A high-efficiency electro-electric transducer with circumferential radiation multi-electrode oscillator

Abstract

This invention proposes a high-efficiency electro-electric transducer with circumferential radiation and multiple vibrators, belonging to the field of underwater acoustic transducers. It solves the problems of large space occupation and complex installation associated with existing technologies that use multiple electro-electric transducers. It includes a housing, multiple driving vibrators, and a pressure-balancing airbag. The housing includes a central ring and multiple vibrator cover plates. The central ring has multiple receiving holes spaced apart along its circumference. Each vibrator cover plate is located at one end of a receiving hole. The multiple driving vibrators are electrically connected and loaded with a current of the same amplitude and phase, generating radial acoustic radiation. The pressure-balancing airbag is located on the inner wall of the central hole of the central ring. The gas inside the pressure-balancing airbag is connected to the gas inside each of the multiple driving vibrators. The vibrator cover plates and the pressure-balancing airbag are located at opposite ends of the driving vibrators. It improves radiated acoustic power and electro-acoustic efficiency, is easy to install, and does not occupy the internal space of the underwater unmanned vehicle.

Description

Technical Field

[0001] This invention belongs to the field of underwater acoustic transducer technology, and in particular relates to a high-efficiency electric transducer with a multi-element oscillator that radiates in a circular pattern. Background Technology

[0002] Sound waves are the only energy carrier that can travel long distances in seawater. Acoustic methods are the main means for humans to explore and develop the ocean. Transducers are key equipment in underwater acoustics research. Based on their different working states, transducers are divided into two main categories: one is the transmitting transducer, which converts electrical signals into mechanical energy and drives the radiating medium to vibrate, thereby converting the electrical signals into sound signals and transmitting information outward; the other is the receiving transducer, which receives external sound signals and converts them into electrical signals, and after amplification and processing, identifies the information in the sound signals.

[0003] Transducers include piezoelectric transducers, electrodynamic transducers, and rare-earth transducers. There is a theoretical contradiction between small size, low frequency, and high-power sound generation in piezoelectric transducers. For example, to maintain high emission efficiency and radiated acoustic power during operation, the transducer typically operates in a resonant state. However, the resonant frequency of a typical piezoelectric transducer is inversely proportional to the size of its functional material; that is, a lower resonant frequency means a larger and heavier transducer. Furthermore, since radiated acoustic power is positively correlated with radiation resistance and the radiating surface velocity, and radiation resistance is positively correlated with the radiating surface area and vibration frequency, reducing the operating frequency and decreasing the radiating surface size will significantly reduce radiated acoustic power while keeping the radiating surface velocity constant. Therefore, to maintain or increase the radiated acoustic power while reducing the transducer size and operating frequency, the radiating surface velocity must be significantly increased to obtain sufficient volume velocity. However, due to limitations in the power of the drive module and the mechanical strength of the transducer itself, achieving low-frequency, small-size, high-power transmission by significantly increasing the radiating surface vibration velocity is often difficult.

[0004] Electrodynamic transducers are a commonly used type of ultra-low frequency (UHF) transducer in underwater acoustics, and their working mechanism is similar to that of moving-coil loudspeakers commonly used in air. Unlike common piezoelectric and rare-earth transducers, the operating frequency of an electrodynamic transducer does not depend on its structural size, but rather on the stiffness of the suspension spring and the mass of the moving parts. Therefore, by using a more flexible suspension spring, the resonant frequency of the transducer can be set to tens of hertz or even hundreds of hertz, thus extending the lower limit of the operating frequency of the electrodynamic transducer to several hertz. Thus, electrodynamic transducers are characterized by small size, ultra-low frequency, and ultra-wideband emission. The mechanical vibration model of an electrodynamic transducer can be considered as a single-degree-of-freedom mass-spring-damped mechanical vibration system, and the sound radiation model can be considered as single-sided piston sound radiation under low-frequency conditions. Therefore, the electrodynamic transducer has a flat source-level response over a fairly wide frequency band above the resonant frequency. These performance characteristics make electrodynamic transducers frequently used in ship radiated noise simulators, acoustic decoys and other underwater acoustic countermeasures equipment, as well as sonar calibration systems and pipeline silencing experiments.

