A supercharged low-frequency pressure hydrophone

Abstract

The application discloses a kind of supercharged low-frequency pressure hydrophone, and the hydrophone includes: front shell, back cover, supercharged component and sensitive element, supercharged component is connected with sensitive element and is contained in the inside of front shell, and the cooperation realizes the monitoring of underwater sound pressure fluctuation;Back cover is assembled in front shell by threaded connection;Supercharged component is equipped with the first pressure surface, second pressure surface and third pressure surface with conical surface;Third pressure surface is connected with second pressure surface by first connecting shaft, and second pressure surface is connected with first pressure surface by second connecting shaft, and pressure surface is used to receive the pressure of pipeline sound radiation wave;First pressure surface, second pressure surface and third pressure surface all have conical surface;Connecting mode is selected from bonding or welding;The outer diameter of three pressure surfaces is same, and the taper angle of conical surface is consistent.The application is arranged array type pressure surface in the extension direction of hydrophone, and the effective pressure area of disc type hydrophone is increased, so as to break through size constraint and improve sensitivity.

Description

Technical Field

[0001] This invention relates to the field of underwater acoustic transducer technology, and more particularly to a pressurized low-frequency pressure hydrophone. Background Technology

[0002] A hydrophone is an acoustic transducer that receives acoustic signals in water and converts them into electrical signals. It is widely used in underwater detection, pipeline communication, leak location, and other applications. Because underwater acoustic signals are typically weak, the sensing element of a hydrophone is often made of piezoelectric ceramic material, and to optimize energy conversion efficiency, types with higher piezoelectric constants are preferred. Among these, disc-shaped piezoelectric ceramics are widely used sensing elements; their operating mode is thickness vibration mode, and the end face is often used as the sound pressure input.

[0003] However, in some practical applications, the installation dimensions of the hydrophone are fixed in advance (for example, the mounting hole is an E3 / 4 threaded hole), which makes it impossible to freely adjust the outer diameter of the corresponding sensitive element.

[0004] In particular, for the disc-type piezoelectric ceramics with the aforementioned thickness vibration mode, the effective pressure-bearing area is limited by the fixed outer diameter, which severely restricts the conventional technical approach of "increasing sensitivity by increasing the size of the sensitive element" and directly limits the potential for improving the sensitivity of the hydrophone. Summary of the Invention

[0005] This invention provides a pressure-boosting low-frequency pressure hydrophone. By arranging an array of pressure surfaces along the extended direction of the hydrophone, the effective pressure-bearing area of ​​the disc-shaped hydrophone is increased, thereby overcoming size constraints and improving sensitivity. See the description below for details:

[0006] A pressurized low-frequency pressure hydrophone includes: a front housing, a rear cover, a pressurizing component, and a sensitive element.

[0007] The pressurization component is connected to the sensitive element and is housed together inside the front shell. The two work together to monitor underwater sound pressure fluctuations. The rear cover is assembled to the front shell by a threaded connection.

[0008] The pressurizing component is provided with a first pressure surface, a second pressure surface and a third pressure surface, each having a conical surface; the third pressure surface is connected to the second pressure surface through a first connecting shaft, and the second pressure surface is connected to the first pressure surface through a second connecting shaft; the pressure surfaces are used to receive the pressure of the acoustic radiation waves from the pipeline.

[0009] The first pressure surface, the second pressure surface, and the third pressure surface all have conical surfaces; the connection method is selected from bonding or welding; the outer diameters of the three pressure surfaces are the same, and the cone angles of the conical surfaces are consistent.

[0010] One end of the first pressure surface is bonded and fixed to one side of the sensitive element by an elastic adhesive layer; a sealing groove is provided on the side of the first pressure surface for installing the first sealing ring; the bottom end faces of the second and third pressure surfaces are both provided with adhesive isolation pads.

[0011] An insulating pad and a shielding substrate are sequentially assembled on the other side of the sensitive element. The other end of the shielding substrate is supported against the inner wall of the rear cover, and the two form an axial positioning fit.

