0036] like Figure 2 As shown in Figure (a), if a stack of two adjacent elongated piezoelectric ceramic driving crystals with opposite polarization directions (where each piezoelectric ceramic sheet is glued together by mechanical series connection and parallel electrical terminals) is subjected to a harmonic AC voltage -V on the upper half of the ceramic and a harmonic AC voltage +V on the lower half, even-order longitudinal vibration modes can be excited through mechanical coupling of partitioned inverse phase stretching, exhibiting the following characteristics: Figure 2 The second-order longitudinal vibration of the piezoelectric ceramic-driven crystal stack is shown in Figure (b). The arrows in the figure indicate the direction of motion. The upper half of the piezoelectric ceramic-driven crystal stack expands, while the lower half undergoes an opposite contraction motion.

[0037] like Figure 3 As shown, if we take Figure 1 The power-on method in Figure (a) and Figure 2 The superposition of the energizing methods shown in Figure (a) can simultaneously excite the first, second, and third order longitudinal vibrations of the piezoelectric ceramic driven crystal stack. The energizing methods are as follows: Figure 3 As shown, this power-on method is the single-ended excitation power-on method. The power-on method of the piezoelectric ceramic driven crystal stack in this way is as follows: Figure 4 As shown.

[0038] Single-ended excitation, through the superposition of in-phase and out-of-phase excitations, can simultaneously induce the first, second, and third order longitudinal vibrations of the piezoelectric ceramic driven crystal stack, such as... Figure 5 As shown, this can make the transducer's transmit voltage response flatten within the target frequency band, ultimately achieving effective bandwidth expansion.

[0039] exist Figure 5 As shown in Figure (a), curve a represents the emission voltage response under symmetrical excitation of the piezoelectric ceramic driven stack. The transducer can only excite the first and third order longitudinal vibrations; the even-order longitudinal modes are suppressed due to displacement symmetry mismatch, manifested as a sharp drop in the end-face displacement amplitude at the resonant frequency of the second order longitudinal mode, corresponding to a deep valley in the emission voltage response curve. However, by using a single-end excitation method—a superposition of in-phase and out-of-phase excitations—to energize the piezoelectric ceramic driven stack, the transducer can excite the first, second, and third order longitudinal vibrations, as shown in Figure (a). Figure 5 As shown in Figure (b), the transducer's transmit voltage response is made to flatten within the target frequency band (curve c), ultimately achieving effective bandwidth expansion.

[0040] However, as Figure 3 As shown, the superposition of in-phase and out-of-phase excitations causes the piezoelectric ceramic driving crystal stack in the lower half of the partition to be subjected to voltage, while the piezoelectric ceramic driving crystal stack in the upper half of the partition is not subjected to voltage. This situation results in the waste of the piezoelectric ceramic driving crystal stack as an active material.

[0041] like Figure 6and Figure 7 As shown, the single-ended excitation broadband transducer disclosed in this invention includes a front cover plate 1, a transducer driving element 2, a rear cover plate 3, and a prestressed screw 4. The front cover plate 1, the transducer driving element 2, and the rear cover plate 3 are arranged sequentially. The rear cover plate 3 and the transducer driving element 2 are passed through by the prestressed screw 4 and fixedly connected to the front cover plate 1. The transducer driving element 2 includes a piezoelectric ceramic driving crystal stack 20 and a metal resonant structure 21 arranged sequentially along the axial direction of the transducer. One end of the piezoelectric ceramic driving crystal stack 20 and one end of the metal resonant structure 21 are bonded together, and the other end is connected to one side of the rear cover plate 3.

[0042] The length of the piezoelectric ceramic driven crystal stack as follows:

[0043] (1)

[0044] in, This represents the longitudinal wave velocity of the piezoelectric ceramic driven crystal stack. This represents the first-order longitudinal vibration resonant frequency of the piezoelectric ceramic driven crystal stack;

[0045] The cross-section of the metal resonant structure is consistent with the cross-section of the piezoelectric ceramic driving crystal stack, and the length of the metal resonant structure is... as follows:

[0046] (2)

[0047] in, The longitudinal wave velocity of a metallic resonant structure. This represents the first-order longitudinal resonant frequency of a metallic resonant structure. and Consistent.

