1. A combi-sensor for fluid parameter sensing in a pipeline, the combi-sensor comprising:

a housing configured to have a streamlined outer surface;

the fiber grating temperature sensor is arranged inside the shell and can detect the temperature of liquid in the environment where the composite sensor is located;

the fiber bragg grating temperature and pressure sensor is arranged on the shell and can detect comprehensive data of the temperature and the pressure of liquid in the environment where the composite sensor is located;

and the fiber grating pressure pulsation sensor is arranged on the shell and can detect the pressure fluctuation of the liquid in the environment where the composite sensor is positioned.

2. The composite sensor of claim 1, wherein the housing comprises a first housing, a second housing, and a connecting cover, the first housing being located on one side of the connecting cover and fixedly connected to the connecting cover, the second housing being located on the other side of the connecting cover and fixedly connected to the connecting cover.

3. The composite sensor of claim 2, wherein the first housing is provided with a through hole;

the composite sensor further comprises an elastic sheet arranged at the through hole, and the elastic sheet is connected with the first shell in a sealing mode and completely closes the through hole;

the fiber bragg grating pressure pulsation sensor comprises a first fiber bragg grating pressure pulsation sensor fixed to the outer side of the elastic sheet and a second fiber bragg grating pressure pulsation sensor correspondingly fixed to the inner side of the elastic sheet, so that the pressure fluctuation is detected through fluctuation of a difference value between data detected by the first fiber bragg grating pressure pulsation sensor and data detected by the second fiber bragg grating pressure pulsation sensor.

4. The composite sensor according to claim 3, further comprising a balloon disposed in the first housing, wherein elastic material is filled between the balloon and the housing and between the balloon and the connection cover, so as to encapsulate the balloon in the elastic material to form an elastic body;

the elastic sheet is not in contact with the air bag or the elastic substance, so that a cavity is formed between the air bag or the elastic substance and the connecting cover, and hydrogen or helium with the pressure of 0.1MPa is filled in the cavity to ensure that the elastic sheet has a certain back pressure effect on the outside; the space of the cavity is used for ensuring that the elastic piece does not touch the elastic body when being deformed maximally.

5. The composite sensor of claim 2, further comprising a thermally conductive silicone oil filled in the second housing, the thermally conductive silicone oil submerging the fiber grating temperature sensor so as to enhance temperature consistency between the housing and the fiber grating temperature sensor.

6. The composite sensor of claim 5, further comprising a thermally conductive sheet and first and second fixing plates disposed within and fixedly connected to the second housing,

one side wall of the heat conducting fin is fixedly connected with the first fixing plate so as to ensure that the heat conducting fin and the first fixing plate can conduct heat in time; the other side wall of the heat conducting fin and the second fixing plate can be connected together in a relatively movable mode, so that the other side wall of the heat conducting fin can move freely when the heat conducting fin is deformed when being heated;

the fiber grating temperature sensor is fixedly connected with the heat-conducting strip, so that the longitudinal deformation of the grating can be increased along with the heated extension of the heat-conducting strip, and the heat-conducting strip has a sensitization effect on the fiber grating temperature sensor.

7. The composite sensor of claim 6, further comprising a thermally conductive wire extending through the second housing, the thermally conductive wire being fixedly connected to the first mounting plate such that the thermally conductive wire establishes a rapid thermal transfer path between a fluid in an environment in which the composite sensor is located and the first mounting plate.

8. The composite sensor of any of claims 1-7, further comprising a first fiber grating flow rate sensor and a second fiber grating flow rate sensor,

the first fiber grating flow velocity sensor and the second fiber grating flow velocity sensor are symmetrically arranged on the outer side of the shell along the axis of the shell, so that the flow velocity and the flow direction or the variation of the flow velocity of the liquid in the environment where the composite sensor is located can be detected through the difference value between the data detected by the first fiber grating flow velocity sensor and the data detected by the second fiber grating flow velocity sensor.

9. The composite sensor according to claim 8, further comprising a plurality of optical fibers penetrating the housing, wherein the optical fibers are made of the same material and have the same specification, and each optical fiber has a grating recorded on a specific portion of the housing or the surface thereof, and the characteristic values of the gratings are the same, thereby forming the fiber grating temperature sensor, the fiber grating temperature pressure sensor, the fiber grating pressure pulsation sensor, the first fiber grating flow rate sensor, and the second fiber grating flow rate sensor;

the composite sensor further comprises an optical fiber connector connected with one end of the optical fiber far away from the sensor.

10. The compound sensor of claim 9, wherein the housing is configured in a football or ellipsoid shape.

Background

In a hydraulic transmission system, the flow rate (kinetic energy) of the medium is low, the potential energy generated is relatively low, and it is not considered that the power is transmitted only by the pressure energy of the working medium, namely the hydrostatic transmission. With the application of artificial intelligence in the fields of engineering machinery and the like, electronic information can be well amplified into mechanical action through a hydraulic system as a hydraulic system with small force and large force. Therefore, the hydraulic system is an important intermediate link in the operation of the intelligent machine. In order to ensure the normal operation of the hydraulic system, the operation parameters of the hydraulic system are usually monitored in real time, so that the operation condition of the hydraulic system can be known in time, and early warning can be given in time before the hydraulic system fails; or when the hydraulic system has faults, analysis parameters are provided for timely diagnosing the types and reasons of the faults.

