Noise reduction device and system suitable for hydrophone self-noise measurement

Abstract

The invention provides a noise reduction device suitable for self-noise measurement of a hydrophone. The noise reduction device comprises a shell, a connecting module, a damping module, an air pressure control module and a signal transmission module, the connecting module comprises an adapter port; the damping module is located at the bottom of the shell, and the air pressure control module and the signal transmission module are arranged on the shell through an adapter. The shell comprises an end cover, a side wall and an inner cavity defined by the side wall and the end cover, the damping module comprises a vibration isolator and a bottom base, the air pressure control module comprises a first valve and a second valve, and the signal transmission module comprises a cable connector and a cable; and the adapter is fixedly connected to the side wall of the shell. Through the multi-stage vibration isolation structure, isolation of environment vibration noise is achieved, and the influence of environment vibration on noise testing can be effectively reduced; the device is simple in structure, and can be used for measuring the equivalent self-noise of the vector hydrophone and the self-noise of the sound pressure hydrophone at the same time.

Description

Technical Field

[0001] The present application relates to the field of mechanical structure design, and in particular, to a noise reduction device and system suitable for measuring self-noise of a hydrophone. Background Art

[0002] In hydroacoustic engineering, with the continuous development of engineering technology and the deepening of research, the means of obtaining hydroacoustic signals are also increasing. There are not only sound pressure hydrophones for obtaining scalar signals, but also vector hydrophones for obtaining the vibration velocity of water particles. The performance of hydrophones is subject to a basic limitation, namely the equivalent self-noise of the hydrophone. In order to better evaluate the performance of the hydrophone, it is necessary to measure the equivalent self-noise of the hydrophone and characterize it with the equivalent self-noise sound pressure spectrum (level) or the equivalent self-noise acceleration spectrum (level).

[0003] Self-noise is an important indicator that affects the dynamic range of the vector hydrophone, and it is also an important indicator that people pay attention to. The accuracy of self-noise measurement directly affects the evaluation results of the vector hydrophone performance. The accuracy of vector hydrophone measurement is usually greatly affected by the test environment. It is not only affected by the noise signal of the test environment, but also by the vibration of the test environment. Therefore, when measuring the self-noise of the vector hydrophone, it is necessary to isolate both the noise interference of the test environment and the vibration interference of the test environment. In order to effectively reduce the interference of the test environment and obtain reliable self-noise data, researchers have conducted various attempts and explorations.

[0004] In the 1970s, B&K developed a device for measuring the self-noise of microphones. In 2008, British scholars used a folding pendulum as a shock absorber to measure the self-noise of accelerometers. This structure can effectively block the ground vibration noise in the range of 4-20Hz. In 2012, American researchers used the stable shock-absorbing platform of the National Institute of Standards and Technology to test ultra-low frequency noise. The platform is composed of heavy steel plates and suspended by high-strength rubber bands. RESON has developed a set of hydrophone low self-noise measurement equipment. The test tank adopts a steel cylindrical structure. During the test, the tank is placed on the foam and the air in the tank is pumped out to make the tank close to a vacuum state. Researchers at the US Naval Laboratory also used a steel tank and vacuum treatment to achieve the measurement of low noise and vibration sensor background noise. GB / 4128-1995 describes the measurement method of equivalent noise pressure of hydrophones and gives a schematic diagram of the test device.

[0005] Patent No. CN106124025A provides a calibration device and method for the equivalent self-noise acceleration spectrum level of a low-noise water volume hydrophone. This method requires a special hydroacoustic tube, two hydrophones and a dedicated signal processing method to achieve noise measurement.

[0006] Although the prior art can solve the problem of measuring hydrophone noise to a certain extent, it also has obvious shortcomings, such as either requiring dedicated equipment or only being able to measure the self-noise of the sound pressure hydrophone. Summary of the invention

[0007] In view of the defects in the prior art, the purpose of the present application is to provide a noise reduction device and system suitable for measuring the self-noise of a hydrophone.