[0048] Specifically, such as Figure 6 and Figure 7As shown, the single-ended excitation broadband transducer disclosed in this invention includes a front cover plate 1, a transducer driving element 2, a rear cover plate 3, and a prestressed screw 4. The front cover plate 1 is a trumpet-shaped structure with its radial dimension gradually increasing from one end to the other. The small-diameter end of the front cover plate 1 is provided with a threaded hole. The rear cover plate 3 is a disc-shaped structure with a central through hole. The transducer driving element 2 is provided between the front cover plate 1 and the rear cover plate 3. The transducer driving element 2 includes a piezoelectric ceramic driving crystal stack 20 and a metal resonant structure 21. The piezoelectric ceramic driving crystal stack 20 and the metal resonant structure 21 are arranged along the axial direction of the transducer. The piezoelectric ceramic driving crystal stack includes an even number of piezoelectric ceramic ring plates and an odd number of metal ring plates. The piezoelectric ceramic rings are bonded together alternately, with the polarization directions of adjacent piezoelectric ceramic rings being opposite. The metal rings serve as electrodes for applying voltage to the piezoelectric ceramic rings. Wires are welded onto the metal rings. Generally, thin copper rings are used for the metal rings. The piezoelectric ceramic driving crystal stack 20 and the metal resonant structure 21 are also provided with central through holes 5. The prestressed screw 4 passes through the central through holes on the rear cover plate 3, the piezoelectric ceramic driving crystal stack 20, and the metal resonant structure 21 in sequence from one end of the rear cover plate 3, and is then tightened and fixed to the front cover plate 1. At the same time, the contact surfaces between the front cover plate and the metal resonant structure, the metal resonant structure and the piezoelectric ceramic driving crystal stack, and the piezoelectric ceramic driving crystal stack and the rear cover plate are all coated with epoxy resin for bonding.

[0049] Length of piezoelectric ceramic driven stack as follows:

[0050] (1)

[0051] in, This represents the longitudinal wave velocity of the piezoelectric ceramic driven crystal stack. This represents the first-order longitudinal vibration resonant frequency of the piezoelectric ceramic driven crystal stack;

[0052] The cross-section of the metal resonant structure is consistent with the cross-section of the piezoelectric ceramic driven crystal stack, and the length of the metal resonant structure is... as follows:

[0053] (2)

[0054] in, The longitudinal wave velocity of a metallic resonant structure. This represents the first-order longitudinal resonant frequency of a metallic resonant structure. and Consistent. The single-ended excitation broadband transducer disclosed in this application has a transducer driving element comprising a piezoelectric ceramic driving crystal stack and a metal resonant structure arranged sequentially along the axial direction of the transducer, and the length of the piezoelectric ceramic driving crystal stack is... The length of the metal resonant structure This results in the length of the slender rod-shaped transducer driven element, composed of a piezoelectric ceramic driving crystal stack and a metal resonant structure, being (or close to) half the wavelength of its first-order longitudinal vibration. In other words, the length of the slender rod-shaped transducer driven element is equal to or approximately equal to... λ / 2, λ To achieve the first-order longitudinal vibration wavelength of the transducer driving element, a single-ended excitation voltage is applied to the piezoelectric ceramic driving crystal stack. This allows the transducer to achieve full excitation of the first three longitudinal vibration modes while making the transducer's emission voltage response flat within the target frequency band. At the same time, it reduces the amount of piezoelectric ceramic driving crystal stack used. Specifically, this application replaces the upper half of the piezoelectric ceramic driving crystal stack in the existing transducer, which is not subject to voltage, with a metal resonant structure. As a result, this application reduces the amount of piezoelectric ceramic driving crystal stack used by half compared to the existing transducer, thereby avoiding waste of piezoelectric ceramic driving crystal stack and reducing manufacturing costs.

[0055] According to acoustic theory, the first-order longitudinal resonance of a longitudinal vibration transducer occurs when the length of its oscillator is equal to... λ Specifically, when a uniform thin rod with both ends free undergoes longitudinal vibration resonance, its longitudinal vibration displacement can be described by the following equation:

[0056] (3)

[0057] in, ζ Let be the vibrational displacement of one end of the thin rod during longitudinal vibration. c 0 represents the longitudinal wave velocity of the thin rod;

[0058] c 0 can be calculated using the following formula:

[0059] (4)

[0060] in, E Young's modulus of the material used to manufacture thin rods. ρ The density of the material used to manufacture the thin rod;

[0061] Before the longitudinal vibration of a uniform thin rod n The first resonant frequency can be calculated using the following formula:

[0062] (5)

[0063] in, L The length of the rod, ω is the angular frequency.