[0005] However, in existing technologies, the extremely low radiation resistance of electrodynamic transducers in the low-frequency range results in low electroacoustic efficiency of a single transducer, typically less than 1%. While it is possible to improve low-frequency radiation resistance and thus radiated acoustic power and electroacoustic efficiency by rationally utilizing the mutual radiation effect of multiple electrodynamic transducers in close proximity, this requires significant space and is complex to install. Summary of the Invention

[0006] In view of this, in order to solve the problem that the existing technology improves the low-frequency radiation resistance by making reasonable use of the mutual radiation effect of multiple electric transducers in close proximity, but setting multiple electric transducers in close proximity not only occupies a lot of space but also makes the installation complicated, this invention proposes a circular radiation multi-electrode high-efficiency electric transducer.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A high-efficiency electrodynamic transducer with circular radiation and multiple oscillators includes:

[0009] The housing includes a central ring and multiple oscillator cover plates. The central ring is provided with multiple receiving holes spaced apart along its circumference. The multiple receiving holes and the multiple oscillator cover plates correspond one-to-one. The oscillator cover plates cover one end of the receiving holes.

[0010] Multiple driving oscillators are located one-to-one in multiple receiving holes, and the multiple driving oscillators are electrically connected to each other. Currents of the same amplitude and phase are applied to the multiple driving oscillators to generate radial sound radiation.

[0011] The pressure balancing airbag has a central hole in the central ring body. The pressure balancing airbag is disposed on the inner wall of the central hole, and the gas inside the pressure balancing airbag is in communication with the gas inside multiple driving oscillators. The oscillator cover plate and the pressure balancing airbag are respectively located at both ends of the driving oscillator.

[0012] As a preferred embodiment of the aforementioned circular radiation multi-electrode high-efficiency electric transducer, the driving transducer includes a radiating surface, a positioning rod, a spring, an upper magnetic circuit, a permanent magnet ring, a coil, an outer magnetic circuit, an exciter base, and a central filler. The outer magnetic circuit is fixedly disposed on the exciter base, and the central filler is fixedly connected to the exciter base. The upper magnetic circuit and the permanent magnet ring are both located between the outer magnetic circuit and the central filler. The coil is located between the upper magnetic circuit and the outer magnetic circuit. One end of the positioning rod is fixedly connected to the radiating surface, and the other end is slidably connected to the exciter base. The spring is sleeved on the positioning rod.

[0013] As a preferred embodiment of the aforementioned circular radiation multi-electrode high-efficiency electric transducer, the positioning rod is connected to the exciter base via a linear bearing.

[0014] As a preferred embodiment of the aforementioned circumferential radiation multi-electrode high-efficiency electric transducer, the transducer cover plate is provided with multiple first through holes.

[0015] As a preferred embodiment of the aforementioned circumferential radiation multi-electrode high-efficiency electric transducer, a rubber membrane is provided between the driving transducer and the transducer cover plate.

[0016] As a preferred embodiment of the aforementioned circumferential radiating multi-electrode high-efficiency electro-electric transducer, the circumferential radiating multi-electrode high-efficiency electro-electric transducer further includes two side cover plates, both of which are fixedly connected to the central ring body, and the two side cover plates are respectively placed on both ends of the central hole.

[0017] As a preferred embodiment of the aforementioned circumferential radiation multi-electrode high-efficiency electric transducer, the side cover plate is provided with multiple second through holes.

[0018] As a preferred embodiment of the aforementioned circular radiation multi-electrode high-efficiency electric transducer, the central ring is fixedly provided with a handle.

[0019] As a preferred embodiment of the aforementioned circumferential radiation multi-electrode high-efficiency electric transducer, the pressure balancing airbag is a thin-walled rubber bladder.

