Fiber grating sensor for measuring soil pressure

Abstract

The utility model discloses a fiber grating sensor for measuring soil pressure, which comprises a shell, the shell comprises a base with a cylindrical structure and an end cover positioned on the surface of the base, and a pressure conduction device and a measuring unit are arranged in the shell; the pressure conduction device comprises a guide pillar fixing seat, a modularized guide pillar sleeve, a guide pillar and a compression spring, one end of the guide pillar is connected with the guide pillar fixing seat, the other end of the guide pillar abuts against the bottom of the base, and the modularized guide pillar sleeve and the compression spring surround the axial side face of the guide pillar; the measuring unit comprises a substrate fixing seat, a modularized temperature compensation substrate, a modularized pressure elastic sheet and a substrate pressing plate, the modularized temperature compensation substrate and the modularized pressure elastic sheet are fixed on the substrate fixing seat through the substrate pressing plate, and one end of the modularized pressure elastic sheet abuts against the tip end of the guide column; the device does not use electric energy in the detection process, belongs to a safe sensor, has strong anti-electromagnetic interference performance, can be used for a long time in a severe environment, is not easy to damage, and has a long measurement distance.

Description

Technical Field

[0001] The utility model belongs to the technical field of pressure sensors, in particular to a fiber grating sensor for measuring soil pressure. Background Art

[0002] Whether in the construction period or the operation period, soil stress monitoring must be carried out to ensure the safe operation of the building. Traditional monitoring mainly relies on manual work, using conventional monitoring technology and traditional electrical sensors to collect data. Not only is the monitoring range small, the efficiency is low, and the operation is cumbersome, but the monitored data is complex and abstract, and its accuracy and real-time performance cannot be guaranteed, making it difficult to meet the requirements of modern construction monitoring. Therefore, soil stress monitoring technology is in urgent need of innovation and should develop from point-to-point to distributed, automated, and high-precision to meet the needs of modern soil monitoring and evaluation.

[0003] For example, Chinese patent CN112230327A discloses "an all-glass packaging device and packaging method for fiber gratings", and the innovatively developed new fiber grating sensor substrate based on this solves the current problems of durability and poor stability of fiber grating sensors. There is also Chinese patent number: 202322637983.7 discloses a substrate-type fiber grating soil pressure sensor, which has the advantages of good stability and durability, and can meet the application in complex environments such as mines and construction. Although the measurement accuracy has been improved, it is limited by the machining accuracy of the outer shell ejector pin, the change of the ejector pin's motion trajectory, and the large degree of freedom of assembly of the sensor substrate base, and the accuracy of batch products cannot be stabilized. In order to continuously and stably improve the monitoring accuracy and minimize the influence of processing accuracy and human factors on the accuracy, it is necessary to propose a new fiber grating sensor for soil pressure measurement from the aspects of improving the conduction accuracy, compressing the conduction gap, and improving the assembly accuracy. Utility Model Content

[0004] The utility model provides a fiber grating sensor for soil pressure measurement, which can solve the problem that traditional monitoring mainly relies on manual labor, uses conventional monitoring technology and traditional electrical sensors to collect data, not only has a small monitoring range, low efficiency, and cumbersome operation, but also the monitored data is complicated and abstract, and its accuracy and real-time performance cannot be guaranteed, making it difficult to meet the requirements of modern construction monitoring.

[0005] To solve the above problems, the technical solutions provided by the present invention are as follows:

[0006] The utility model provides a fiber Bragg grating sensor for measuring soil pressure, comprising a housing (1), wherein the housing (1) comprises a base (101) of a cylindrical structure and an end cover (102) located on the surface of the base (101), and a pressure transmission device (2) and a measuring unit (3) are arranged in the housing (1);