[0064] According to the formula above, the length of the rod is:

[0065] (6)

[0066] because The wavelength is the first-order longitudinal wave wavelength. When a uniform thin rod undergoes first-order longitudinal vibration resonance, the length of the rod is equal to half the wavelength. The single-ended excitation broadband transducer disclosed in this application includes a piezoelectric ceramic driving crystal stack and a metal resonant structure arranged sequentially along the axial direction of the transducer as its transducer driving element. The length of the piezoelectric ceramic driving crystal stack... The length of the metal resonant structure This results in the length of the slender rod-shaped transducer driven element, composed of a piezoelectric ceramic driving crystal stack and a metal resonant structure, being (or close to) half of its first-order longitudinal vibration wavelength; that is, the length of the slender rod-shaped transducer driven element is equal to or approximately equal to... λ / 2, λ The wavelength of the first-order longitudinal vibration of the transducer drive element.

[0067] The following is a simulation analysis and experimental analysis of the single-ended excitation broadband transducer disclosed in this application:

[0068] This application uses finite element modal analysis to perform modal analysis on the transducer drive element in both existing single-ended broadband transducers and the single-ended broadband transducer disclosed in this application. Finite element modal analysis is a numerical analysis technique based on the finite element method to solve for the inherent vibration characteristics (modal parameters) of a structure. Its core is to discretize the structure, establish dynamic equations, and calculate modal parameters such as the structure's natural frequencies, mode shapes, and damping ratios. We use finite element software to analyze whether the new drive segment achieves its intended purpose.

[0069] First, the first three orders of longitudinal vibration of the transduction drive element (all using piezoelectric ceramic drive stacks) of the existing single-ended excitation broadband transducer are analyzed, and the results are as follows:

[0070] like Figure 9 As shown, the results of modal analysis of the piezoelectric ceramic drive stack are presented. The solid line in the figure represents the drive segment (transducer drive element) without vibration, and the black and white parts represent the deformation trend of the drive segment (transducer drive element). Since the finite element modal analysis results magnify the vibration mode tens of thousands of times to better observe the deformation of the structure, the deformation is somewhat exaggerated. It can be seen from the figure that the first three longitudinal vibration resonant frequencies of the transducer drive element of the existing single-ended excitation broadband transducer are successively the first longitudinal vibration resonant frequencies. =35.8kHz, second-order longitudinal vibration resonant frequency =64.9kHz, third-order longitudinal vibration resonant frequency =79.5kHz.

[0071] like Figure 10 The following is the result of modal analysis of the transducer drive element in this application using finite element software:

[0072] Figure 10As shown in the figure, the solid line represents the drive section (transducer drive element) without vibration, and the black and white parts represent the deformation trend of the drive section (transducer drive element). Since the finite element modal analysis results amplify the vibration mode to better observe the structural deformation, the deformation is somewhat exaggerated. As can be seen from the figure, the first three longitudinal vibration resonant frequencies of the transducer drive element of the single-ended excitation broadband transducer in this application are successively the first longitudinal vibration resonant frequencies. =35.3kHz, second-order longitudinal vibration resonant frequency =66.1kHz, third-order longitudinal vibration resonant frequency =81.4kHz, by Figure 9 and Figure 10 The results show that and , and , and The basic differences are not significant, indicating that the drive section (transducer drive element) of this application has achieved the expected design.

[0073] The drive section (transducer drive element) disclosed in this application was combined with the front and rear cover plates and prestressed screws to form a transducer. The performance of the transducer was simulated, and the simulation results are shown in the figure below.

[0074] Depend on Figure 11 It is known that the transducer's transmit voltage response (TVR) curve has three resonant peaks. The mutual coupling of these three resonant peaks can flatten the TVR curve, resulting in broadband characteristics. This indicates that by connecting the piezoelectric ceramic crystal stack, the perforated metal structure, and the front and rear cover plates together with prestressed bolts, full excitation of the first three longitudinal vibration modes can be achieved, making the transducer's transmit voltage response tend to be flat within the target frequency band.

