1. The utility model provides a resistant hydrostatic pressure optic fibre hydrophone based on piston which characterized in that: the device comprises a rigid cylinder, an end cover arranged at one end of the rigid cylinder, a pre-tightening device arranged at the central position of the end cover, a sound-sensitive diaphragm arranged at the other end of the rigid cylinder, and a diaphragm chamber arranged in the rigid cylinder and connected with the sound-sensitive diaphragm, wherein piston cavities are also arranged in the rigid cylinder at equal intervals along the circumferential direction of the rigid cylinder, one end of each piston cavity is communicated with the diaphragm chamber through a communicating chamber, the other end of each piston cavity is communicated with corresponding corrugated pipes, the number of the corrugated pipes is equal to that of the piston cavities, the end parts of the corrugated pipes are connected with the end cover, and water inlets are formed in the joints of the end parts of the corrugated pipes and the end cover; and a fiber grating is arranged in the rigid cylinder, a first tail fiber of the fiber grating is connected with the pre-tightening device, and a second tail fiber of the fiber grating is connected with the acoustic sensitive membrane.

2. The piston-based hydrostatic pressure resistant fiber optic hydrophone of claim 1, wherein: the piston cavity comprises a piston body, a piston ring, a piston connecting rod and a piston connecting rod locking bolt, wherein the piston ring is a metal elastic ring, one end of the piston connecting rod locking bolt is positioned in the piston body, the other end of the piston connecting rod locking bolt is connected with the piston connecting rod, and the locking bolt and the piston connecting rod play a role in connecting the piston and the corrugated pipe.

3. A piston-based hydrostatic-pressure-resistant fiber optic hydrophone according to claim 1 or 2, wherein: the sound sensitive membrane is an elastic round stainless steel sheet.

4. A piston-based hydrostatic-pressure-resistant fiber optic hydrophone according to claim 1 or 2, wherein: water enters the corrugated pipe through the water inlet hole, the corrugated pipe is stretched and deformed due to the existence of water pressure, the water in the corrugated pipe pushes the piston system connected with the corrugated pipe to move, the piston system compresses gas in the piston cavity, the compressed gas enters the diaphragm chamber through the communication hole, meanwhile, one side of the acoustic sensitive diaphragm is also acted by the water pressure, and the pressure at the two sides of the diaphragm is balanced; when a sound pressure signal acts on the sound sensitive diaphragm, the sound sensitive diaphragm deforms to cause the axial deformation of the fiber bragg grating, and sound signal information is obtained according to the deformation of the fiber bragg grating.

5. The piston-based hydrostatic pressure resistant fiber optic hydrophone of claim 3, wherein: water enters the corrugated pipe through the water inlet hole, the corrugated pipe is stretched and deformed due to the existence of water pressure, the water in the corrugated pipe pushes the piston system connected with the corrugated pipe to move, the piston system compresses gas in the piston cavity, the compressed gas enters the diaphragm chamber through the communication hole, meanwhile, one side of the acoustic sensitive diaphragm is also acted by the water pressure, and the pressure at the two sides of the diaphragm is balanced; when a sound pressure signal acts on the sound sensitive diaphragm, the sound sensitive diaphragm deforms to cause the axial deformation of the fiber bragg grating, and sound signal information is obtained according to the deformation of the fiber bragg grating.

Background

The optical fiber hydrophone is an instrument for detecting sound in water by utilizing the light transmission characteristic of an optical fiber and the modulation effect generated by the action of the sound pressure of the surrounding environment. The existing optical fiber hydrophone mainly has intensity modulation type, interference type, optical fiber grating type and the like, and the optical fiber grating type hydrophone has wide application prospect in the fields of ship-borne underwater acoustic measurement, rapid warning of islands and ports and the like due to the advantages of high sensitivity, small volume, easiness in wavelength division multiplexing and the like.

Because the fiber grating hydrophone is a wavelength sensitive sensor, the wavelength of the fiber grating changes along with the pressure intensity, and the fiber grating hydrophone which is suitable for a large-depth working environment is less researched at present. Therefore, how to improve the hydrostatic pressure resistance while ensuring the measurement sensitivity under high pressure is a key problem that needs to be solved in the application of the fiber grating hydrophone.

Common ways to improve the hydrostatic pressure resistance include increasing the structural strength of the hydrophone, opening the hydrophone structure, compensating the pressure, and the like.

In the aspect of increasing the structural strength of the hydrophone, Lidongming et al designs an elastic diaphragm sensitization probe, the static pressure resistance of the structure depends on the rigidity of the elastic diaphragm, and the hydrostatic pressure resistance of the hydrophone is improved by optimizing the structure. When the water pressure is sufficiently high, the diaphragm is compressed and deformed. The ability to withstand static pressure in this manner depends largely on the material properties and can reduce the hydrophone sensitivity (ref, leeming, navy, gehulian, zhangli. high sensitivity acceleration-canceling distributed feedback active fiber grating hydrophone study [ J ] chinese laser, 2012,39(03):139- > 145.).