In hydrostatic transmissions, the flow of liquid in the line corresponds to the pressure difference between the flow regions. The flow rate in the pipeline can correspond to the flow speed, so that the flow rate in the pipeline can be obtained by checking the pressure difference. Thus, the detection of the three parameters of temperature, pressure and flow of the hydraulic system can be reduced to the detection of the two parameters of temperature and pressure. The fiber grating sensors have the characteristics of electromagnetic interference resistance, small size and light weight, can detect two parameters of temperature and pressure, and can form a distributed detection matrix through series connection of a plurality of fiber grating sensors, so that the number of detection lines can be greatly reduced.

At present, most sensors for detecting temperature, pressure or flow parameters of the hydraulic system are in a single parameter form, and diagnosis of a fault of the hydraulic system can accurately judge the type or the reason of the fault only by depending on operating parameters such as temperature, pressure and flow inside the hydraulic system. However, if all the sensors for detecting each of the above parameters are disposed in the hydraulic system, a plurality of detection points must be disposed in the hydraulic pipeline, and sometimes a plurality of detection process holes need to be opened in the hydraulic pipeline, thereby increasing the risk of leakage of the hydraulic pipeline. And because the space of the hydraulic system of the engineering machinery and the mining machinery is limited, and the total volume of the sensors is large, it is difficult to arrange detection instruments related to temperature, pressure, flow and flow pulsation at key positions simultaneously for diagnosing hydraulic faults. Moreover, if sensors for detecting temperature, pressure and flow are arranged in the hydraulic pipeline at the same time, the detection circuit (circuit for connecting the sensors) is more, the structure is complex, and the appearance of the hydraulic system is affected. In the prior art, only one of the temperature, the pressure and the flow of the hydraulic system is detected, so that the fault of the hydraulic system is difficult to diagnose by the single detection technology at present.

With the development of intelligent engineering machinery, an integrated hydraulic parameter detection sensor capable of detecting comprehensive information such as oil pressure, oil temperature, flow velocity or pressure pulsation of key parts of a hydraulic system is urgently needed, so that intelligent analysis and troubleshooting of the hydraulic system of the engineering machinery can be realized through advanced computer technology, photoelectronic technology, communication technology and the like.

Therefore, it is urgent and important to develop an integrated hydraulic parameter comprehensive detection sensor which can be built in the fluid and has small disturbance to the fluid flow.

Disclosure of Invention

In order to solve the above problems in the prior art, that is, to solve the problem that the parameters of the hydraulic system of the engineering machinery are difficult to be acquired by a few sensor systems, the present disclosure provides a composite sensor for detecting the parameters of the fluid in the pipeline, which can connect a plurality of composite sensors in series to form a system parameter acquisition array by using the wavelength division multiplexing technology in the hydraulic system, so as to solve the problem of the comprehensive acquisition of the parameters of the hydraulic system of the engineering machinery. The composite sensor includes:

a housing configured to have a streamlined outer surface;

the fiber grating temperature sensor is arranged inside the shell and can detect the temperature of liquid in the environment where the composite sensor is located;

the fiber bragg grating temperature and pressure sensor is arranged on the shell and can detect the comprehensive data of the temperature and the pressure of the liquid in the environment where the composite sensor is located;

and the fiber grating pressure pulsation sensor is arranged on the shell and can detect the pressure fluctuation of the liquid in the environment where the composite sensor is located.

Optionally, the housing includes a first housing, a second housing and a connecting cover, the first housing is located on one side of the connecting cover and is fixedly connected with the connecting cover, and the second housing is located on the other side of the connecting cover and is fixedly connected with the connecting cover.

Optionally, a through hole is arranged on the first shell; the composite sensor also comprises an elastic sheet arranged at the through hole, and the elastic sheet is connected with the first shell in a sealing way and completely closes the through hole; the fiber grating pressure pulsation sensor comprises a first fiber grating pressure pulsation sensor fixed to the outer side of the elastic sheet and a second fiber grating pressure pulsation sensor correspondingly fixed to the inner side of the elastic sheet, so that the pressure fluctuation is detected through fluctuation of a difference value between data detected by the first fiber grating pressure pulsation sensor and data detected by the second fiber grating pressure pulsation sensor.

Optionally, the composite sensor further includes an air bag disposed in the first housing, and elastic materials are filled between the air bag and the housing and between the air bag and the connecting cover, so as to encapsulate the air bag in the elastic materials to form an elastic body. The elastic sheet is not in contact with the air bag or the elastic substance, so that a cavity is formed between the air bag or the elastic substance and the connecting cover, and hydrogen or helium with the pressure of 0.1MPa is filled into the cavity to ensure that the elastic sheet has a certain back pressure effect on the outside; the spacing of the cavities is used for ensuring that the elastic sheet does not touch the elastic body when being deformed maximally.

Optionally, the composite sensor further includes a heat conductive silicone oil filled in the second housing, and the heat conductive silicone oil immerses the fiber grating temperature sensor so as to enhance the temperature consistency between the housing and the fiber grating temperature sensor.