[0075] Furthermore, the metal resonant structure is a metal rod-shaped structure.

[0076] Specifically, such as Figure 6 and Figure 7 As shown, the metal resonant structure is a metal rod-shaped structure with a central through hole. The metal resonant structure adopts a metal rod-shaped structure, which has the advantages of simple structure and convenient manufacturing.

[0077] Furthermore, the metal rod-shaped structure is also provided with weight-reducing holes 210 arranged in the axial direction.

[0078] Specifically, such as Figure 6 , Figure 7 and Figure 8As shown, the metal rod-shaped structure is also provided with weight reduction holes 210 arranged along the axial direction. By setting weight reduction holes 210, the equivalent density of the metal rod-shaped structure (metal resonant structure) can be reduced, thereby reducing the equivalent longitudinal wave velocity of the structure. This can effectively reduce the length of the metal rod-shaped structure (metal resonant structure) in the longitudinal vibration direction, thereby reducing the volume of the single-end excited broadband transducer and better realizing the small-size acoustic emission of the transducer.

[0079] Furthermore, the weight-reducing holes are elongated holes that extend along the axial direction of the metal rod-shaped structure and have a circular cross-section, and the plurality of weight-reducing holes are evenly distributed in a ring on the cross-section of the metal rod-shaped structure.

[0080] Specifically, in this embodiment, such as Figure 12 and Figure 13 As shown, preferably, multiple elongated holes with circular cross-sections are evenly distributed in a ring along the axial direction of the metal rod structure. The elongated holes penetrate both ends of the metal rod structure. By evenly distributing multiple circular elongated holes on the metal rod structure, the equivalent density of the metal rod structure (metal resonant structure) can be reduced, thereby reducing the equivalent longitudinal wave velocity of the structure. This effectively reduces the length of the metal rod structure (metal resonant structure) in the longitudinal vibration direction, thus reducing the volume of the single-end excited broadband transducer and better realizing the small-size acoustic emission of the transducer. At the same time, it can also avoid the bending of the cavity sidewall of the perforated structure caused by opening holes in the metal rod structure, which would affect the longitudinal vibration performance of the sound waves. That is, periodic openings can better control the structural quality, reduce the equivalent density of the perforated metal structure, and thus reduce the equivalent longitudinal wave velocity of the structure, thereby reducing the longitudinal length of the metal rod structure in this application.

[0081] Furthermore, the metal rod-shaped structure is made of duralumin.

[0082] Specifically, the metal rod structure (metal resonant structure) is made of hard aluminum, which not only gives it good mechanical properties and high strength, but also makes it easy to process. In addition, it has low density and low longitudinal wave velocity, which can further reduce the length of the metal rod structure (metal resonant structure) in the longitudinal vibration direction, thereby reducing the volume of the single-end excited broadband transducer and better realizing the small-size acoustic emission of the transducer.

[0083] Furthermore, the front cover is made of hard aluminum, and the rear cover is made of brass.

[0084] Specifically, the front cover is made of duralumin, and the rear cover is made of brass. The front cover extends forward, and the rear cover extends backward. According to the law of conservation of momentum, the duralumin front cover, with its smaller mass, has a higher vibration velocity, while the brass rear cover, with its larger mass, has a lower vibration velocity. Since only the front cover of the transducer is in contact with the water and radiates sound energy into it, using a lightweight front cover increases its vibration velocity, thereby radiating more sound energy into the water.

[0085] Furthermore, it also includes a metal sleeve, in which the transducer drive element, the rear cover plate, and the prestressed screw are placed. The metal sleeve is provided with a vibration isolation structure, and the other end of the metal sleeve is watertightly fixedly connected to the front cover plate.

[0086] Specifically, it also includes a metal sleeve, one end of which is closed and the other end is open. The rear cover plate, the piezoelectric ceramic driving crystal stack 20, and the metal resonant structure 21 can extend into the metal sleeve through the open end. The open end of the metal sleeve is watertightly fixed to one side of the front cover plate. Vibration isolation material is also provided inside the metal sleeve. The metal sleeve can effectively achieve sealing protection and vibration protection for the piezoelectric ceramic driving crystal stack 20 and the metal resonant structure 21.