In the aspect of hydrophone structure trompil, land prays to and looks the people of waiting to design a resistant static pressure hydrophone probe of rigidity section of thick bamboo trompil, and the cavity and the external world intercommunication of diaphragm both sides guarantee that the diaphragm both sides water pressure is balanced. The fiber grating is easily damaged when exposed to external fluid due to the open hole (ref, Lu pray, yellow and handstand, Wang Yun cloud. a static pressure distribution resistant feedback fiber laser hydrophone probe design [ J ] applied optics, 2020,41(02): 428-.

In applying the pressure compensation structure, Kuttan Chandrika Unnikrishnan et al integrate the pressure compensation structure inside the hydrophone in the form of a slider cell. The hydrostatic pressure resistance of the hydrophone depends on the moving distance of the sliding block in the sliding block chamber, and under the action of a long time, the sliding block is abraded inevitably caused by frequent contact of the sliding block and the sliding block chamber, so that the hydrostatic pressure resistance is weakened. In addition, due to The lack of a cushioning structure, The slides within The hydrophone are susceptible to damage from The large impact forces experienced by strong water currents (see Chandrika Unnikrishnan Kuttan, Pallayil Venugolan, Lim Kian Meng, Chew Chye Heng. pressure compensated fiber laser hydrophone: modeling and experiment [ J ]. The Journal of The acoustic Society of America,2013,134 (4)).

Steven Goodman et al propose a balanced hydrostatic pressure type fiber grating hydrophone structure with an air bag. This hydrophone has a complex structure, low reliability, large air bag volume, and is easily destroyed in a complex underwater environment, which greatly reduces the reliability of the hydrophone, and is not conducive to miniaturization of the hydrophone structure (reference, Steven Goodman, Alexei Tikhomirov, Scott focus.

Disclosure of Invention

The invention aims to make up for the defects of the prior art, and provides a fiber grating hydrophone which is small in size, strong in static pressure resistance and has a buffering function by utilizing the advantages of strong air tightness, strong compensation pressure, corrosion resistance and the like of a piston and a corrugated pipe for balancing hydrostatic pressure.

The purpose of the invention is realized as follows: the device comprises a rigid cylinder, an end cover arranged at one end of the rigid cylinder, a pre-tightening device arranged at the central position of the end cover, a sound-sensitive diaphragm arranged at the other end of the rigid cylinder, and a diaphragm chamber arranged in the rigid cylinder and connected with the sound-sensitive diaphragm, wherein piston cavities are also arranged in the rigid cylinder at equal intervals along the circumferential direction of the rigid cylinder, one end of each piston cavity is communicated with the diaphragm chamber through a communicating chamber, the other end of each piston cavity is communicated with corresponding corrugated pipes, the number of the corrugated pipes is equal to that of the piston cavities, the end parts of the corrugated pipes are connected with the end cover, and water inlets are formed in the joints of the end parts of the corrugated pipes and the end cover; and a fiber grating is arranged in the rigid cylinder, a first tail fiber of the fiber grating is connected with the pre-tightening device, and a second tail fiber of the fiber grating is connected with the acoustic sensitive membrane.

The invention also includes such structural features:

1. the piston cavity comprises a piston body, a piston ring, a piston connecting rod and a piston connecting rod locking bolt, wherein the piston ring is a metal elastic ring, one end of the piston connecting rod locking bolt is positioned in the piston body, the other end of the piston connecting rod locking bolt is connected with the piston connecting rod, and the locking bolt and the piston connecting rod play a role in connecting the piston and the corrugated pipe.

2. The sound sensitive membrane is an elastic round stainless steel sheet.

3. Water enters the corrugated pipe through the water inlet hole, the corrugated pipe is stretched and deformed due to the existence of water pressure, the water in the corrugated pipe pushes the piston system connected with the corrugated pipe to move, the piston system compresses gas in the piston cavity, the compressed gas enters the diaphragm chamber through the communication hole, meanwhile, one side of the acoustic sensitive diaphragm is also acted by the water pressure, and the pressure at the two sides of the diaphragm is balanced; when a sound pressure signal acts on the sound sensitive diaphragm, the sound sensitive diaphragm deforms to cause the axial deformation of the fiber bragg grating, and sound signal information is obtained according to the deformation of the fiber bragg grating.