Optionally, the composite sensor further includes a heat conducting fin, and a first fixing plate and a second fixing plate which are disposed in the second housing and fixedly connected to the second housing, wherein a side wall of the heat conducting fin is fixedly connected to the first fixing plate, so as to ensure that heat conduction can be performed between the heat conducting fin and the first fixing plate in time; the other side wall of the heat conducting fin and the second fixing plate can be connected together in a relatively movable manner, so that the other end of the heat conducting fin can freely move when the heat conducting fin is heated and deformed; the fiber grating temperature sensor is fixedly connected with the heat-conducting strip, so that the longitudinal deformation of the grating can be increased along with the heated extension of the heat-conducting strip, and the heat-conducting strip plays a role in sensitizing the fiber grating temperature sensor.

Optionally, the composite sensor further includes a heat conducting wire penetrating through the second housing, and the heat conducting wire is fixedly connected to the first fixing plate, so that the heat conducting wire can establish a rapid heat transfer channel between the liquid in the environment where the composite sensor is located and the first fixing plate.

Optionally, the composite sensor further includes a first fiber grating flow rate sensor and a second fiber grating flow rate sensor, which are symmetrically disposed on the outer side of the housing along the axis of the housing, so as to detect the flow rate and the flow direction or the variation of the flow rate of the liquid in the environment where the composite sensor is located through the difference between the data detected by the first fiber grating flow rate sensor and the data detected by the second fiber grating flow rate sensor.

Optionally, the composite sensor further includes a plurality of optical fibers penetrating through the housing, the optical fibers are made of the same material and have the same specification, each optical fiber is recorded with a grating in the housing or on a specific portion of the surface of the housing, and the characteristic values of the gratings are the same, so that the fiber grating temperature sensor, the fiber grating temperature pressure sensor, the fiber grating pressure pulsation sensor, the first fiber grating flow velocity sensor and the second fiber grating flow velocity sensor are formed; the composite sensor further comprises a connector connected with one end, far away from the sensor, of the optical fiber.

Optionally, the shell is shaped like a football or an ellipse.

Based on the foregoing description, it can be understood by those skilled in the art that, in the foregoing technical solutions of the present disclosure, by providing the housing with a streamlined outer surface, the resistance of the composite sensor to the detection liquid can be effectively reduced; the fiber bragg grating temperature sensor is arranged inside the shell, so that the composite sensor can not be interfered by the pressure of liquid in the environment where the sensor is located; the fiber bragg grating temperature and pressure sensor is arranged on the shell, so that the composite sensor can detect comprehensive data of temperature and pressure of liquid in the environment through the fiber bragg grating temperature and pressure sensor and then convert the data into detection of a pressure value by combining with a temperature detection numerical value; the fiber bragg grating pressure pulsation sensor is arranged on the shell, so that the composite sensor can be combined with the first fiber bragg grating pressure pulsation sensor and the second fiber bragg grating pressure pulsation sensor, and the pressure fluctuation of liquid in the environment can be detected through the fluctuation quantity and the time difference of the data difference between the two fiber bragg grating pressure pulsation sensors in a certain center. Thus, the compound sensor of the present disclosure is not only capable of detecting the pressure, temperature and pressure pulsations of the liquid in the environment, but also may be built into the pipeline. Meanwhile, the plurality of sensors are arranged on or in the shell in a centralized mode, so that a plurality of measuring points of comprehensive parameters needed by the hydraulic system are reduced to the measuring points which can measure pressure, temperature and pressure pulsation only by arranging one measuring point, and the risk of leakage of a hydraulic pipeline is greatly reduced.

Further, by symmetrically arranging the first fiber grating flow velocity sensor and the second fiber grating flow velocity sensor on the outer side of the shell along the axis of the shell, and the first fiber bragg grating flow velocity sensor and the second fiber bragg grating flow velocity sensor are positioned in the flowing direction of flowing liquid in the using process, and ensure that the fiber bragg grating characteristic values in the first fiber bragg grating flow velocity sensor and the second fiber bragg grating flow velocity sensor are the same, thereby the composite sensor can eliminate the influence of temperature factors in the same temperature environment field through the difference between the data detected by the first fiber bragg grating flow velocity sensor and the data detected by the second fiber bragg grating flow velocity sensor, the pressure difference of the liquid in the environment can be obtained, the flow speed of the liquid at the sensor can be obtained through the pressure difference, and then the flow of the liquid at the sensor is converted by combining the flow area; the fluctuation of the flow rate can also be detected by the fluctuation of the pressure difference; the direction of flow rate can also be measured by a change in the direction of the pressure difference.

Furthermore, the sensors are all arranged into the fiber grating sensors, so that the composite sensor has the characteristics of electromagnetic interference resistance, small size and light weight, and the performance is better, and the plurality of fiber grating sensors can be used as detection lines through one optical cable (comprising a plurality of optical fibers), so that compared with the prior art, the number of the detection lines is greatly reduced, and the detection wiring of the hydraulic system is more attractive. Therefore, the engineering machinery with the compound sensor can systematically acquire the parameters of the hydraulic system.