[0007] The pressure transmission device (2) comprises a guide post fixing seat (201), a modular guide post sleeve (202), a guide post (203) and a compression spring (204), wherein one end of the guide post (203) is connected to the guide post fixing seat (201), and the other end is arranged to abut against the bottom of the base (101), and the modular guide post sleeve (202) and the compression spring (204) are arranged around the axial side of the guide post (203); the measuring The unit (3) comprises a substrate fixing seat (301), a modular temperature compensation substrate (302), a modular pressure spring sheet (303) and a substrate pressing plate (304); the modular temperature compensation substrate (302) and the modular pressure spring sheet (303) are fixed on the substrate fixing seat (301) via the substrate pressing plate (304); one end of the modular pressure spring sheet (303) is arranged to be supported against the tip (203-1) of the guide column (203);

[0008] A first boss (101-1) and a second boss (101-2) are arranged oppositely on both sides of the base (101); a first square groove (101-3) is provided on the first boss (101-1); a second square groove (101-4) is provided in the first square groove (101-3); the second square groove (101-4) is communicated with the inner cavity of the base (101); one end of the guide column fixing seat (201) is embedded in the second square groove (101-4) and the first square groove (101-3);

[0009] The second boss (101-2) defines a third groove (101-6), a fourth groove (101-7) is defined in the third groove (101-6), the fourth groove (101-7) is communicated with the inner cavity of the base (101), one end of the substrate fixing seat (301) is embedded in the third groove (101-6) and the fourth groove (101-7); and a waterproof joint (103) is also connected to the outer side of the substrate fixing seat (301).

[0010] According to an optional embodiment of the utility model, the substrate fixing seat (301) is provided with a plurality of second cylindrical countersunk holes (301-1) on the side surface corresponding to the second boss (101-2), and the base (101) is provided with a plurality of first threaded holes (101-5). A plurality of bolts pass through the plurality of second cylindrical countersunk holes (301-1) and the plurality of first threaded holes (101-5) to fix the substrate fixing seat (301) on the second boss (101-2).

[0011] According to an optional embodiment of the utility model, a plurality of third threaded holes (301-2) are provided on the substrate fixing seat (301), and a plurality of bolts sequentially pass through the substrate pressing plate (304), the modular temperature compensation substrate (302), the modular pressure spring (303), the substrate fixing seat (301) and the third threaded holes (301-2) to be fixedly connected.

[0012] According to an optional embodiment of the utility model, a first cylindrical countersunk hole (201-1), a fifth square groove (201-2), a second threaded hole (201-3) and a first through hole (201-4) are provided on one end of the guide column fixing seat (201); the guide column (203) is embedded in the fifth square groove (201-2); the first cylindrical countersunk hole (201-1), the second threaded hole (201-3) and the first through hole (201-4) are used to fix the guide column (203); The modular guide column sleeve (202) is provided with an anisotropic hole (202-1) at a position corresponding to the fifth square groove (201-2); the bottom of the guide column (203) is provided with a hemispherical surface (203-2) and a truncated cone (203-3); the hemispherical surface (203-2) is arranged to abut against the bottom of the base (101); the upper plane of the truncated cone (203-3) contacts the lower end of the compression spring (204), and the upper end of the compression spring (204) contacts the modular guide column sleeve (202).

[0013] Compared with the prior art, the embodiment of the utility model provides a fiber grating sensor for soil pressure measurement, which has the following beneficial effects:

[0014] (1) The guide post fixing seat, substrate fixing seat, modular guide post sleeve, etc. of the present invention are all embedded, which greatly reduces the possibility of accuracy loss due to installation, improves monitoring accuracy and processing efficiency, and avoids human factors affecting the accuracy of monitoring data.

[0015] (2) The utility model uses a compression spring to tightly fit the guide post and the pressure-bearing surface. The guide post performs linear motion in the modular guide post sleeve. The special-shaped hole is precisely processed to have a small gap, thereby avoiding the processing error of the one-piece processed guide post and the disadvantage of not being able to linearly transmit the deformation during deformation. The precision processing effectively reduces the gap error and the relative sliding and vibration between the guide post and the modular elastic substrate during pressure monitoring, which significantly improves the monitoring accuracy. The modular guide post sleeve is a replaceable module for a series of products, which reduces the processing cost.