[0020] As a preferred embodiment of the aforementioned circumferential radiation multi-electrode high-efficiency electric transducer, the side of the central ring is provided with a circular hole, which enables the drive transducer to be connected to the transmission cable.

[0021] Compared with the prior art, the beneficial effects of the circular radiation multi-electrode high-efficiency electrodynamic transducer provided by the present invention are:

[0022] 1. This invention provides a circumferentially radiating multi-electrode high-efficiency electrodynamic transducer. The transducer has a central ring as its frame, with a large central hole for housing a pressure balancing airbag. Multiple smaller receiving holes are arranged circumferentially to house the driving oscillators and connect the driving oscillators to the gas environment of the pressure balancing airbag. The pressure balancing airbag maintains pressure balance between the area outside the radiation surface of each driving oscillator and the area inside the central hole, thus maintaining pressure balance above and below the driving oscillators and ensuring the radiation surface operates in a balanced position. The size of the pressure balancing airbag determines the maximum operating depth of the electrodynamic transducer. Multiple driving oscillators are embedded circumferentially within the central ring and share the pressure balancing airbag.

[0023] 2. This invention provides a circularly radiating multi-electrode high-efficiency electrodynamic transducer, wherein the number of driving oscillators is N, where N≥2. When operating in the low-frequency range, the spacing between the driving oscillators is much smaller than the wavelength, resulting in strong mutual radiation and a large mutual radiation impedance. The radiation impedance of each driving oscillator is N times that of individual radiators, and both the radiated acoustic power and electroacoustic efficiency become N times that of individual radiators at the same vibration velocity. The low-frequency radiated acoustic power of the entire circularly radiating multi-electrode high-efficiency electrodynamic transducer is N times that of individual driving oscillators. 2 The transducer's sound source level can be improved by 20lgN.

[0024] This circularly radiating multi-electrode high-efficiency electrodynamic transducer utilizes the small size and low-frequency acoustic emission characteristics of electrodynamic transducers. Furthermore, by leveraging the strong mutual radiation between multiple driving elements, it significantly improves the radiation resistance of the driving elements in the low-frequency range, thereby substantially enhancing the radiated acoustic power and electroacoustic efficiency of the electrodynamic transducer in the low-frequency range.

[0025] 3. This invention provides a circularly radiating multi-electrode high-efficiency electric transducer. This circularly radiating multi-electrode high-efficiency electric transducer can be used as a section of an underwater vehicle. It can be conformally installed between two sections of an unmanned underwater vehicle (UUV) without increasing the drag of the underwater vehicle. It also makes reasonable use of the internal volume of the underwater UUV, is easy to install, and does not occupy the internal space of the underwater UUV.

[0026] This circularly radiating multi-electrode high-efficiency electric transducer can be applied to underwater ship radiated noise simulators, acoustic decoys, noise interference and other underwater acoustic countermeasures equipment, as well as sonar calibration systems, pipeline noise reduction experiments and other fields. Attached Figure Description

[0027] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0028] Figure 1 This is a cross-sectional view of a circularly radiating multi-electrode high-efficiency electrodynamic transducer provided in a specific embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of the structure of the driving oscillator of the circularly radiating multi-element oscillator high-efficiency electric transducer provided in a specific embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram of the structure of a high-efficiency electric transducer with circumferential radiation of multiple oscillators provided in a specific embodiment of the present invention;

[0031] Figure 4 This is a schematic diagram of the installation position of a circularly radiating multi-electrode high-efficiency electrodynamic transducer provided in a specific embodiment of the present invention.

[0032] In the picture:

[0033] 1. Drive oscillator; 2. Central ring; 3. Pressure balance airbag; 4. Radial surface; 5. Positioning rod; 6. Upper magnetic circuit; 7. Permanent magnet ring; 8. Oscillator cover plate; 9. Coil; 10. External magnetic circuit; 11. Exciter base; 12. Central filler; 13. Spring; 14. Circular hole; 15. Handle; 16. Side cover plate;

[0034] 100. Substructure of an underwater vehicle. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other, and the described embodiments are only some embodiments of the present invention, not all embodiments.