Drawings

Preferred embodiments of the present disclosure are described below, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a cross-sectional view of a coupling assembly in a preferred embodiment of the present disclosure;

FIG. 2 is an exploded view of the structure of a composite sensor (optical fiber not shown) in a preferred embodiment of the disclosure;

FIG. 3 is a front view of a composite sensor (optical fiber not shown) in a preferred embodiment of the present disclosure;

FIG. 4 is a cross-sectional view taken along A-A of FIG. 3;

fig. 5 is a sectional view taken along the direction B-B in fig. 3.

List of reference numerals:

1. a four-way pipe joint; 11. a first joint; 12. a second joint; 13. a third joint; 14. a fourth joint;

2. a composite sensor; 201. a housing; 2011. a first housing; 2012. a second housing; 2013. a connecting cover; 202. a fiber grating temperature sensor; 203. a fiber grating temperature and pressure sensor; 204. a first fiber grating pressure pulsation sensor; 205. a second fiber grating pressure pulsation sensor; 206. a first fiber bragg grating flow velocity sensor; 207. a second fiber bragg grating flow velocity sensor; 208. an elastic sheet; 209. an elastomer; 2091. an air bag; 2092. an elastomeric substance; 210. a heat conductive sheet; 211. heat conducting wires; 212. a first fixing plate; 213. a second fixing plate; 214. a first optical fiber group; 215. a second optical fiber group; 216. a first connector; 217. a second connector; 218. a cavity;

3. a first sealing plug;

4. a second sealing plug;

5. and (5) sealing the structure.

Detailed Description

It should be understood by those skilled in the art that the embodiments described below are only preferred embodiments of the present disclosure, which are intended to explain the technical principles of the present disclosure, and do not represent that the technical principles of the present disclosure can be implemented only by the preferred embodiments, and thus the preferred embodiments do not limit the scope of the present disclosure. All other embodiments that can be derived by one of ordinary skill in the art from the preferred embodiments provided by the disclosure without undue experimentation will still fall within the scope of the disclosure.

It should be noted that in the description of the present disclosure, the terms "center", "upper", "lower", "top", "bottom", "left", "right", "vertical", "horizontal", "inner", "outer", and the like, which indicate directions or positional relationships, are based on the directions or positional relationships shown in the drawings, which are merely for convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present disclosure. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

Furthermore, it should be noted that, in the description of the present disclosure, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as being fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present disclosure can be understood by those skilled in the art as appropriate.

As shown in fig. 1, in the preferred embodiment of the present disclosure, the pipe joint assembly includes a four-way pipe joint 1, a composite sensor 2, a first sealing plug 3, a second sealing plug 4, and a sealing structure 5. The composite sensor 2 is arranged in the four-way pipe joint 1 and is used for detecting the temperature, pressure, pulsation and flow speed of liquid in the four-way pipe joint 1. The first sealing plug 3, the second sealing plug 4 and the sealing structure 5 jointly fix the composite sensor 2 on the four-way pipe joint 1 in a sealing mode, and have certain shock absorption and shock resistance effects.

With continued reference to fig. 1, the four-way pipe joint 1 includes a first joint 11, a second joint 12 aligned with each other, and a third joint 13, a fourth joint 14 aligned with each other. Wherein the first joint 11 and the second joint 12 are blocked and thus completely closed by the first sealing plug 3, the second sealing plug 4 and the sealing structure 5, and the third joint 13 and the fourth joint 14 are used for connecting lines and communicating liquid.

As shown in fig. 1 and 2, the composite sensor 2 includes a housing 201, a fiber grating temperature sensor 202, a fiber grating temperature pressure sensor 203, a first fiber grating pressure pulsation sensor 204, a second fiber grating pressure pulsation sensor 205, a first fiber grating flow rate sensor 206, a second fiber grating flow rate sensor 207, an elastic sheet 208, an elastic body 209, a heat conduction sheet 210, a heat conduction wire 211, a first fixing plate 212, a second fixing plate 213, a first optical fiber group 214, a second optical fiber group 215, a first connection head 216, and a second connection head 217.

As shown in fig. 1, one end of the housing 201 is inserted into the first joint 11 and fixedly connected to the first joint 11 by the sealing structure 5, and the other end of the housing 201 is inserted into the second joint 12 and fixedly connected to the second joint 12 by the sealing structure 5, so that the housing 201 is fixed to the four-way pipe joint 1. It will be appreciated by those skilled in the art that where the seal 5 is capable of sealingly securing the housing 201 within the four-way pipe joint 1, the seal 5 may be of any feasible construction, such as a material such as rubber or plastic, or a composite of rubber or plastic with metal protection, or a split or semi-split construction for installation and sealing.

As shown in fig. 2, the fiber grating temperature sensor 202 is disposed inside the housing 201, and is capable of detecting the temperature of the liquid in the four-way pipe joint 1. As can be understood by those skilled in the art, the fiber grating temperature sensor 202 is disposed inside the housing 201, so that the pressure of the external liquid can be prevented from affecting the detection result of the fiber grating temperature sensor 202, and the detection accuracy of the fiber grating temperature sensor 202 is further ensured.

