Optical cable structure with stress temperature self-compensation and humidity sensing functions

Abstract

The utility model discloses an optical cable structure with stress temperature self-compensation and humidity sensing functions, which comprises an optical cable assembly, a steel strand and a protection tube, and the steel strand is wrapped outside the protection tube; the sensing assembly comprises an optical fiber bundle, and the optical fiber bundle is arranged in the protection tube; the optical fiber bundle comprises a humidity-sensitive optical fiber and a non-humidity-sensitive optical fiber. According to the utility model, the humidity-sensitive optical fiber, the non-humidity-sensitive optical fiber and the steel strand are assembled together to form an optical cable structure, a steel wire in the cable is replaced by the optical cable, the humidity-sensitive optical fiber is sensitive to environmental humidity change and is influenced by environmental humidity, temperature and stress change, and the non-humidity-sensitive optical fiber is not sensitive to environmental humidity and is influenced by environmental temperature and stress change. Temperature and stress compensation is carried out on the humidity-sensitive optical fiber by sensing the internal humidity of the cable through the humidity-sensitive optical fiber and sensing the internal temperature and stress disturbance of the cable through the non-humidity-sensitive optical fiber, the sensing precision of the humidity-sensitive optical fiber is improved, and therefore the purpose of monitoring the internal humidity of the cable is achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of cable humidity monitoring, in particular to an optical cable structure with stress temperature self-compensation humidity sensing functions. Background Art

[0002] Among conventional environmental parameters, humidity is the most difficult to measure accurately. This is because humidity itself is affected by environmental factors such as temperature and atmospheric pressure. Currently, there are two main humidity measurement methods: dry-bulb and wet-bulb hygrometry and electronic humidity sensor hygrometry.

[0003] The dry-bulb and wet-bulb humidity measurement method does not age or lose accuracy over long-term use. However, the wet-bulb must be regularly refilled with water and the wet-bulb gauze replaced. This makes maintenance difficult and costly in extreme detection environments, such as bridge cable humidity monitoring and oil exploration. Electronic humidity sensors, due to their unique operating characteristics, experience a decrease in accuracy over time. These methods are not suitable for detecting humidity within cables.

[0004] Stay cables, main cables, and suspenders are key load-bearing components of bridge structures. When exposed to the atmospheric environment for a long time, they are affected by rain, water vapor, or other corrosive gases, which can cause corrosion of cable wires and endanger the safety performance of the bridge. Therefore, it is very necessary to monitor the humidity inside the cables. Currently, the commonly used methods for cable monitoring include visual inspection, ultrasonic testing, robot testing, and fiber optic sensing.

[0005] Manual visual inspection is a commonly used inspection method, but this method is extremely dangerous and inefficient; the interpretation of test results of ultrasonic testing mainly relies on the inspector's personal experience and judgment; robotic inspection clamps the robot on the inclined cable and suspension bridge suspender to detect cable surface damage and internal broken wires. However, the corrosion status inside the cable body and anchor head is a blind spot for robotic inspection.

[0006] The optical fiber sensing detection method can effectively obtain the environmental status inside the cable body, and the maintenance cost is low. However, since humidity measurement is affected by many aspects, many factors need to be considered collaboratively. Therefore, how to use optical fiber sensing technology to achieve accurate humidity measurement is an urgent technical problem that needs to be solved. Based on this, the utility model proposes an optical cable structure with stress-temperature self-compensation humidity sensing function. Utility Model Content

[0007] The purpose of the present utility model is to provide an optical cable structure with stress temperature self-compensation humidity sensing function, so as to solve the problem that the optical fiber sensing detection method proposed in the above background technology can effectively obtain the environmental status inside the cable body and has low maintenance costs. However, since humidity measurement is affected by many aspects, many factors need to be considered in a coordinated manner. Therefore, how to use optical fiber sensing technology to achieve accurate measurement of humidity is an urgent technical problem that needs to be solved.

[0008] To achieve the above-mentioned object, the present invention provides the following technical solution: an optical cable structure with stress temperature self-compensation and humidity sensing function, comprising an optical cable assembly including a steel strand and a protective tube, wherein the steel strand is wrapped around the outside of the protective tube;

[0009] a sensing assembly comprising an optical fiber bundle, wherein the optical fiber bundle is disposed within the protective tube;

[0010] The optical fiber bundle includes moisture-sensitive optical fibers and non-moisture-sensitive optical fibers.

[0011] As a preferred solution of the optical cable structure with stress temperature self-compensation humidity sensing function of the utility model, the moisture-sensitive optical fiber and the non-humidity-sensitive optical fiber are bonded side by side to form a fiber bundle, and the grating points of the moisture-sensitive optical fiber are flush with those of the non-humidity-sensitive optical fiber.

[0012] As a preferred solution of the optical cable structure with stress temperature self-compensation and humidity sensing function of the utility model, the non-humidity-sensitive optical fiber is an acrylic resin optical fiber.

[0013] As a preferred solution of the optical cable structure with stress temperature self-compensation and humidity sensing function of the utility model, a metal braided mesh is further provided between the steel strands and the protective tube, and the metal braided mesh is wrapped around the outside of the protective tube.

[0014] As a preferred solution of the optical cable structure with stress temperature self-compensation and humidity sensing function of the utility model, fiber filaments are further arranged on one side of the optical fiber bundle in the protective tube.

[0015] As a preferred solution of the optical cable structure with stress temperature self-compensation and humidity sensing functions of the utility model, the protective tube is a spiral armored tube.