[0036] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0037] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0038] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0039] See Figure 1-4 This invention provides a circularly radiating multi-electrode high-efficiency electric transducer, comprising a housing, multiple driving transducers 1, and a pressure balancing airbag 3. The housing includes a central ring 2 and multiple transducer cover plates 8. The central ring 2 has multiple receiving holes spaced apart along its circumference, with each receiving hole corresponding to one of the multiple transducer cover plates 8. The transducer cover plates 8 cover one end of each receiving hole. The multiple driving transducers 1 are located within the multiple receiving holes, and are electrically connected to each other. A current of the same amplitude and phase is applied to each of the multiple driving transducers 1 to generate radial sound radiation. The central ring 2 has a central hole, and the pressure balancing airbag 3 is disposed on the inner wall of the central hole. The gas inside the pressure balancing airbag 3 is in communication with the gas inside each of the multiple driving transducers 1. The transducer cover plates 8 and the pressure balancing airbag 3 are located at opposite ends of the driving transducers 1.

[0040] This circumferentially radiating, multi-electrode, high-efficiency electrodynamic transducer has a central ring 2 as its frame. The central ring 2 has a large central hole for housing a pressure balancing airbag 3, and multiple smaller accommodating holes along the circumference for housing the drive transducers 1 and connecting the drive transducers 1 to the gas environment of the pressure balancing airbag 3. The pressure balancing airbag 3 maintains pressure balance between the radiation surface 4 of each drive transducer 1 and the central hole, thus maintaining pressure balance above and below the drive transducers 1 and ensuring that the radiation surface 4 operates in a balanced position. The size of the pressure balancing airbag 3 determines the maximum working depth of the electrodynamic transducer. Multiple drive transducers 1 are embedded circumferentially within the central ring 2 and share the pressure balancing airbag 3. When multiple drive transducers 1 are arranged close together, according to the principle of mutual radiation in the sound field, the radiated sound power of each drive transducer 1 is many times that of individual sound radiation, and the electroacoustic efficiency of each drive transducer 1 is also many times that of individual radiation. Therefore, the electro-electric transducer composed of multiple driving oscillators 1 has the characteristic of high-efficiency emission, which improves the radiated acoustic power and electro-acoustic efficiency of the electro-electric transducer.

[0041] This circularly radiating multi-electrode high-efficiency electrodynamic transducer, such as Figure 4 As shown, it can be used as a section of an underwater vehicle, and can be conformally installed between two sections of an unmanned underwater vehicle (UUV). It does not increase the drag of the underwater vehicle, and makes reasonable use of the internal volume of the underwater UUV. It is easy to install and does not occupy the internal space of the underwater UUV.

[0042] This circularly radiating multi-electrode high-efficiency electric transducer can be applied to underwater ship radiated noise simulators, acoustic decoys, noise interference and other underwater acoustic countermeasures equipment, as well as sonar calibration systems, pipeline noise reduction experiments and other fields.

[0043] In this embodiment, the number of driving oscillators 1 is N, where N≥2. When this circularly radiating multi-electrode high-efficiency electrodynamic transducer operates in the low-frequency range, the spacing between the driving oscillators 1 is much smaller than the wavelength, resulting in strong mutual radiation and a large mutual radiation resistance. The radiation resistance of each driving oscillator 1 is N times that of individual radiation, and both the radiated acoustic power and electroacoustic efficiency become N times that of individual radiation at the same vibration velocity. The low-frequency radiated acoustic power of the entire circularly radiating multi-electrode high-efficiency electrodynamic transducer is N times that of individual radiation by a single driving oscillator 1. 2 The transducer's sound source level can be improved by 20lgN.