[0012] The shielding substrate has a first chamber inside for accommodating the circuit board, and the outer side of the shielding substrate has a through hole and a wiring groove at the position corresponding to the bonding wire notch.

[0013] The signal lines soldered to the sensitive components pass through the solder wire notch, the wiring groove, and the wire hole in sequence, and are connected to the circuit board in the first chamber.

[0014] The front housing is provided with multiple signal windows and two isolation plates;

[0015] The opening positions of each signal window correspond to the sides of the first pressure surface and the second pressure surface, so that the sides of the first pressure surface and the second pressure surface are in direct contact with the fluid.

[0016] The two isolation plates are designed to be separate and are used to support and bond the isolation pads. The isolation pads prevent the bottom surfaces of the second and third pressure surfaces from coming into contact with water.

[0017] Furthermore, the front housing is also provided with a circular sealing surface and a second chamber, and the size of the second chamber is slightly larger than the size of the circular sealing surface; the first sealing ring on the pressurizing component is adapted to contact the circular sealing surface to achieve sealing of the front end of the hydrophone; the edge of the pressurizing component is provided with a protruding edge, which engages and is positioned with the end face of the second chamber during assembly.

[0018] The thickness of the elastic adhesive layer and the quality of the pressure surface must meet the following requirements:

[0019] in, Operating frequency;

[0020] The force enhancement factor R of piezoelectric ceramics is given by the following formula: .

[0021] The beneficial effects of the technical solution provided by this invention are:

[0022] 1. When the outer diameter of the hydrophone is constrained by a fixed thread (such as E3 / 4) and the size of the sensitive element cannot be increased, an array of pressure surfaces (e.g., three conical pressure surfaces) is set in the axial extension direction, which effectively increases the sound pressure receiving area, thereby significantly improving the output signal strength and overall sensitivity of the hydrophone.

[0023] 2. The use of a mass block structure combined with a rigid elastic adhesive layer forms a "mass-spring" resonant system, which enables the hydrophone to have high sensitivity and wide dynamic range in the low frequency range of 10 Hz–5kHz (especially 100–500 Hz), and can effectively capture the characteristic sound signals generated by minute leaks in water supply or oil and gas pipelines.

[0024] 3. The pressure surface adopts a 90° conical design, and together with the side signal window on the front shell, the hydrophone can efficiently capture the sound radiation waves incident from the side, improving the response consistency and detection reliability in multi-directional sound field environments.

[0025] 4. Low-density, high-strength PEEK (polyether ether ketone) material is selected to make the pressure surface, reducing the total mass of the system to maintain a higher natural frequency; at the same time, high-elastic modulus polyurethane adhesive is used as the elastic bonding layer, which allows for a thicker adhesive layer while meeting the mechanical transmission efficiency, reducing the difficulty of the manufacturing process and improving product consistency and long-term stability. Attached Figure Description

[0026] Figure 1 A schematic diagram of the external structure of a pressurized low-frequency pressure hydrophone;

[0027] Figure 2 This is a schematic diagram of the booster component;

[0028] Figure 3 This is a cross-sectional view of a pressurized low-frequency pressure hydrophone;

[0029] Figure 4 This is a schematic diagram of the internal structural connections of a pressurized low-frequency pressure hydrophone.

[0030] Figure 5 This is a schematic diagram of the front shell.

[0031] The attached diagram lists the components represented by each number as follows:

[0032] 1: Front cover; 2: Back cover;

[0033] 3: Pressure boosting components; 4: Sensitive elements;

[0034] 5: First sealing ring; 6: Insulating gasket;

[0035] 7: Shielding substrate; 8: Second sealing ring;

[0036] 9: Locking nut; 10: External cable;

[0037] The front shell 1 includes:

[0038] 101: Signal window; 102: Isolation plate;

[0039] 103: Circular sealing surface; 104: Second chamber;

[0040] 105: Welding surface; 106: External thread;

[0041] The booster component 3 includes:

[0042] 301: First pressure surface; 302: Second pressure surface;

[0043] 303: Third pressure surface; 304: First connecting shaft;

[0044] 305: Second connecting shaft; 306: Elastic adhesive layer;

[0045] 307: Sealing groove; 308: Raised edge;

[0046] 309: Isolation mat;

[0047] The insulating pad 6 includes:

[0048] 601: Wire bonding notch;

[0049] The shielding substrate 7 includes:

[0050] 701: First chamber; 702: Circuit board;

[0051] 703: External cable; 704: Cable tray.