[0008] According to the present application, a noise reduction device and system suitable for measuring the self-noise of a hydrophone includes: a housing, a connection module, a shock absorption module, an air pressure control module and a signal transmission module;

[0009] The connection module includes a transfer interface;

[0010] The shock absorbing module is located at the bottom of the housing, and the air pressure control module and the signal transmission module are both arranged on the housing through an adapter;

[0011] The housing comprises: an end cover, a side wall and an internal cavity surrounded by the side wall and the end cover; the shock absorbing module comprises: a vibration isolator and a bottom base; the air pressure control module comprises: a first valve and a second valve; the signal transmission module comprises: a cable connector and a cable line;

[0012] The transfer port is fixedly connected to the side wall of the shell, one end of the transfer port extends into the internal cavity, and the other end extends out of the side wall of the shell to communicate with the outside;

[0013] The portion of the first adapter extending out of the side wall of the housing is connected to the negative pressure pipe of the vacuum pump via a first valve arranged thereon;

[0014] One end of the second adapter extending out of the side wall of the housing is provided with a second valve and is connected to the atmosphere through the second valve;

[0015] A lead is provided at one end of the cable connector of the signal transmission module, the lead extends into the internal cavity and is connected to the signal transmission lead of the device under test, and the other end is connected to the cable;

[0016] The vibration reduction module comprises at least three vibration isolators, and a substrate is arranged between any adjacent vibration isolators.

[0017] Preferably, the air pressure control module further comprises: a vacuum gauge;

[0018] The vacuum gauge is connected to the internal cavity via an adapter.

[0019] Preferably, a high-density braided metal shielding sheath is provided outside the cable line, one end of the high-density braided metal shielding sheath is connected to the cable connector, and the other end is grounded.

[0020] Preferably, the shell side wall is a double-layer structure, the inner shell side wall and the outer shell side wall are nested and installed, and the corresponding openings are matched.

[0021] Preferably, the end cover comprises: an inner end cover and an outer end cover, the outer end cover is fixedly connected to the outer shell side wall via a flange, an inner end cover is arranged on the upper end of the inner side wall, and the inner shell side wall is fixedly connected to the inner end cover.

[0022] Preferably, the outer end cover and the outer shell side wall are both made of metal material.

[0023] Preferably, the inner end cover and the inner shell side wall are both made of copper material.

[0024] Preferably, the first valve and the second valve are both spherical valves.

[0025] Preferably, the adapter is fixedly connected to the housing by welding or bonding.

[0026] Preferably, the vibration isolator is an inflatable airbag structure.

[0027] Compared with the prior art, this application has the following beneficial effects:

[0028] 1. This application uses a multi-level vibration isolation structure to isolate environmental vibration noise, which can effectively reduce the impact of environmental vibration on noise testing.

[0029] 2. This application adopts a multifunctional integrated design with a simple structure, simple operation and easy engineering application. It can be used not only for measuring the equivalent self-noise spectrum level of a vector hydrophone, but also for measuring the self-noise of a sound pressure hydrophone. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0031] Figure 1 This application mainly embodies the overall structural schematic diagram of the noise reduction device suitable for measuring the self-noise of a hydrophone;

[0032] Figure 2 This application mainly embodies a flange structure schematic diagram of a noise reduction device suitable for measuring hydrophone self-noise.

[0033] As shown in the figure: 1. outer end cover; 2. outer side wall; 3. second valve; 4. second adapter; 5. vacuum gauge; 6. third adapter; 7. inner side wall; 8. first vibration isolator; 9. first substrate; 10. second vibration isolator; 11. second substrate; 12. third vibration isolator; 13. cable connector; 14. cable; 15. first adapter; 16. first valve; 17. cover plate; 18. first nut; 19. sealing ring; 201. flange; 202. second nut. DETAILED DESCRIPTION

[0034] The present application is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present application, but do not limit the present application in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present application. These all belong to the protection scope of the present application.

[0035] The noise reduction device and system for measuring the self-noise of a hydrophone provided by the present application include: a housing, a connection module, a shock absorbing module, an air pressure control module and a signal transmission module; the connection module includes an adapter; the shock absorbing module is located at the bottom of the housing, and the air pressure control module and the signal transmission module are both arranged on the housing through the adapter;

[0036] The housing comprises: an end cover, a side wall and an internal cavity surrounded by the side wall and the end cover; the shock absorbing module comprises: a vibration isolator and a bottom base; the air pressure control module comprises: a first valve 16 and a second valve 3; the signal transmission module comprises: a cable connector 13 and a cable 14;

[0037] The adapter is fixedly connected to the side wall of the shell, one end of the adapter extends into the internal cavity, and the other end extends out of the side wall of the shell to communicate with the outside world; the part of the first adapter 16 extending out of the side wall of the shell is connected to the negative pressure pipe of the vacuum pump through the first valve 16 arranged thereon; the end of the second adapter 4 extending out of the side wall of the shell is provided with a second valve 3 and connected to the atmosphere through the second valve 3;

[0038] The cable connector 13 of the signal transmission module is provided with a lead at one end, the lead extends into the internal cavity and is connected to the signal transmission lead of the device under test, and the other end is connected to the cable 14; the vibration reduction module includes at least three vibration isolators, and a substrate is provided between any adjacent vibration isolators. The air pressure control module also includes: a vacuum gauge 5; the vacuum gauge 5 is connected to the internal cavity through an adapter.