[0044] This circularly radiating multi-electrode high-efficiency electrodynamic transducer utilizes the small size and low-frequency acoustic emission characteristics of electrodynamic transducers. Furthermore, by leveraging the strong mutual radiation between multiple driving oscillators 1, the radiation resistance of the driving oscillators 1 in the low-frequency band is significantly improved, thereby substantially enhancing the radiated acoustic power and electroacoustic efficiency of the electrodynamic transducer in the low-frequency band.

[0045] It is understandable that the electrical connection between multiple driving oscillators 1 can be a series connection, a parallel connection, or a series connection followed by a parallel connection.

[0046] In this embodiment, the receiving hole is T-shaped, and the driving oscillator 1 is also T-shaped. After the driving oscillator 1 is inserted into the T-shaped receiving hole, the oscillator cover plate 8 is covered, and bolts are used to fix each driving oscillator 1 to the central ring 2. While ensuring the watertightness of the driving oscillator 1, the pressure balancing airbag 3 is allowed to fully contact the water environment.

[0047] Optionally, such as Figure 2 As shown, the driving oscillator 1 includes a radiating surface 4, a positioning rod 5, a spring 13, an upper magnetic circuit 6, a permanent magnet ring 7, a coil 9, an outer magnetic circuit 10, an exciter base 11, and a central filler 12. The outer magnetic circuit 10 is fixedly mounted on the exciter base 11, and the central filler is fixedly connected to the exciter base 11. The upper magnetic circuit 6 and the permanent magnet ring 7 are both located between the outer magnetic circuit 10 and the central filler. The coil 9 is located between the upper magnetic circuit 6 and the outer magnetic circuit 10. One end of the positioning rod 5 is fixedly connected to the radiating surface 4, and the other end is slidably connected to the exciter base 11. The spring 13 is sleeved on the positioning rod 5. The radiating surface 4 achieves axial reciprocating vibration using the positioning rod 5, and the radiating surface 4 is connected to the exciter base 11 by the spring 13, which provides restoring force.

[0048] Optionally, a rubber diaphragm is provided between the drive oscillator 1 and the oscillator cover plate 8. The rubber diaphragm is vulcanized at the edge of the radiating surface 4, and the outer edge of the rubber diaphragm is pressed tightly by the oscillator cover plate 8 and the outer magnetic circuit 10, which serves to ensure the watertightness and airtightness of the transducer. While ensuring the watertightness of the drive oscillator 1, it ensures that the pressure balancing airbag 3 and the rubber diaphragm wrapped on the radiating surface 4 of each drive oscillator 1 are in full contact with the water environment.

[0049] Optionally, the positioning rod 5 is connected to the vibrator base 11 via a linear bearing.

[0050] Optionally, the vibrator cover plate 8 is provided with multiple first through holes. The vibrator cover plate 8 has densely packed circular first through holes in its center, which serve to allow sound transmission. The vibrator cover plate 8 protects the radiating surface 4 and the rubber membrane while ensuring full contact between the rubber membrane and the external water environment. The outer periphery of the vibrator cover plate 8 is connected to the central ring 2 by bolts.

[0051] Optionally, the circumferentially radiating multi-electrode high-efficiency electric transducer also includes two side cover plates 16, both of which are fixedly connected to the central ring 2. The two side cover plates 16 are respectively installed at both ends of the central hole. The side cover plates 16 are connected to the central ring 2 by bolts, and the pressure balancing airbag 3 is located between the two side cover plates 16, which serve to protect the pressure balancing airbag 3.

[0052] Optionally, the side cover plate 16 is provided with multiple second through holes. The side cover plate 16 also has densely packed circular second through holes in the center, so that the side cover plate 16 can protect the pressure balancing airbag 3 while allowing the pressure balancing airbag 3 to fully contact the external water environment.

[0053] Optionally, the central ring 2 is fixedly provided with a handle 15. It is understood that a base is welded to the side of the central ring 2, and the handle 15 is welded to the base. In this embodiment, the central ring 2 is provided with two sets of handles 15.