[0052] 705: Threading hole; Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below.

[0054] To address the problem of limited sensitivity improvement caused by fixed installation dimensions in the background technology, this invention proposes a pressure-boosting low-frequency pressure hydrophone: by arranging an array of pressure surfaces along the extension direction of the hydrophone, the effective pressure-bearing area of ​​the disc-shaped hydrophone is increased, thereby overcoming size constraints and improving sensitivity.

[0055] There are two main physical mechanisms for receiving acoustic signals using piezoelectric ceramic hydrophones: mass-based (inertial) reception and acoustic transmission-based (direct coupling) reception. Mass-based hydrophones form a mass-spring resonant system by adding a mass load to one end of the piezoelectric ceramic element, allowing the inertial force caused by sound pressure to directly act on the piezoelectric material, generating an electrical charge output. Acoustic transmission-based hydrophones, on the other hand, rely on the direct action of transmitted sound waves on the piezoelectric element, utilizing the material's thickness vibration mode to convert sound pressure changes into electrical signals. In the field of low-frequency acoustic monitoring (especially in the 10Hz-5kHz frequency band), the mass-based structure exhibits significant advantages. In contrast, acoustic transmission-based hydrophones suffer from a sharp decrease in sensitivity at low frequencies due to a lack of mechanical gain and the high acoustic impedance mismatch between water and piezoelectric materials, making it difficult to detect weak underwater leakage signals.

[0056] This invention creatively employs an optimized mass block design scheme. By arranging an array of pressure surfaces along the extension direction of the hydrophone, the effective pressure-bearing area of ​​the disc-shaped hydrophone is increased, thereby overcoming size constraints and improving sensitivity. This enables high-sensitivity, wide dynamic range low-frequency acoustic monitoring suitable for water supply networks, oil and gas pipelines, and underwater structures. In particular, it has excellent detection capabilities for characteristic acoustic signals generated by minute leaks in the 100-5000Hz frequency band.

[0057] To achieve the aforementioned objectives, and in conjunction with Figures 1 to 5, this invention discloses a pressurized low-frequency pressure hydrophone, which mainly includes: a front housing 1, a rear cover 2, a pressurizing component 3, and a sensing element 4. The pressurizing component 3 and the sensing element 4 are connected and housed together inside the front housing 1, working together to monitor underwater sound pressure fluctuations; the rear cover 2 is threadedly attached to the front housing 1.

[0058] As shown in Figures 2 and 3, the pressurizing component 3 is provided with a first pressure surface 301, a second pressure surface 302, and a third pressure surface 303, each with a conical surface. The third pressure surface 303 is connected to the second pressure surface 302 via a first connecting shaft 304, and the second pressure surface 302 is connected to the first pressure surface 301 via a second connecting shaft 305. The connection method can be self-adhesive or welding. The three pressure surfaces have the same outer diameter, and the cone angle of their conical surfaces is consistent, preferably 90°. The main function of the pressure surfaces is to receive the pressure of the acoustic radiation waves from the pipeline. The purpose of the cone angle design is to significantly improve the effective sound pressure capture efficiency when facing non-axial incident sound waves (e.g., side acoustic radiation).