[0016] (3) The modular temperature compensation substrate is used as a temperature compensation correction while simultaneously measuring the ambient temperature of the installation location, and is not affected by temperature. The modular temperature compensation substrate and modular pressure spring are specially packaged in a solid state glass. The fiber grating and spring are tightly combined, and have the advantages of long life, anti-oxidation, anti-fatigue, and not easy to disengage. They are all replaceable and modular.

[0017] (4) The utility model is suitable for long-term measurement of soil pressure changes of buildings and structures. The outer shell and other parts are made of inorganic metal and inorganic non-metal materials. No electric energy is used in the detection process. It is an intrinsically safe sensor with strong anti-electromagnetic interference performance, can be used for a long time in harsh environments and is not easy to damage. The measurement distance is long, and it can meet the current monitoring requirements in terms of continuity, real-time and measurement sensitivity. After the sensor is processed, the pressure change and temperature change are calibrated and a fitting curve is generated. After installation, the starting wavelength and ambient temperature are recorded. In subsequent measurements, the pressure change can be obtained by substituting the measured value into the fitting formula, and there is no zero drift phenomenon. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 A schematic diagram of the structure of a fiber grating sensor for measuring soil pressure provided in an embodiment of the present application.

[0020] Figure 2 A schematic diagram of the internal structure of a fiber grating sensor for measuring soil pressure provided in an embodiment of the present application.

[0021] Figure 3 A top view of a fiber grating sensor for measuring soil pressure provided in an embodiment of the present application.

[0022] Figure 4 This is a left view of a fiber grating sensor for measuring soil pressure provided in an embodiment of the present application.

[0023] Figure 5 A right view of a fiber grating sensor for measuring soil pressure provided in an embodiment of the present application.

[0024] Figure 6 for Figure 5 Cross-sectional view at AA in the figure.

[0025] Figure 7A schematic diagram of the guide column structure of a fiber grating sensor for soil pressure measurement provided in an embodiment of the present application. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0027] The utility model relates to the field of fiber grating soil pressure sensor detection, and aims to solve the problems in the prior art that the accuracy is limited by the machining accuracy of the outer shell ejector pin, the change of the motion trajectory of the integrated ejector pin cannot be effectively controlled, the ejector pin will tilt and then produce relative slip during the conduction process, the sensor substrate base assembly freedom is too large, and other factors limit the accuracy of batch products.

[0028] like Figure 1 , Figure 2 and Figure 3 As shown, an embodiment of the utility model provides a schematic diagram of the structure of a fiber Bragg grating sensor for measuring soil pressure. A structure of a fiber Bragg grating sensor for measuring soil pressure includes a housing 1, and the housing 1 is made of inorganic metal or inorganic non-metallic material. The housing 1 includes a base 101 of a cylindrical structure and an end cover 102 located on the surface of the base 101, and a pressure transmission device 2 and a measuring unit 3 are arranged in the housing 1.

[0029] The pressure transmission device 2 includes a guide post fixing seat 201, a modular guide post sleeve 202, a guide post 203, and a compression spring 204, wherein one end of the guide post 203 is connected to the guide post fixing seat 201, and the other end is set against the bottom of the base 101, and the modular guide post sleeve 202 and the compression spring 204 are set around the axial side of the guide post 203; the measuring unit 3 includes a substrate fixing seat 301, a modular temperature compensation substrate 302, a modular pressure spring 303 and a substrate pressing plate 304, and the modular temperature compensation substrate 302 and the modular pressure spring 303 are fixed on the substrate fixing seat 301 through the substrate pressing plate 304, and one end of the modular pressure spring 303 is set to support the tip 203-1 of the guide post 203. The substrate fixing seat 301 and the guide post fixing seat 201 are preferably a two-layer square platform structure with a large bottom layer and a small upper layer.