[0039] A high-density braided metal shielding sheath is disposed outside the cable line 14 , one end of the high-density braided metal shielding sheath is connected to the cable connector 13 , and the other end is grounded.

[0040] The shell side wall is a double-layer structure, the inner shell side wall and the outer shell side wall are nested and installed, and the corresponding openings match. The end cover includes: an inner end cover and an outer end cover 1, the outer end cover 1 is fixedly connected to the outer shell side wall through a flange, an inner end cover is arranged on the upper end of the inner side wall 7, and the inner shell side wall is fixedly connected to the inner end cover.

[0041] The outer end cover 1 and the outer shell side wall are both made of metal materials, and the inner end cover and the inner shell side wall are both made of copper materials. A platform that matches the outer end cover 1 is horizontally extended from the opening above the outer side wall 2. The platform is fixedly connected to the outer end cover 1 through a flange, and a sealing groove is opened on the platform.

[0042] The first valve 16 and the second valve 3 are both spherical valves. The transfer interface and the housing are fixedly connected by welding or bonding. The vibration isolator is an inflatable airbag structure.

[0043] Specifically, a feasible implementation method is provided for the present application as follows.

[0044] The sealing cover referred to below refers to the outer end cover, the sealed can referred to below refers to the outer side wall, the inner can body referred to below refers to the inner side wall, and the cover plate referred to below refers to the inner end cover.

[0045] The noise reduction device suitable for measuring the self-noise of a hydrophone provided by the present invention comprises: a sealing cover 1, a sealing tank body 2, a second valve 3, a second adapter 4, a vacuum gauge 5, a third adapter 6, an inner tank body 7, a first-stage vibration isolator 8, a base 9, a second-stage vibration isolator 10, a base 11, a third-stage vibration isolator 12, a cable connector 13, a cable 14, a first adapter 15, a first valve 16, a cover plate 17, screws 18, and a sealing ring 19.

[0046] The sealing cover 1 and the sealing tank body 2 form a first space.

[0047] The inner tank body 7 and the cover plate 17 form a second space, which is placed in the first space.

[0048] The flange has six evenly distributed screw holes 201 and one sealing groove 202 .

[0049] Furthermore, one end of the second adapter 4, the third adapter 6 and the first adapter 15 are welded to the sealed tank body 1 respectively, so that the first space can be connected to the external air through the second adapter 4, the third adapter 6 and the first adapter 15 respectively. The second valve 3 is connected to the second adapter 4 and sealed; the vacuum gauge 5 is connected to the third adapter 6 and sealed; the first valve 16 is connected to the first adapter 15 and sealed; to ensure no leakage. The cable connector 13 is fixed to the sealed tank body 2 and sealed, the lead wire enters the first space, and the other end is connected to the cable line 14. The cable 14 has a high-density braided metal shielding sheath on the outside, one end is connected to the cable connector 13, and the other end is connected to the grounding terminal of the test instrument. The inner tube body 7 is placed in the sealed tank body 2 and matches the corresponding position opening in the sealed tank body 2.

[0050] Place the third-stage vibration isolator 12 on the ground, adjust the air volume, and place the base 11 on the upper end of the third-stage vibration isolator 12; place the second-stage vibration isolator 10 on the base 11, adjust the air volume, and place the base 9 on the upper end of the second-stage vibration isolator 10; place the first-stage vibration isolator 8 on the base 9, adjust the air volume, and place the sealed tank body 2 on the upper end of the first-stage vibration isolator 8. Place the vector hydrophone to be measured in the inner tank body 7, and connect the signal line to the lead of the cable connector 13. Place the cover plate 17 at the opening of the inner tube body 7, place the sealing cover 1 on the upper end of the flange of the sealed tank body 2, and install the screws 18 in the corresponding holes.

[0051] Through the above embodiments, a low background noise test environment can be obtained, and the background noise acceleration noise spectrum level is lower than -140dB (0dB re 1m / s2)

[0052] The sealing cover 1 is recommended to be a circular flat plate or an arc-shaped folded edge cover, the diameter should generally be 300-500mm, and the thickness should be 5-20mm; mounting holes are evenly arranged on the circumference of the sealing cover 1, and the mounting holes are recommended to be through holes. The mounting holes can be connected to the outer edge of the sealing cover 1 or not, the number of through holes is about 4-12, and the hole diameter is approximately distributed between 5-12mm.