[0059] Specifically, using a pressure surface with a 90° cone apex angle can significantly improve the response to lateral sound radiation while maintaining structural simplicity, enabling lateral sound pressure to be converted into normal force acting on the elastic adhesive layer 306 as effectively as possible. Although this cone angle design is not the theoretically "maximum possible" response angle (the theoretical maximum response depends on a directional vertical surface), the 90° cone surface is a highly optimized design choice in terms of balancing multi-directional sensitivity, engineering feasibility, and response uniformity.

[0060] One end of the first pressure surface 301 is bonded and fixed to one side of the sensitive element 4 by an elastic adhesive layer 306; a sealing groove 307 is provided on the side of the first pressure surface 301, which is used to install the first sealing ring 5. The bottom end faces of the second pressure surface 302 and the third pressure surface 303 are both provided with adhesive isolation pads 309, which are used to prevent the bottom end faces from contacting water.

[0061] As shown in Figures 3 and 4, an insulating pad 6 and a shielding substrate 7 are sequentially mounted on the other side of the sensitive element 4. The other end of the shielding substrate 7 abuts against the inner wall of the rear cover 2, forming an axial positioning fit between the two. The insulating pad 6 is used to achieve isolation and insulation between the sensitive element 4 and the shielding substrate 7, and is preferably made of ceramic material. The insulating pad 6 has a solder wire notch 601 to provide clearance for the solder wires and solder joints of the sensitive element 4.

[0062] The shielding substrate 7 is made of a conductive material (e.g., brass), and its main function is to achieve electromagnetic shielding while also providing axial support for the sensitive element 4. The shielding substrate 7 has a first chamber 701 inside to accommodate the circuit board 702. A through hole 705 and a wiring groove 704 are provided on the outer side of the shielding substrate 7 at positions corresponding to the wire bonding notch 601. Signal lines (not shown in the figure) soldered to the sensitive element 4 pass sequentially through the wire bonding notch 601, the wiring groove 704, and the through hole 705, and connect to the circuit board 702 within the first chamber 701.

[0063] The external cable 703 connects to the first chamber 701 via the tail end of the rear cover 2, achieving electrical connection with the circuit board 702. The rear cover 2 is equipped with a second sealing ring 8 and a locking nut 9, used for sealing and securing the external cable 10, respectively. The O-ring sealing structure formed by the second sealing ring 8 achieves an IP68 waterproof rating, ensuring a reliable seal at the rear end of the hydrophone. The rear cover 2 is threaded onto the front shell 1, and threadlocker is used for auxiliary sealing, further improving the overall sealing performance. To achieve better shielding and weather resistance, the front shell 1, rear cover 2, and locking nut 9 are all made of stainless steel.

[0064] As shown in Figure 5 (cross-sectional view of front shell 1), the front shell 1 is provided with multiple signal windows 101 and two isolation plates 102; wherein, the opening position of each signal window 101 corresponds to the side of the first pressure surface 301 and the second pressure surface 302, so that the side of the first pressure surface 301 and the second pressure surface 302 can directly contact the fluid. This is also the core reason for the conical design of the pressure surface, since the first pressure surface 301 and the second pressure surface 302, as intermediate pressure surfaces, are mainly used to receive the side-incident acoustic radiation waves.

[0065] The two isolation plates 102 are designed separately to support and bond the isolation pad 309. The isolation pad 309 prevents the bottom surfaces of the second pressure surface 302 and the third pressure surface 303 from contacting water, thus avoiding the bottom surfaces from bearing fluid pressure. A through hole is provided in the middle of the isolation plate 102 for the first connecting shaft 304 and the second connecting shaft 305 to pass through. To facilitate the assembly of the pressurizing component 3, the two isolation plates 102 are welded together using the welding surface 105 after the pressurizing component 3 is installed in place.

[0066] The front housing 1 is also provided with a circular sealing surface 103 and a second chamber 104 inside, which are coaxially distributed, and the size of the second chamber 104 is slightly larger than the size of the circular sealing surface 103; the first sealing ring 5 on the pressurizing component 3 is adapted to contact the circular sealing surface 103 to achieve sealing of the front end of the hydrophone; the edge of the pressurizing component 3 is provided with a protruding edge 308 (as shown in Figure 3), which engages with the end face of the second chamber 104 during assembly to ensure the installation posture of the pressurizing component 3.