[0030] The pressure transmission device 2 and the measuring unit 3 in this embodiment are both mounted on the housing, the guide column 203 of the pressure transmission unit 2 is suspended on the guide column fixing seat 201, the modular temperature compensation substrate 302 and the modular pressure spring 303 are suspended on the substrate fixing seat 301, when the pressure changes, the pressure-bearing surface drives the guide column 203 to perform precise linear motion in the modular guide column sleeve 202, and the pressure transmission amount is linear and accurate. The compression spring 204 applies a reaction force to the guide column 203 through the guide column 203 cone, keeps the guide column 203 and the measuring pressure-bearing surface of the base 103 tightly connected at all times, and the compression transmission gap greatly reduces the measurement error. The guide column fixing seat 201 and the substrate fixing seat 301 are both embedded installations, which minimizes the influence of processing accuracy and human factors on accuracy.

[0031] like Figure 3 , Figure 4 , Figure 5 and Figure 6 As shown, the first boss 101-1 and the second boss 101-2 are arranged on both sides of the base 101, and the first boss 101-1 and the second boss 101-2 are arranged in parallel in a plane. The first boss 101-1 defines a first square groove 101-3, and the first square groove 101-3 defines a second square groove 101-4, and the second square groove 101-4 is connected with the inner cavity of the base 101; one end of the guide column fixing seat 201 is embedded in the second square groove 101-4 and the first square groove 101-3. Preferably, the upper structure of the guide column fixing seat (201) passes through the second square groove 101-4 and extends to the inner cavity of the base 101.

[0032] The second boss 101-2 defines a third groove 101-6, and a fourth groove 101-7 is defined in the third groove 101-6. The fourth groove 101-7 is connected to the inner cavity of the base 101. One end of the substrate fixing seat 301 is embedded in the third groove 101-6 and the fourth groove 101-7. A waterproof joint 103 is also connected to the outer side of the substrate fixing seat 301. Preferably, the upper structural seam of the substrate fixing seat 301 passes through the fourth groove 101-7 and extends to the inner cavity of the base 101.

[0033] The substrate fixing seat 301 has a plurality of second cylindrical countersunk holes 301-1 on the side surface corresponding to the second boss 101-2, and the base 101 has a plurality of first threaded holes 101-5. A plurality of bolts pass through the plurality of second cylindrical countersunk holes 301-1 and the plurality of first threaded holes 101-5 to fix the substrate fixing seat 301 on the second boss 101-2.

[0034] The substrate fixing seat 301 is provided with a plurality of third threaded holes 301-2, and a plurality of bolts sequentially pass through the substrate pressing plate 304, the modular temperature compensating substrate 302, the modular pressure spring 303, the substrate fixing seat 301 and are fixedly connected with the third threaded holes 301-2. The center line of the modular pressure spring 303, the center line of the substrate fixing seat 301, and the center line of the guide column fixing seat 201 are coplanar with the axis of the base 101. Preferably, a plurality of third threaded holes 301-2 are provided on the side of the upper structure of the substrate fixing seat 301 parallel to the bottom surface of the inner cavity of the base 101, and a plurality of bolts sequentially pass through the tightly fitted substrate pressing plate 304, the modular temperature compensating substrate 302, and the modular pressure spring 303 and are tightly meshed with the third threaded holes 301-2.

[0035] A fourth threaded hole 301-3 is provided at the center of the bottom surface of the substrate fixing seat 301, and the axis of the fourth threaded hole 301-3 is close to the substrate surface; the waterproof connector 103 is engaged with the fourth threaded hole 301-3 to lock and fix the modular temperature compensation substrate 302 and the modular pressure spring 303 near the protective sleeve of the optical fiber.