Compared with the prior art, the invention has the beneficial effects that: the fiber grating hydrophone provided by the embodiment of the invention abandons the structure of an air bag and a sliding block. When the water pressure changes, the pressures on the left side and the right side of the piston are unbalanced, the water pressure pushes the piston to move forwards until the pressures on the two sides of the piston are balanced, and therefore pressure compensation is achieved. In addition, the corrugated pipe structure has a buffering effect, and when strong water flow impacts on the hydrophone suddenly, the damage of the water flow impact on the hydrophone structure can be effectively avoided due to the existence of the corrugated pipe structure. The corrugated pipe device is adopted, so that the separation of the piston device and water is effectively ensured, and the phenomenon that the inner wall of the piston cavity is corroded due to long-time contact with water, so that the piston cavity loses air tightness is avoided. In addition, the specific number of the piston cavities can be adjusted according to the hydrostatic pressure resistance required to be compensated under the specific use environment, and large hydrostatic pressure compensation can be realized under the combined action of the piston body, the elastic piston ring and a plurality of piston cavity structures.

Drawings

FIG. 1 is a schematic front view of a hydrophone structure;

in the figure, 010 fiber grating, 020 sound sensitive diaphragm, 030 rigid cylinder, 040 diaphragm chamber, 050 communication chamber, 060 piston system, 070 piston cavity, 071 corrugated pipe, 080 end cover, 081 water inlet hole and 090 pre-tightening device.

FIG. 2 is a left side view of a hydrophone structure;

FIG. 3 is a schematic view of the piston assembly;

in the figure, piston chamber 070, first type 072 seal ring, second type 073 seal ring, first type 074 seal ring groove, second type 075 seal ring groove, 076 piston body, 077 piston connecting rod locking bolt, 078 piston connecting rod.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

With reference to fig. 1 to 3, the present invention provides a fiber grating hydrophone, which mainly includes four parts: the device comprises a supporting protection unit, an acoustic signal detection unit, a pressure compensation unit and a buffer unit. The supporting and protecting unit comprises a corrosion-resistant metal rigid cylinder and a pre-tightening device, wherein the pre-tightening device is positioned in the center of one end of the rigid cylinder. The buffering unit is composed of a corrugated pipe and an end cover, the corrugated pipe is made of rubber materials, the end cover is designed on the front end face of the corrugated pipe, and a water inlet hole is formed in the end cover and can prevent sundries from entering and blocking the corrugated pipe. The pressure compensation unit comprises a piston system and a piston cavity, wherein the piston device consists of a piston body, a piston ring tightly surrounding a piston groove on the surface of the piston body, a piston connecting rod and a piston connecting rod locking bolt. The piston ring is a metal elastic ring with larger outward expansion deformation, one end of a piston connecting rod locking bolt is positioned in the piston body, the other end of the piston connecting rod locking bolt is connected with the piston connecting rod, and the locking bolt and the piston connecting rod can play a role in connecting the piston and the corrugated pipe. The acoustic signal detection unit comprises a fiber grating and an acoustic sensitive membrane, wherein the acoustic sensitive membrane is made of a corrosion-resistant round metal sheet, and can convert a sound pressure signal into the deformation of the fiber grating; the rigid cylinder is of a cylindrical structure, the fiber bragg grating is arranged in the right center of the interior of the rigid cylinder, one end of the fiber bragg grating is connected to the acoustic sensitive film, and the other end of the fiber bragg grating is connected to the pre-tensioning device. The N piston cavities are arranged in the rigid cylinder along the axial direction of the rigid cylinder and distributed around the optical fiber with the spatial position difference of 360 DEG/N. The end cover and the corrugated pipe are arranged at the leftmost end of the piston cavity, the corrugated pipe is connected with the piston system through a piston connecting rod, two piston rings in the piston system are arranged on the piston body, and the piston cavity is communicated with the diaphragm chamber through the communication hole. The sound-sensitive diaphragm is arranged on one side of the rigid cylinder and used for deforming under the action of sound pressure, and the diaphragm chamber close to the sound-sensitive diaphragm can provide space for the expansion of the sound-sensitive diaphragm.

The rigid cylinder is provided with an opening; the piston cavity is positioned in the cylindrical rigid cylinder to form a plurality of uniformly arranged cavities; the corrugated pipe is arranged at the port of the piston cavity and is used for playing a role in buffering when the hydrophone is impacted by water flow; the piston system is arranged at the rear end of the corrugated pipe; the communication hole is arranged behind the piston cavity and is connected with the piston cavity; the pre-tightening device is arranged at the center of one end of the rigid cylinder; the acoustic sensitive diaphragm is arranged at the other end of the rigid cylinder; the diaphragm chamber is arranged inside the rigid cylinder and is connected with the sound-sensitive diaphragm; and the fiber bragg grating is arranged in the rigid cylinder, a first tail fiber of the fiber bragg grating is connected with the pre-tightening device at one end of the rigid cylinder, and a second tail fiber of the fiber bragg grating is connected with the acoustic sensitive membrane at the other end of the rigid cylinder. The end cover is arranged at the front end of the corrugated pipe, and the water inlet hole is formed in the end cover, so that water flow can conveniently enter the corrugated pipe and meanwhile sundries can be prevented from entering the corrugated pipe. The back of the piston cavity is provided with a communication hole and a diaphragm chamber in sequence. The cavity formed by connecting the piston cavity, the intercommunicating pore and the diaphragm chamber penetrates through the whole rigid cylinder. The piston cavity is of a cylindrical structure, and the corrugated pipe is arranged in the piston cavity along the axial direction of the piston cavity. The piston cavity, the communication hole and the diaphragm chamber are arranged in the rigid cylinder along the axial direction of the rigid cylinder.