[0067] In addition, the outer periphery of the front housing 1 is provided with an external thread 106, the size of which is adapted to the thread specification of the hydrophone installation position; after the size of the external thread 106 is determined, the selection of the sensitive element 4 must be based on it, and its outer diameter is limited by the structural size of the external thread 106.

[0068] Preferably, the insulating pad 309 is made of a material with an elastic modulus significantly lower than that of the elastic adhesive layer 306. In this embodiment of the invention, the insulating pad 309 is specifically made of flexible silicone rubber, preferably a silicone rubber product with a Shore A hardness of 55~65 degrees and a Young's modulus of 9.0~18.0 MPa, such as Dow Corning SILASTIC™ DY 32-336 U Silicone Rubber; the elastic adhesive layer 306 is specifically made of rigid polyurethane (PU) adhesive, preferably Permabond UR5100 series two-component polyurethane structural adhesive, with a Shore D hardness ≥80 degrees and an elastic modulus E=0.8GPa, which is much higher than the elastic modulus of the aforementioned silicone rubber. The core technical purpose of this selection design is as follows: On the one hand, when the pressurizing component 3 vibrates under sound pressure excitation, its vibration response characteristics are mainly dominated by the mechanical properties of the elastic adhesive layer 306, and the mechanical interference of the isolation pad 309 on vibration transmission is negligible due to its significantly lower elastic modulus; on the other hand, the isolation pad 309 realizes the unilateral sound pressure receiving function of each pressure surface through structural constraints, so that each pressure surface only bears the sound pressure load in a single direction, and then vibrates in a directional manner along the preset direction, ensuring that the sound pressure signal is accurately and without distortion transmitted to the sensitive element.

[0069] As the core functional unit of the booster component 3, the three interconnected pressure surfaces and the elastic adhesive layer 306 together constitute a "mass-spring" resonant system. The three pressure surfaces form the "mass" of the system, and the elastic adhesive layer 306 forms the "spring." Traditional designs typically use only a single pressure surface. This embodiment of the invention creatively employs an array-type pressure surface design, effectively increasing the sound pressure receiving area. Specifically, this embodiment uses three pressure surfaces: a first pressure surface 301, a second pressure surface 302, and a third pressure surface 303. Let the total mass of the three pressure surfaces be m, the thickness of the elastic adhesive layer 306 be d, its area be S, and its elastic modulus be E. The natural frequency of this resonant system is calculated using the following formula:

[0070] (1)

[0071] In this embodiment of the invention, the hydrophone operates at low frequencies, requiring normal operation in the 10Hz-5kHz frequency band. Engineering requirements typically include:

[0072] (2)

[0073] In the formula, The operating frequency is used. To be conservative, we take 5 times as the standard for "much greater than", and apply formula (1) to this.

[0074] Substituting into formula (2), we get:

[0075] (3)

[0076] Summarized as follows:

[0077] (4)

[0078] In order for the hydrophone to meet the operating requirements of the low frequency range (10Hz-5kHz), the thickness d of the elastic adhesive layer 306 and the mass m of the pressure surface must meet the requirements of the above inequality (4).

[0079] Preferably, it can be further deduced from inequality (4): when the elastic modulus E and area S of the elastic adhesive layer 306 are both determined, the larger the total mass m of the pressure surface, the smaller the maximum allowable thickness d of the elastic adhesive layer 306. However, the thickness d should not be too small, especially when the elastic adhesive layer 306 uses rigid PU adhesive, an excessively thin adhesive layer is prone to causing difficulties in construction operations, air bubbles inside the adhesive layer, or uneven adhesive layer thickness and other process problems.