[0036] like Figure 6 and Figure 7 As shown, a first cylindrical countersunk hole 201-1, a fifth square groove 201-2, a second threaded hole 201-3 and a first through hole 201-4 are provided on one end of the guide column fixing seat 201, and the guide column 203 is embedded in the fifth square groove 201-2; the first cylindrical countersunk hole 201-1, the second threaded hole 201-3 and the first through hole 201-4 are used to fix the guide column 203, and the modular guide column sleeve 202 is provided with an anisotropic hole 202-1 at the position corresponding to the fifth square groove 201-2, and the bottom of the guide column 203 is provided with a hemispherical surface 203-2 and a frustum 203-3, and the hemispherical surface 203-2 is arranged to conflict with the bottom of the base 101; the upper plane of the frustum 203-3 contacts the lower end of the compression spring 204, and the upper end of the compression spring 204 contacts the modular guide column sleeve 202.

[0037] Specifically, a fifth square groove 201-2 is provided on the upper surface of the guide post fixing seat 201 opposite to the ground of the base 101, and the modular guide post sleeve 202 is embedded in the fifth square groove 201-2; a second threaded hole 201-3 is provided on the top surface of the upper surface of the guide post fixing seat 201, which passes through the fifth square groove 201-2; a bolt passes through the second threaded hole 201-3 to lock the modular guide post sleeve 202, and the tip 203-1 of the guide post 203 passes through the special hole 202-1 provided in the modular guide post sleeve 202; a first through hole 201-4 is provided at a corresponding position of the guide post fixing seat above the special hole 202-1, for passing the guide post 203. The special-shaped hole 202-1 of the modular guide post guide sleeve is a large semicircular cross-section, and the intersection of the arc and the chord is rounded.

[0038] The guide column 203 is cylindrical, with a tip 203-1 at the upper end, a straight line in the taper parallel to the boss 101-2, a hemispherical surface 203-2 at the bottom, a frustum 203-3 at the upper part of the hemispherical surface 203-2, an upper plane of the frustum 203-3 contacts the lower end of the compression spring 204, and an upper end of the compression spring 204 contacts the modular guide column sleeve 202, and a cross-section of the guide column at the upper half of the frustum 203-3 is consistent with the shape of the special-shaped hole 202-1, and is precisely fitted with the special-shaped hole 202-1.

[0039] In another embodiment, in order to further increase the precision and improve the processing efficiency, the fifth square groove 201-2, the second threaded hole 201-3, the modular guide column sleeve 202, and the special hole 202-1 may not be opened, and the special holes may be opened directly at the corresponding positions of the guide column fixing seat 201, thereby reducing the processing accessories and improving the processing and assembly efficiency.

[0040] The working principle of the fiber grating sensor for soil pressure measurement of the utility model is as follows: the soil pressure acts on the bottom surface of the base 101, and the center position generates linear lift when the bottom surface of the base 101 is under pressure, and the compression spring 204 squeezes the guide column 203 to fit tightly to the center of the bottom surface, and the modular pressure spring 303 tightly presses the upper end cone of the guide column 203, and the guide column 203 accurately transmits the linear lift to the modular pressure spring 303, driving the modular pressure spring 303 to bend, the modular temperature compensation substrate 302 and the modular pressure spring 303 are special glass solid-state packages, and the fiber grating is tightly combined with the spring, which has the advantages of long life, oxidation resistance, fatigue resistance, and not easy to disengage, and is replaceable and modular, and can distinguish tiny deformations of pm level. The modular temperature compensation substrate 303 is used as a temperature compensation correction while simultaneously measuring the ambient temperature of the installation location, and is not affected by temperature; the substrate is connected to a fiber grating demodulator through an optical fiber, and the demodulator can distinguish the central wavelength changes of the fiber grating sensitive element and the reflected light in the temperature compensation grating, and then calculate the wavelength change of the fiber grating sensitive element and eliminate the influence of temperature on the sensitive element. After the sensor is processed, the pressure change and temperature change are calibrated and a fitting curve is generated. After installation, the starting wavelength and ambient temperature are recorded. Subsequent measurements can be made according to the measured value into the fitting formula to obtain the pressure change, and there is no zero drift phenomenon. The waterproof connector 103 installed on the substrate fixing seat 301 is used to lock and fix the modular temperature compensation substrate 302 and the modular pressure spring 303 near the protective sleeve of the optical fiber; all transmission and measurement components are made of inorganic materials, and have the advantages of anti-electromagnetic interference, super life, and long-term detection.