[0053] It is recommended that the sealed tank body 2 be configured as a hollow cylindrical structure with a bottom and an open top, with a wall thickness between 5-20mm, an internal space height between 300-800mm, and an outer diameter of the cylindrical structure of 300-500mm; the side wall of the sealed tank body 2 is provided with circular holes for installation with the second valve 4, the third adapter 6, the cable head 13 and the first adapter 15; the top opening is provided with a flange with a flange width of 20-100mm and a thickness of 5-20mm; the flange is provided with threaded through holes, which are evenly distributed along the circumference, with a number of 4-12, and a size of the threaded through holes of M5-M12; the inner edge side of the flange is provided with sealing grooves, with a number of 1-3 and a width of 3-10mm.

[0054] The second valve 4, the third adapter 6 and the first adapter 15 are metal round tubes with an inner diameter of 6-15 mm. They are located on the side of the sealed tank body 2, one end of which is connected to the inside of the metal tank body 2 and is connected to the inside of the metal tank body 2 by bonding or welding; the other end has a mounting thread.

[0055] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0056] The above describes the specific embodiments of the present application. It should be understood that the present application is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the substantive content of the present application. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be arbitrarily combined with each other.

Claims

1. A noise reduction device suitable for measuring hydrophone self-noise, characterized in that: include: Housing, connection module, shock absorption module, air pressure control module and signal transmission module; The connection module includes a transfer interface; The shock absorbing module is located at the bottom of the housing, and the air pressure control module and the signal transmission module are both arranged on the housing through an adapter; The housing comprises an end cover, a side wall and an internal cavity surrounded by the side wall and the end cover; the shock absorbing module comprises a vibration isolator and a bottom base; the air pressure control module comprises a first valve (16) and a second valve (3); and the signal transmission module comprises a cable connector (13) and a cable (14); The transfer port is fixedly connected to the side wall of the shell, one end of the transfer port extends into the internal cavity, and the other end extends out of the side wall of the shell to communicate with the outside; The portion of the first transfer port (16) extending out of the side wall of the housing is connected to the negative pressure pipe of the vacuum pump via a first valve (16) arranged thereon; One end of the second transfer port (4) extending out of the side wall of the housing is provided with a second valve (3) and is connected to the atmosphere through the second valve (3); A lead is provided at one end of the cable connector (13) of the signal transmission module, the lead extends into the internal cavity and is connected to the signal transmission lead of the device to be tested, and the other end is connected to the cable (14); The vibration reduction module includes at least three vibration isolators, and a substrate is arranged between any adjacent vibration isolators.

2. The noise reduction device for measuring hydrophone self-noise according to claim 1, characterized in that: The air pressure control module further comprises: a vacuum gauge (5); The vacuum gauge (5) is connected to the internal cavity via an adapter.

3. The noise reduction device for measuring hydrophone self-noise according to claim 2, characterized in that: The cable (14) is provided with a high-density braided metal shielding sheath on the outside, one end of the high-density braided metal shielding sheath is connected to the cable connector (13), and the other end is grounded.

4. The noise reduction device for measuring hydrophone self-noise according to claim 1, characterized in that: The shell side wall is a double-layer structure, the inner shell side wall and the outer shell side wall are nested and installed, and the corresponding positions have matching openings.

5. The noise reduction device for measuring hydrophone self-noise according to claim 4, characterized in that: The end cover comprises: an inner layer end cover and an outer layer end cover (1), the outer layer end cover (1) is fixedly connected to the outer layer shell side wall via a flange, an inner layer end cover is arranged at the upper end of the inner layer side wall (7), and the inner layer shell side wall is fixedly connected to the inner layer end cover.

6. The noise reduction device for measuring hydrophone self-noise according to claim 1, characterized in that: The outer end cover (1) and the side wall of the outer shell are both made of metal material, and the inner end cover and the side wall of the inner shell are both made of copper material.

7. The noise reduction device for measuring hydrophone self-noise according to claim 1, characterized in that: A platform that cooperates with the outer end cover (1) is horizontally extended from the upper opening of the outer side wall (2); the platform is fixedly connected to the outer end cover (1) via a flange, and a sealing groove is provided on the platform.

8. The noise reduction device for measuring hydrophone self-noise according to claim 1, characterized in that: The first valve (16) and the second valve (3) are both spherical valves.

9. The noise reduction device for measuring hydrophone self-noise according to claim 1, characterized in that: The adapter is fixedly connected to the shell by welding or bonding.

10. The noise reduction device for measuring hydrophone self-noise according to claim 1, characterized in that: The vibration isolator is an inflatable airbag structure.

Images