Continuing to refer to fig. 2, the fiber grating temperature and pressure sensor 203 is disposed on the housing 201 (specifically, disposed outside the housing 201; perpendicular to the flow direction or the pipe wall), and is capable of detecting the temperature and pressure of the liquid in the four-way pipe joint 1, and further capable of comparing the data detected by the fiber grating temperature and pressure sensor 203 and the data detected by the fiber grating temperature and pressure sensor 202, and obtaining the pressure of the liquid in the four-way pipe joint 1 according to the comparison data calibrated in advance corresponding to the fiber grating temperature and pressure sensor 203 through the pure temperature value detected by the fiber grating temperature and pressure sensor 202. The problem that the fiber grating sensor is sensitive to pressure and temperature in the prior art is solved, and the problem that the pressure detection range is influenced by linear calibration and is limited is solved. With continued reference to fig. 2, a first fiber grating pressure pulsation sensor 204 and a second fiber grating pressure pulsation sensor 205 are disposed on the housing 201 and are capable of detecting pulsation of the liquid in the four-way pipe joint 1.

As shown in fig. 1, the first fiber grating flow rate sensor 206 and the second fiber grating flow rate sensor 207 are both disposed on the housing 201 (specifically, disposed on the two outer sides of the housing 201, respectively, parallel to the flow direction or the pipeline), and the first fiber grating flow rate sensor 206 is aligned with the third connector 13, and the second fiber grating flow rate sensor 207 is aligned with the fourth connector 14. It can be understood by those skilled in the art that the flow rate and the variation of the flow direction or the flow rate of the liquid in the four-way pipe joint 1 can be determined by comparing the difference between the data detected by the first fiber grating flow rate sensor 206 and the data detected by the second fiber grating flow rate sensor 207. The flow rate of the liquid in the four-way pipe joint 1 can be calculated from the product of the flow rate and the cross-sectional area of the gap between the four-way pipe joint 1 and the composite sensor 2. Since the flow rate can be calculated by those skilled in the art according to the common general knowledge in the art, it will not be described herein too much. Those skilled in the art will also appreciate that in hydrostatic systems, neglecting the effects of potential energy and local pressure losses, the fluid flows as a pressure differential across the body, which accurately reflects the magnitude and direction of the fluid flow. Therefore, when the flowing liquid passes through the fluid winding (composite sensor), a pressure difference is generated between the front and the back of the fluid winding, and the flow speed and the direction can be determined by detecting the pressure difference.

With continued reference to fig. 1, the first optical fiber group 214 is armored (a protective layer is disposed on the outer side of the first optical fiber group 214), penetrates through the first connector 11, the first sealing plug 3 and the sealing structure 5, and is hermetically connected with the first sealing plug 3 and the sealing structure 5. In other words, the first optical fiber group 214 is hermetically connected to the first connector 11 through the first sealing plug 3 and the sealing structure 5. Further, one end of the first optical fiber group 214 is connected to the first connector 216 so as to be connected to an external optical cable through the first connector 216; the other end of the first fiber group 214 is connected to one end of each of the six fiber grating sensors, specifically, the first fiber group 214 includes six fibers, each of the fibers is a carrier of one fiber grating sensor, in other words, the fiber grating sensors are manufactured by recording gratings on the fibers, and grating characteristic values of the six fiber grating sensors in one composite sensor are the same (fiber core diameter is the same, recording depth is the same, grating period is the same, and grating length is the same), so that when the wavelength division multiplexing technology is used, positions of data sources obtained by the demodulation device are determined because the fiber grating characteristic values in the same composite sensor are the same. Since the wavelength division multiplexing technique is well known to those skilled in the art, it will not be described herein too much.

With continued reference to fig. 1, the second optical fiber set 215 is armored and extends through the second connector 12, the second sealing plug 4 and the sealing structure 5, and is sealingly connected to the second sealing plug 4 and the sealing structure 5. In other words, the second optical fiber group 215 is hermetically connected to the second connector 12 through the second sealing plug 4 and the sealing structure 5. Further, one end of the second optical fiber group 215 is connected to a second connector 217 to be connected to an external optical cable through the second connector 217; the other end of the second optical fiber group 215 is connected to the other ends of the six fiber grating sensors, and specifically, the second optical fiber group 215 includes six optical fibers, each of which is an extension of the optical fiber and belongs to the other end of the corresponding fiber grating sensor.

It should be noted that the foregoing descriptions of the terms "first fiber group 214" and "second fiber group 215" and the connection relationship between the two and each fiber grating sensor are only for convenience of description and for the understanding of the technical solutions by those skilled in the art. In practical use, the "first fiber group 214" and the "second fiber group 215" are actually the same fiber group, in other words, the fiber group consisting of 6 fibers penetrates the housing 201, and each fiber is inscribed with a grating at a specific portion in the housing 201, and thus the fiber grating temperature sensor 202, the fiber grating temperature pressure sensor 203, the first fiber grating pressure pulsation sensor 204, the second fiber grating pressure pulsation sensor 205, the first fiber grating flow rate sensor 206 and the second fiber grating flow rate sensor 207 are formed.

The specific structure of the composite sensor 2 will be described in detail with reference to fig. 2 to 5.

As shown in fig. 2, 4 and 5, the housing 201 has an oval spherical structure as a whole so as to reduce resistance to liquid flowing therethrough. Furthermore, the housing 21 may be provided in any other feasible configuration having a streamlined exterior, such as olive-shaped, fish-shaped, etc., as desired by those skilled in the art. Further, the housing 201 includes a first housing 2011, a second housing 2012, and a connection cover 2013. First housing 2011 and second housing 2012 can be detachably connected with connecting cover 2013, respectively, and in an assembled state, connecting cover 2013 can seal first housing 2011 and second housing 2012, so that a sealed space can be formed between first housing 2011 and connecting cover 2013, and a sealed space can be formed between second housing 2012 and connecting cover 2013.