[0080] In this embodiment of the invention, the bonding thickness of the elastic adhesive layer 306 is preferably 0.20~0.30mm; if the selected rigid PU adhesive layer meets the following requirements: diameter 15mm (for calculating area S), d=0.3mm, E=0.8GPa, according to the inequality (4), the total mass m of the pressure surface is approximately 19g, that is, under these parameter conditions, the total mass of the pressure surface shall not exceed 19g. In this embodiment of the invention, the pressure surface is preferably made of low-density, high-strength PEEK (polyether ether ketone) material, whose quality characteristics meet the above-mentioned constraints. PEEK is chosen as the material for the pressure surface of the pressurizing component 3 because it possesses low density, good rigidity, excellent corrosion resistance, reliable electrical insulation, and acoustic impedance characteristics close to that of water. This not only significantly reduces the total system mass m, but also allows for a thicker rigid PU adhesive layer (i.e., increased thickness d) while ensuring the system's natural frequency remains at the design high value, greatly reducing the difficulty of process implementation and improving the product's structural reliability. Simultaneously, this material effectively improves sound pressure transmission efficiency, reduces sound signal reflection, and avoids electrical interference easily generated by metal materials, making it a preferred material for the pressure surface of high-performance hydrophone arrays.

[0081] The other end of the elastic adhesive layer 306 is directly bonded to the sensitive element 4. The sensitive element 4 is a piezoelectric ceramic, specifically a disc-type piezoelectric ceramic that vibrates in the thickness direction (i.e., thickness expansion mode, d33 mode), specifically a PZT-5H disc. As the sensitive element 4, the output signal of the piezoelectric ceramic is proportional to the mechanical force it receives. This mechanical force originates from the spring force applied to the piezoelectric ceramic after the sound pressure is transmitted through three pressure surfaces and deformed by the elastic adhesive layer (rigid PU adhesive).

[0082] The following section will explain in detail the magnitude of the force on piezoelectric ceramics, starting from a mechanical model.

[0083] In this embodiment of the invention, the third pressure surface 303 is located at the end of the hydrophone, and it is assumed that the sound wave pressure it receives is P, and its effective cross-sectional area is... Therefore, its effective sound pressure can be simply described as: F1 = P* *cos( t) (that is, the pressure pointing to the sensitive element 4), which is also the pressure value that a conventional design can receive. Similarly, assuming that the acoustic pressure received by the first pressure surface 302 and the second pressure surface 303 is P (for ease of calculation, the influence of the structure is ignored, and the pressure is still taken as P), the effective cross-sectional area is Therefore, the total effective sound pressure on both surfaces can be simply described as: F2 = 2 * P * *cos( t); then the resultant external sound pressure force is:

[0084] (5)

[0085] Where w is the angular frequency, This represents the amplitude (maximum value) of the force.

[0086] The stiffness of the elastic adhesive layer is k, specifically k = ES / d, and the system's equation of motion is (including the damping system, where c represents the damping coefficient):

[0087] m + c + = (6)

[0088] in, This represents the displacement of the pressure surface. For speed, It is acceleration.

[0089] The piezoelectric ceramic is directly bonded to the other end of the elastic adhesive layer 306; therefore, the force it experiences is the restoring force generated by the elastic adhesive layer 306. Under harmonic excitation, the steady-state displacement solution of equation (6) is: The displacement amplitude is:

[0090] (7)

[0091] Therefore, the amplitude of the force on the piezoelectric ceramic is (where...) (Indicates damping ratio):

[0092] (8)

[0093] According to formula (8), when Time (ideal work area) denominator .

[0094] In the original single pressure surface (area) Based on this, two new areas with an area of After the pressure surface is reached, the force enhancement factor of the piezoelectric ceramic is R, which is given by the following formula:

[0095] (9)

[0096] As can be seen from equation (9), the force enhancement factor R depends on... The extreme case is However, this is impossible because different pressure surfaces need to be connected and force transmitted. In this embodiment of the invention, the connection is achieved through a first connecting shaft 304 and a second connecting shaft 305. Preferably, the two connecting shafts have the same diameter and a cross-sectional area not exceeding [a certain value]. 1 / 20. Assume the cross-sectional area of ​​the connecting shaft is... 1 / 20, then Substituting into equation (8), we get R = 2.9. That is, the amplitude of the force on the piezoelectric ceramic is increased to 2.9 times the original value, which is equivalent to an increase of 190% in force.