[0087] The specific design process of the single-ended excitation broadband transducer disclosed in this application can be as follows: Select (fabricate) a corresponding piezoelectric ceramic crystal stack according to the design parameter requirements of the transducer; first analyze the first-order longitudinal vibration of the piezoelectric ceramic crystal stack using finite element software to obtain its resonant frequency. Then, an open-hole metal structure (metal resonant structure) was designed, and the cross-section of the open-hole metal structure and the cross-section of the piezoelectric ceramic stack were matched. The dimensions of the internal annular cavity (weight reduction hole) of the open-hole metal structure were modified, and finite element simulation analysis was used to adjust the parameters so that the first-order longitudinal vibration resonant frequency of the open-hole metal structure was consistent with the first-order longitudinal vibration resonant frequency of the piezoelectric crystal stack. Thus, the resonant frequency of the open-hole metal structure in the resonant structure was calculated. wavelength at frequency λ 3. Use λ Replacement of 3 / 4 length perforated metal structure λ A quarter-length un-energized upper half of a piezoelectric ceramic section. λ 1 / 4 length of electrically charged lower half-section piezoelectric ceramic and λ The upper half of the perforated metal structure, which is 3 / 4 of the length, is glued together to form a new drive section (transducer drive element). By bolting the piezoelectric ceramic crystal stack, the perforated metal structure, and the front and rear cover plates together with prestressed screws, full excitation of the first three longitudinal vibration modes can be achieved, making the transducer's emission voltage response tend to be flat within the target frequency band.

[0088] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A single-ended excitation broadband transducer, comprising a front cover plate, a transducing driving element, a rear cover plate and a pre-stressed screw rod, the front cover plate, the transducing driving element and the rear cover plate are sequentially arranged, the rear cover plate and the transducing driving element are sequentially penetrated by the pre-stressed screw rod and fixedly connected with the front cover plate, characterized in that: The transducer drive element includes a piezoelectric ceramic drive crystal stack and a metal resonant structure arranged sequentially along the axial direction of the transducer. One end of the piezoelectric ceramic drive crystal stack and one end of the metal resonant structure are bonded together, and the other end is connected to one side of the rear cover plate. ​ The length of the piezoceramic drive stack As follows: （1） wherein represents a longitudinal wave speed of the piezoelectric ceramic drive stack, represents a first order longitudinal vibration resonance frequency of the piezoelectric ceramic drive stack; The cross-section of the metal resonant structure is consistent with the cross-section of the piezoelectric ceramic driving crystal stack, and the length of the metal resonant structure is... as follows: （2） in, The longitudinal wave velocity of a metallic resonant structure. This represents the first-order longitudinal resonant frequency of a metallic resonant structure. and Consistent.

2. The single-ended excitation broadband transducer according to claim 1, characterized in that: The metal resonant structure is a metal rod-shaped structure.

3. The single-ended excitation broadband transducer according to claim 2, characterized in that: The metal rod-shaped structure also has multiple weight-reducing holes arranged along the axial direction.

4. The single-ended excitation broadband transducer according to claim 3, characterized in that: The weight-reducing holes are elongated holes that extend along the axial direction of the metal rod-shaped structure and have a circular cross-section. The plurality of weight-reducing holes are evenly distributed in a ring on the cross-section of the metal rod-shaped structure.

5. The single-ended excitation broadband transducer according to claim 4, characterized in that: The metal rod-shaped structure is made of duralumin.

6. The single-ended excitation broadband transducer according to claim 1, characterized in that: The piezoelectric ceramic driven crystal stack includes an even number of piezoelectric ceramic ring plates and an odd number of metal ring plates. The piezoelectric ceramic ring plates and the metal ring plates are bonded together alternately. The polarization directions of adjacent piezoelectric ceramic ring plates are opposite. Wires are welded onto the metal ring plates.

7. The single-ended excitation broadband transducer according to claim 1, characterized in that: The front cover is made of hard aluminum and has a horn-shaped structure that gradually increases in size from one end in contact with the metal resonant structure to the other end; the rear cover is made of brass.

8. The single-ended excitation broadband transducer according to claim 1, characterized in that: It also includes a metal sleeve, in which the transducer drive element, the rear cover plate and the prestressed screw are placed. The metal sleeve is provided with a vibration isolation structure, and the other end of the metal sleeve is watertightly fixed to the front cover plate.

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