Although not shown in the drawings, in a preferred embodiment of the present disclosure, the first housing 2011, the second housing 2012 and the connecting cover 2013 are all made of titanium alloy or aluminum alloy through stamping, or one skilled in the art may also stamp at least one of the first housing 2011, the second housing 2012 and the connecting cover 2013 as needed. Further, a through hole for mounting the elastic piece 208 is also provided on the first housing 2011.

As shown in fig. 4 and 5, the elastic piece 208 is embedded in a through hole on the first housing 2011, and a circumferential edge of the elastic piece 208 is connected with a side wall of the through hole in a sealing manner, or the elastic piece 208 is connected with the first housing 2011 in a sealing manner and closes the through hole. The first fiber grating pressure pulsation sensor 204 is fixedly connected to the outer side of the elastic sheet 208, the second fiber grating pressure pulsation sensor 205 is fixedly connected to the inner side of the elastic sheet 208, and the first fiber grating pressure pulsation sensor 204 and the second fiber grating pressure pulsation sensor 205 are symmetrically arranged relative to the elastic sheet 208, so that the first fiber grating pressure pulsation sensor 204 and the second fiber grating pressure pulsation sensor 205 can generate deformation with equal strain values but opposite directions along with the deformation of the elastic sheet 208.

Further, the elastic sheet 208 has good heat conduction characteristics, such as a heat conduction silicone sheet, a graphene film sheet, and the like, and a specific technical means for detecting the liquid pressure by the first fiber grating pressure pulsation sensor 204 and the second fiber grating pressure pulsation sensor 205 can be known by those skilled in the art by referring to a relevant principle on page 2155 of "journal of instruments and meters" (volume 39, phase 9) published in 2013, month 9. On this basis, a measure of compressive strain may then be obtained. The diaphragm is in direct contact with the working medium, so that the variation of the pressure strain measurement value can be obtained, and the fluctuation of the environmental pressure can be measured in time. The pressure measurement can be easily obtained by the existing computer processing technology by the variation of the pressure measurement value in the unit time, so that the description is not repeated.

With continued reference to fig. 4 and 5, the air bag 2091 is disposed within the first housing 2011 and the elastic substance 2092 is filled between the air bag 2091 and the first housing 2011 and the connection cap 2013 to encapsulate the air bag 2091 within the elastic substance 2092, forming the elastomer 209. The elastic piece 208 is not in contact with the airbag 2091 or the elastic substance 2092, so that a cavity 218 is formed between the elastic piece 208 and the elastic body 209, and hydrogen or helium gas with a pressure of 0.1MPa is filled in the cavity 218, and the elastic piece 208 is ensured not to contact with the elastic body 209 when being deformed maximally. It should be further noted that the hydrogen or helium gas filled in the cavity can play a certain back pressure role, so as to prevent the elastic sheet 208 from sinking at the standard atmospheric pressure, and meanwhile, the hydrogen or helium gas filled in the cavity can play a certain heat conduction and damping role, so as to prevent the elastic sheet 208 from being hot cracked or vibrating due to the elastic sheet 208 when the temperature or pressure of the liquid in the pipeline is disturbed, which has inconsistent shrinkage rate between the elastic sheet 208 and the first housing 2011.

Further, as required, the elastic substance 2092 provided between the air bag 2091 and the housing 201 may be an elastic filler made of a material such as rubber or resin. A skin may also be provided on the exterior of the housing 201, which skin is encapsulated outside the housing 201 and the optical fiber, the skin being compatible with the liquid in the conduit (the skin does not chemically react with the liquid).

With continued reference to fig. 4 and 5, the first fixing plate 212 and the second fixing plate 213 are respectively fixed in the second housing 2012, and specifically, the first fixing plate 212 is fixedly connected (e.g., welded or thermally bonded) to the second housing 2012 by welding or thermally conductive bonding or by first fixing posts (not shown), and the second fixing plate 213 is fixedly connected (e.g., welded or thermally bonded) to the first fixing plate 212 by welding or thermally conductive bonding or by second fixing posts (not shown). One end of the heat-conducting fin 210 is fixedly connected with the first fixing plate 212; the other end of the heat conduction plate 210 is movably connected to the second fixing plate 213, and specifically, the second fixing plate 213 is provided with a through hole (not shown) for allowing the heat conduction plate 210 to pass through, and the other end of the heat conduction plate 210 is inserted into the through hole, so that the heat conduction plate 210 can be freely deformed when being heated. Preferably, the heat conducting sheet 210 is an aluminum sheet capable of performing temperature measurement and sensitivity enhancement, and the aluminum sheet is an arc tile-shaped longitudinal strip, and the fiber grating temperature sensor 202 is tightly attached to the middle of the longitudinal axis of the arc tile-shaped aluminum sheet. Of course, the heat conducting sheet 210 can be configured into any other structure, such as a flat plate, a cylinder, etc. of copper sheet, zinc sheet, etc., as required by those skilled in the art.