Referring to fig. 1, there is shown an overall structure of a hydrophone according to the present invention.

Wherein 080 is an end cover, 081 is a water inlet hole on the end cover, 071 is a corrugated pipe, and a rigid cylinder 030 is a cylindrical cylinder with one open end, and generally a metal material with good rigidity and corrosion resistance, such as titanium alloy, is used; the pre-tightening device 090 is made of invar steel and is installed at the open end of the supporting rigid cylinder 030; the acoustic sensitive diaphragm 020, which is generally an elastic round stainless steel sheet, is arranged at the other end of the rigid cylinder 030; the piston device 060 is located inside the piston cavity 070, the piston cavity 070 is connected with the diaphragm chamber 040 through the communicating chamber 050, the fiber bragg grating 010 mounted at the inner axis of the rigid cylinder 030 is a fiber bragg grating, one end of the fiber bragg grating 010 penetrates through the center of the acoustic sensitive diaphragm 020 and is used for sensing sound pressure, certain prestress can be applied to the fiber bragg grating 010 through the tightening device 090 when the fiber bragg grating 010 is mounted, and tail fibers of the fiber bragg grating 010 are led out through the tightening device 090.

Referring to fig. 3, the overall structure of the piston system provided by the present invention is shown.

The piston body 076 is made of an invar steel material and is arranged in the piston cavity 070, a piston connecting rod 078 and a piston connecting rod locking bolt 077 matched with the piston connecting rod are arranged along the axis of the piston body 076, a first 0-type sealing ring groove 074 and a second 0-type sealing ring groove 075 are arranged on the cylindrical surface of the piston body 076, a first 0-type sealing ring 072 is arranged in the first 0-type sealing ring groove 074, a second 0-type sealing ring 073 is arranged in the second 0-type sealing ring groove 075, and sealing effect is realized by means of sliding friction between the first 0-type sealing ring 072 and the second 0-type sealing ring 073 and the piston cavity 070. The piston rod 078 is primarily intended to facilitate future replacement of the piston assembly 060.

The working principle of the fiber grating hydrophone based on the piston balanced static pressure provided by the invention is as follows:

water enters the corrugated pipe 071 through a water inlet 081 on the front end cover 080 of the corrugated pipe 071, when enough water is in the corrugated pipe 071, the corrugated pipe 071 is elongated, the water in the corrugated pipe 071 pushes the piston system 060 to move forward, the gas in the piston cavity 070 is compressed, when the gas pressure in the piston cavity 070 is consistent with the external water pressure, the piston system 060 stops moving, and at the moment, the pressures at two ends of the sound-sensitive membrane 020 are consistent. When an acoustic signal acts on the acoustic sensitive membrane 020, the acoustic sensitive membrane 020 is deformed, the fiber grating 010 is axially stretched, the wavelength of the light wave reflected by the fiber grating 010 changes, and the sound pressure signal information can be detected by detecting the wavelength variation.

In summary, the invention provides an optical fiber hydrophone, which comprises a cylindrical rigid cylinder, a corrugated pipe, a piston cavity, a piston system, a communication hole, a diaphragm chamber, an acoustic sensitive diaphragm and an optical fiber grating. A plurality of piston cavities which are uniformly arranged are arranged in the rigid cylinder along the axis direction, the corrugated pipe is arranged at one end in each piston cavity, and the piston system is connected with the corrugated pipe through a piston connecting rod to realize hydrostatic pressure resistance compensation. The piston cavity is connected with the diaphragm chamber through a communication hole, and the outer end of the diaphragm chamber is provided with a diaphragm; and the fiber bragg grating is arranged at the inner axis of the rigid cylinder, one end of the fiber bragg grating is connected with the sound-sensitive membrane, and the other end of the fiber bragg grating is connected with the pre-tightening device in the rigid cylinder. The invention realizes high sensitivity and static pressure balance on smaller volume; the hydrophone can be buffered and protected by utilizing the corrugated pipe structure.