[0054] Optionally, a circular hole 14 pointing to the center is provided on the side of the central ring 2 to install a pluggable underwater connector, so as to connect each drive oscillator 1 to the transmission cable.

[0055] Optionally, the pressure balancing airbag 3 is a thin-walled rubber bladder. After vulcanization, the pressure balancing airbag 3 is attached to the inner wall of the central hole of the central ring body 2.

[0056] Optionally, the central ring 2 is made of a corrosion-resistant metal material. The central ring 2 can be made of corrosion-resistant metals such as stainless steel or titanium alloy.

[0057] Optionally, the vibrator cover plate 8 is made of a corrosion-resistant metal such as titanium alloy, and the side cover plate 16 is made of a corrosion-resistant metal such as titanium alloy.

[0058] Obviously, the above-disclosed embodiments of the present invention are merely illustrative of the invention. The embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. It is neither necessary nor possible to exhaustively list all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A circumferentially radiated multi-element transducer of the electrodynamic type, characterized in that, The utility model relates to a kind of multi-axial vibration exciter, including: Shell, including center ring (2) and multiple vibrator cover plate (8), center ring (2) is spaced apart with multiple accommodating holes along its circumferential direction, multiple accommodating holes and multiple vibrator cover plate (8) one-to-one, and the vibrator cover plate (8) is covered at one end of the accommodating hole; Multiple drive vibrator (1), multiple drive vibrator (1) is one-to-one in multiple accommodating holes, and multiple drive vibrator (1) is electrically connected, and multiple drive vibrator (1) is loaded with same amplitude and same phase current, to generate radial acoustic radiation; Pressure balance air bag (3), the center ring (2) has center hole, and the pressure balance air bag (3) is arranged on the inner wall of the center hole, and the gas in the pressure balance air bag (3) is communicated with the gas in multiple drive vibrator (1), and the vibrator cover plate (8) and the pressure balance air bag (3) are located at both ends of the drive vibrator (1) respectively;The drive vibrator (1) includes radiation surface (4), positioning rod (5), spring (13), upper magnetic circuit (6), permanent magnet magnetic ring (7), coil (9), outer magnetic circuit (10), exciter base (11) and center filler (12), the outer magnetic circuit (10) is fixedly arranged on the exciter base (11), the center filler is fixedly connected with the exciter base (11), and the upper magnetic circuit (6) and the permanent magnet magnetic ring (7) are located between the outer magnetic circuit (10) and the center filler, the coil (9) is located between the upper magnetic circuit (6) and the outer magnetic circuit (10), one end of the positioning rod (5) is fixedly connected with the radiation surface (4), the other end is slidably connected with the exciter base (11), and the spring (13) is sleeved on the positioning rod (5).

2. The circumferentially radiating multi-element transducer of claim 1, wherein: The positioning rod (5) is connected with the exciter base (11) by linear bearing.

3. The circumferentially radiating, multi-element, pancake transducer of claim 1, wherein: The side of the center ring (2) is provided with a circular hole (14), and the circular hole (14) can realize the connection of the drive vibrator (1) and the transmission cable.

4. The circumferentially radiating, multi-element, pancake transducer of claim 1, wherein: Rubber film is arranged between the drive vibrator (1) and the vibrator cover plate (8).

5. The circumferentially radiated multi-element transducer of claim 1, wherein: The vibrator cover plate (8) is provided with a plurality of first through holes.

6. The circumferentially radiated multi-element transducer of claim 1, wherein: Two side cover plates (16) are further included, both of which are fixedly connected with the center ring (2), and both of which are covered at both ends of the center hole.

7. The circumferentially radiated multi-element transducer of claim 6, wherein: The side cover plate (16) is provided with a plurality of second through holes.

8. The circumferentially radiated multi-element transducer of claim 1, wherein: The center ring (2) is fixedly provided with a handle (15).

9. The circumferentially radiated multi-element transducer of claim 1, wherein: The pressure balance air bag (3) is a thin-walled rubber bag.

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