[0041] In summary, although the present invention has been disclosed as above in terms of preferred embodiments, the above preferred embodiments are not intended to limit the present invention. A person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope defined in the claims.

Claims

1. A fiber Bragg grating sensor for measuring soil pressure, characterized in that: The invention comprises a housing (1), wherein the housing (1) comprises a base (101) of a cylindrical structure and an end cover (102) located on the surface of the base (101), and a pressure transmission device (2) and a measuring unit (3) are arranged in the housing (1); The pressure transmission device (2) comprises a guide post fixing seat (201), a modular guide post sleeve (202), a guide post (203) and a compression spring (204), wherein one end of the guide post (203) is connected to the guide post fixing seat (201), and the other end is arranged to abut against the bottom of the base (101), and the modular guide post sleeve (202) and the compression spring (204) are arranged around the axial side of the guide post (203); the measuring The unit (3) comprises a substrate fixing seat (301), a modular temperature compensation substrate (302), a modular pressure spring sheet (303) and a substrate pressing plate (304); the modular temperature compensation substrate (302) and the modular pressure spring sheet (303) are fixed on the substrate fixing seat (301) via the substrate pressing plate (304); one end of the modular pressure spring sheet (303) is arranged to be supported against the tip (203-1) of the guide column (203); A first boss (101-1) and a second boss (101-2) are arranged oppositely on both sides of the base (101); a first square groove (101-3) is provided on the first boss (101-1); a second square groove (101-4) is provided in the first square groove (101-3); the second square groove (101-4) is communicated with the inner cavity of the base (101); one end of the guide column fixing seat (201) is embedded in the second square groove (101-4) and the first square groove (101-3); The second boss (101-2) defines a third groove (101-6), a fourth groove (101-7) is defined in the third groove (101-6), the fourth groove (101-7) is communicated with the inner cavity of the base (101), one end of the substrate fixing seat (301) is embedded in the third groove (101-6) and the fourth groove (101-7); and a waterproof joint (103) is also connected to the outer side of the substrate fixing seat (301).

2. The fiber grating sensor for measuring soil pressure according to claim 1, characterized in that: The substrate fixing seat (301) is provided with a plurality of second cylindrical countersunk holes (301-1) on the side surface corresponding to the second boss (101-2), the base (101) is provided with a plurality of first threaded holes (101-5), and a plurality of bolts pass through the plurality of second cylindrical countersunk holes (301-1) and the plurality of first threaded holes (101-5) to fix the substrate fixing seat (301) on the second boss (101-2).

3. The fiber grating sensor for measuring soil pressure according to claim 1, characterized in that: The substrate fixing seat (301) is provided with a plurality of third threaded holes (301-2), and a plurality of bolts sequentially pass through the substrate pressing plate (304), the modular temperature compensation substrate (302), the modular pressure spring sheet (303), the substrate fixing seat (301) and are fixedly connected with the third threaded holes (301-2).

4. The fiber grating sensor for soil pressure measurement according to claim 1, characterized in that: A first cylindrical countersunk hole (201-1), a fifth square groove (201-2), a second threaded hole (201-3) and a first through hole (201-4) are provided on one end of the guide column fixing seat (201); the guide column (203) is embedded in the fifth square groove (201-2); the first cylindrical countersunk hole (201-1), the second threaded hole (201-3) and the first through hole (201-4) are used to fix the guide column (203); the modular guide column sleeve (201) 02) An anisotropic hole (202-1) is provided at a position corresponding to the fifth square groove (201-2); a hemispherical surface (203-2) and a truncated cone (203-3) are provided at the bottom of the guide column (203); the hemispherical surface (203-2) is arranged to abut against the bottom of the base (101); the upper plane of the truncated cone (203-3) contacts the lower end of the compression spring (204), and the upper end of the compression spring (204) contacts the modular guide column sleeve (202).

Images