[0097] It should be noted that the above calculations assume that the sound pressure on the three pressure surfaces is the same. In reality, structural obstruction is inevitable, and the sound pressure values ​​on the two middle pressure surfaces will be slightly lower than those on the end pressure surface. In addition, the addition of new pressure surfaces will increase the total mass and may reduce the natural frequency. It is necessary to ensure that the conditions of equation (2) are still met, otherwise the force transmission efficiency will be reduced. In this embodiment of the invention, low-density PEEK material is used to reduce the total weight as much as possible.

[0098] Unless otherwise specified, the model numbers of the various devices in this embodiment of the invention are not limited, and any device that can perform the above functions is acceptable.

[0099] Those skilled in the art will understand that the accompanying drawings are merely schematic diagrams of a preferred embodiment, and the sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0100] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A pressurized low-frequency pressure hydrophone, characterized in that, The hydrophone includes: a front housing, a rear cover, a pressurizing component, and a sensing element. The pressurization component is connected to the sensitive element and is housed together inside the front shell. The two work together to monitor underwater sound pressure fluctuations. The rear cover is assembled to the front shell by a threaded connection. The pressurizing component is provided with a first pressure surface, a second pressure surface and a third pressure surface; the third pressure surface is connected to the second pressure surface through a first connecting shaft, and the second pressure surface is connected to the first pressure surface through a second connecting shaft. The pressure surfaces are used to receive the pressure of the acoustic radiation waves from the pipeline. The first pressure surface, the second pressure surface, and the third pressure surface all have conical surfaces; the connection method is selected from bonding or welding; the outer diameters of the three pressure surfaces are the same, and the cone angles of the conical surfaces are consistent; One end of the first pressure surface is bonded and fixed to one side of the sensitive element by an elastic adhesive layer; a sealing groove is provided on the side of the first pressure surface for installing the first sealing ring; the bottom end faces of the second and third pressure surfaces are both provided with adhesive isolation pads. The front housing is provided with multiple signal windows and two isolation plates; The opening position of each signal window corresponds to the side of the first pressure surface and the second pressure surface, so that the side of the first pressure surface and the second pressure surface are in direct contact with the fluid. The two isolation plates are designed to be separate and used to support and fix the isolation pads. The isolation pads prevent the bottom surfaces of the second and third pressure surfaces from coming into contact with water. The front housing is further provided with a circular sealing surface and a second chamber, and the size of the second chamber is larger than the size of the circular sealing surface; the first sealing ring on the pressurizing component is adapted to contact the circular sealing surface to achieve sealing of the front end of the hydrophone; the edge of the pressurizing component is provided with a protruding edge, which engages with the end face of the second chamber for positioning during assembly; The thickness of the elastic adhesive layer and the quality of the pressure surface must meet the following requirements: ; The force enhancement factor R of piezoelectric ceramics is given by the following formula: ； Where d is the thickness, S is the area, E is the elastic modulus, and m is the total mass. For operating frequency, and Where P is the effective cross-sectional area and P is the sound pressure.

2. The pressurized low-frequency pressure hydrophone according to claim 1, characterized in that, An insulating pad and a shielding substrate are sequentially assembled on the other side of the sensitive element. The other end of the shielding substrate is supported against the inner wall of the rear cover, and the two form an axial positioning fit.

3. A pressurized low-frequency pressure hydrophone according to claim 2, characterized in that, The shielding substrate has a first chamber inside for accommodating the circuit board, and the outer side of the shielding substrate has a through hole and a wiring groove at the position corresponding to the bonding wire notch. The signal lines soldered to the sensitive components pass through the solder wire notch, the wiring groove, and the wire hole in sequence, and are connected to the circuit board in the first chamber.

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