The heat conducting wire 211 penetrates through a sidewall of the second housing 2012 (or penetrates through a gap between the connecting cover 2013 and the second housing 2012 to communicate with the outside), and has one end fixedly connected to the heat conducting strip 210 and the other end extending to the outside of the second housing 2012, so as to transfer heat of the liquid in the four-way pipe joint 1 to the heat conducting strip 210, and further, the heat is detected by the fiber bragg grating temperature sensor 202 fixed to the heat conducting strip 210. The fiber grating temperature sensor 202 can deform longitudinally along with the longitudinal deformation of the heat conducting sheet 210, so that the fiber grating temperature sensor 202 can increase the longitudinal deformation of the grating along with the heated extension of the heat conducting sheet 210, and the heat conducting sheet 210 can enhance the sensitivity of the fiber grating temperature sensor 202, so as to improve the measurement sensitivity of the fiber grating temperature sensor 202. Meanwhile, only one end of the heat conducting strip 210 (serving as a temperature measurement grating sensitization part) is fixed when longitudinally deforming, and the other end of the heat conducting strip can freely move, so that the interference of the internal thermal stress deformation caused by the heat conducting strip 210 expanding with heat and contracting with cold on the longitudinal signal of the fiber grating temperature sensor 202 is overcome, and the detection precision of the fiber grating temperature sensor 202 is improved.

In addition, one skilled in the art may also fixedly connect one end of the thermal conductive wire 211 located inside the second housing 2012 with the first fixing plate 212, so that the thermal conductive wire 211 firstly transfers heat in the external environment to the first fixing plate 212, and then the first fixing plate 212 transfers the heat to the thermal conductive sheet 210.

Although not shown in the figure, the second housing 2012 is further filled with heat conductive silicone oil, and the volume of the heat conductive silicone oil is between 1/2 and 4/5 of the spatial volume in the second housing 2012, so that the heat conductive silicone oil can also reliably transfer the heat of the liquid in the four-way pipe joint 1 to the heat conductive sheet 210, and ensure that no extra pressure strain is generated on the grating in the fiber grating temperature sensor 202 due to the expansion of excessive heat conductive silicone oil or the conduction action of external pressure. As will be appreciated by those skilled in the art, the thermal silicone oil flooding the thermal conductive sheet 210 enhances uniformity of heating of the thermal conductive sheet 210 and rapidity of heat transfer with the housing 201.

With continued reference to fig. 4 and 5, the fiber grating temperature and pressure sensor 203 is fixedly mounted on the outer side of the side wall of the second housing 2012 (preferably, disposed right under the elastic sheet 208 symmetrically, perpendicular to the fluid flow velocity direction, to ensure that the pressure and pressure fluctuation detection values can be referred to each other and are not affected by the dynamic fluid pressure), and the first fiber grating flow velocity sensor 206 and the second fiber grating flow velocity sensor 207 are symmetrically disposed on the circumferential surface of the connecting cover 2013 with respect to the long axis of the housing 201 (preferably, the planes of the first fiber grating flow velocity sensor 206 and the second fiber grating flow velocity sensor 207 are parallel to the fluid flow velocity direction).

Although not explicitly shown in the figure, the first fiber grating flow velocity sensor 206 and the second fiber grating flow velocity sensor 207 are fiber grating sensors with the same parameters, so that when the external environment (pressure or temperature) is the same, the data detected by the first fiber grating flow velocity sensor 206 and the second fiber grating flow velocity sensor 207 can be subtracted from each other, and the difference value can correspond to the flow velocity of the fluid, and meanwhile, the flow direction can be measured according to the positive and negative relationship of the difference value; meanwhile, the fluctuation condition of the flow velocity can be measured according to the fluctuation quantity of the difference subtraction value along with the time.

The operation of the combi sensor 2 will be briefly described with reference to fig. 1, 4 and 5.

When flowing liquid is introduced into the four-way pipe joint 3, the heat conducting wire 211 can transfer the heat of the liquid to the heat conducting sheet 210, so that the fiber grating temperature sensor 202 adhered to the heat conducting sheet 210 can increase the longitudinal deformation of the grating along with the heated extension of the heat conducting sheet 210, the heat conducting sheet 210 plays a role in sensitizing the fiber grating temperature sensor 202, and the fiber grating temperature sensor 202 obtains a temperature value and temperature sensitization precision. Specifically, the precise temperature of the liquid in the four-way pipe joint 3 is obtained by calculating the light wave change caused by the fiber grating temperature sensor 202 at this time. The cross influence of the environment pressure outside the shell on the detection result of the fiber bragg grating temperature sensor 202 is avoided.

Meanwhile, the deformation of the fiber grating temperature and pressure sensor 203 is also caused by the change of the temperature and pressure of the liquid in the four-way pipe joint 3, so that the comprehensive data of the temperature or pressure of the liquid in the four-way pipe joint 3 can be obtained according to the change of the relevant parameters of the light wave caused by the fiber grating temperature and pressure sensor 203 (for example, the characteristic wavelength center offset of grating transmitted light or reflected light or the change of stokes parameters). Then, by comparing the data detected by the fiber grating temperature and pressure sensor 203 and the data detected by the fiber grating temperature and pressure sensor 202, the pressure of the liquid in the four-way pipe joint 1 is obtained according to the corresponding data set pre-stored in the calibration. The situation that the pressure detection numerical value is difficult to extract due to the cross influence of the temperature of the liquid when the pressure of the liquid is measured by the grating center wavelength drift quantity for the fiber grating pressure sensor in the prior art is avoided.

Meanwhile, because the first fiber grating flow velocity sensor 206 and the second fiber grating flow velocity sensor 207 are simultaneously in the environment of the joint action of the liquid pressure and the temperature in the four-way pipe joint 3, and the grating characteristic values are the same, at this time, according to the difference value of the characteristic light wave signal changes caused by the first fiber grating flow velocity sensor 206 and the second fiber grating flow velocity sensor 207, the influence of the external environment pressure or temperature is avoided, so that, the flow velocity of the liquid in the four-way pipe joint 3 is calculated according to the difference value of the comprehensive data (including the values of the pressure and temperature signals) of the characteristic light signals detected by the first fiber grating flow velocity sensor 206 and the second fiber grating flow velocity sensor 207, and an auxiliary computer system is provided for the change situation of the flow velocity along with the time, the fluctuation of the flow rate can be calculated, and the flow direction of the liquid can be determined according to the positive and negative relations of the difference subtraction data.

Meanwhile, the liquid flowing in the four-way pipe joint 3 may pulsate (change in pressure at any moment), and therefore, the elastic sheet 208 changes periodically in deformation, so that the first fiber grating pressure pulsation sensor 204 and the second fiber grating pressure pulsation sensor 205 are forced to deform periodically, and then the real-time pressure pulsation changes of the liquid detected by the first fiber grating pressure pulsation sensor 204 and the second fiber grating pressure pulsation sensor 205 are respectively obtained according to the periodic changes of the characteristic light wave signals caused by the first fiber grating pressure pulsation sensor 204 and the second fiber grating pressure pulsation sensor 205. It will be appreciated by those skilled in the art that the first fiber grating pressure pulsation sensor 204 and the second fiber grating pressure pulsation sensor 205 disposed on either side of the elastic sheet 208 can also function to eliminate the cross-over effect of temperature on pressure sensing. Specifically, the elastic piece 208 can play a role in heat conduction, so that the difference between the values detected by the first fiber grating pressure pulsation sensor 204 and the second fiber grating pressure pulsation sensor 205 is the liquid pressure value outside the housing 201 (see the relevant principle on page 2155 of the journal of instruments and meters (volume 39, phase 9) published in 9 months of 2013, which utilizes the principle of reverse deformation difference reduction to effectively eliminate the problem of cross sensitivity of the fiber grating sensors with respect to temperature and strain, and further obtain a pressure measurement value which is not affected by temperature). On the basis, the principle that the diaphragm is directly (or indirectly) contacted with the working medium and can measure the fluctuation of the environmental pressure measurement value in time is utilized, and the pressure value can be determined to be pressure pulsation along with the time.

Of course, those skilled in the art can also accurately detect the fluctuation of the external liquid pressure by directly detecting the fluctuation amount of the difference between the data detected by the first fiber grating pressure pulsation sensor 204 and the data detected by the second fiber grating pressure pulsation sensor 205, if necessary.

In addition, in the actual use process, a plurality of composite sensors 2 can be connected in series by a person skilled in the art according to needs, so that each composite sensor 2 can respectively detect parameters at a plurality of positions in the liquid pipeline. In order to prevent the measurement data of the plurality of composite sensors 2 connected in series from being affected, the characteristic values of the gratings of the plurality of composite sensors 2 need to be set to be different. Specifically, the characteristic values of the gratings among the fiber grating sensors connected in series are set to be different, so that each of the multiple fiber grating sensors connected in series corresponds to a different characteristic grating, and each of the sensors (the fiber grating temperature sensor, the fiber grating temperature pressure sensor, the fiber grating pressure pulsation sensor, the first fiber grating flow velocity sensor and the second fiber grating flow velocity sensor) corresponding to each of the multiple composite sensors connected in series corresponds to each other, specifically, the fiber grating temperature sensor is connected in series with the fiber grating temperature sensor, the fiber grating temperature pressure sensor is connected in series with the fiber grating temperature pressure sensor, the fiber grating pressure pulsation sensor is connected in series with the fiber grating pressure pulsation sensor (the outer side and the inner side of the elastic sheet correspond to each other), the first fiber grating flow velocity sensor is connected in series with the first fiber grating flow velocity sensor, And the second fiber bragg grating flow velocity sensor is connected with the second fiber bragg grating flow velocity sensor in series so as to be convenient to check. Further, in order to facilitate data acquisition, a person skilled in the art may also make the characteristic values of the gratings of the plurality of fiber grating sensors on each composite sensor 2 the same as needed.

So far, the technical solutions of the present disclosure have been described in connection with the foregoing embodiments, but it is easily understood by those skilled in the art that the scope of the present disclosure is not limited to only these specific embodiments. The technical solutions in the above embodiments can be split and combined, and equivalent changes or substitutions can be made on related technical features by those skilled in the art without departing from the technical principles of the present disclosure, and any changes, equivalents, improvements, and the like made within the technical concept and/or technical principles of the present disclosure will fall within the protection scope of the present disclosure.