[0016] As a preferred solution of the optical cable structure with stress temperature self-compensation and humidity sensing function of the utility model, the steel strand is composed of double-layer steel wires twisted together.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] The utility model assembles moisture-sensitive optical fiber and non-humidity-sensitive optical fiber together with steel strands to form an optical cable structure, and replaces one steel wire in the cable with the optical cable. The moisture-sensitive optical fiber is sensitive to changes in ambient humidity and is affected by changes in ambient humidity, temperature and stress, while the non-humidity-sensitive optical fiber is insensitive to ambient humidity and is affected by changes in ambient temperature and stress. The humidity inside the cable is sensed by the moisture-sensitive optical fiber, and the non-humidity-sensitive optical fiber senses the temperature and stress disturbance inside the cable to perform temperature and stress compensation on the moisture-sensitive optical fiber, thereby improving the sensing accuracy of the moisture-sensitive optical fiber, thereby achieving the purpose of monitoring the humidity inside the cable. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a three-dimensional schematic diagram of the utility model;

[0020] Figure 2 It is a cross-sectional schematic diagram of the utility model;

[0021] Figure 3 A three-dimensional schematic diagram of an optical fiber bundle of the present invention;

[0022] Figure 4 It is a cross-sectional schematic diagram of the utility model installed in a cable.

[0023] In the figure: 1. Optical cable assembly; 101. Steel strand; 102. Protective tube; 103. Metal braided mesh; 104. Fiber filament; 2. Sensing assembly; 201. Optical fiber bundle; 201a. Moisture-sensitive optical fiber; 201b. Non-moisture-sensitive optical fiber; 201c. Grating point. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0025] See also Figures 1-4 , an optical cable structure with stress temperature self-compensation humidity sensing function, the optical cable assembly 1, includes a steel strand 101 and a protective tube 102, the steel strand 101 is wrapped around the outside of the protective tube 102;

[0026] The sensing component 2 includes an optical fiber bundle 201 , which is disposed in the protective tube 102 ;

[0027] The optical fiber bundle 201 includes a moisture-sensitive optical fiber 201a and a non-moisture-sensitive optical fiber 201b;

[0028] The steel strand 101 is composed of double-layer steel wires, with the number of steel wires being 12-40.

[0029] In this embodiment, the moisture-sensitive optical fiber 201a and the non-moisture-sensitive optical fiber 201b are bonded side by side to form the optical fiber bundle 201. The grating points 201c of the moisture-sensitive optical fiber 201a and the non-moisture-sensitive optical fiber 201b are flush. The non-moisture-sensitive optical fiber 201b is an acrylic resin optical fiber.

[0030] When implementing it specifically, Figure 3 As shown, a fiber Bragg grating (FBG) demodulation device is used to locate the first grating point in the moisture-sensitive fiber and the non-humidity-sensitive fiber. After the grating points in the two fibers are aligned, glue is applied approximately 3 cm to the left and right of the grating to ensure that the two fibers are subject to the same temperature and stress and are under the same temperature and stress conditions, thus achieving temperature and stress compensation. The fiber Bragg grating spacing of the moisture-sensitive fiber and the non-humidity-sensitive fiber is arranged in a fixed periodic pattern. Therefore, after the position of the first grating point is confirmed, the next grating point is found at the periodic spacing between the gratings and glue is applied in the same manner to complete the bonding between the two fibers.

[0031] It should be noted that humidity-sensitive optical fiber: coated with a special coating, is sensitive to changes in ambient humidity, and is affected by changes in ambient humidity, temperature, and stress. It is the main component for humidity sensing; acrylic resin optical fiber: has no special coating, is insensitive to ambient humidity, and is affected by changes in ambient temperature and stress; humidity-sensitive optical fiber and acrylic resin optical fiber have the same grating period spacing;

[0032] The application principle of humidity-sensitive optical fiber in humidity sensing is mainly based on the response of the humidity-sensitive material to changes in ambient humidity, which causes the central wavelength of the fiber Bragg grating to change. Specifically, the humidity-sensitive material will expand or contract when the humidity changes. This physical change will exert stress on the fiber Bragg grating, causing its reflection wavelength to change. By measuring this wavelength change, the relative humidity in the cable can be accurately monitored.

[0033] The application principle of acrylic resin optical fiber in sensing temperature and stress mainly relies on its material properties and optical effects. The optical fiber with acrylic resin coating uses its thermo-optical coefficient to sense temperature. When the temperature changes, the refractive index of the acrylic resin coated optical fiber will change. This change in refractive index causes the wavelength of the fiber Bragg grating to change, thereby achieving highly sensitive temperature measurement. Regarding stress sensing, when the external stress changes on the acrylic resin optical fiber, it causes the refractive index of the optical fiber to change, thereby causing the wavelength of the fiber Bragg grating to change, realizing the sensing of stress.

[0034] The method of using acrylic resin optical fiber to perform temperature and stress self-compensation on moisture-sensitive optical fiber can effectively deduct the wavelength change caused by temperature and stress changes, thereby improving sensing accuracy;

[0035] like Figure 4As shown, the humidity optical cable can be laid throughout the cable to perform online monitoring of humidity changes in the cable. During installation, the finished humidity optical cable will replace a steel wire in the cable, and will be installed in the cable body together with the steel wire bundle through processes such as wire arrangement, wrapping, and twisting. The shaded part in the figure is the humidity optical cable.

[0036] In this embodiment, a metal braided mesh 103 is further provided between the steel strand 101 and the protection tube 102 , and the metal braided mesh 103 is wrapped around the outside of the protection tube 102 ;

[0037] A fiber filament 104 is further provided on one side of the optical fiber bundle 201 in the protection tube 102;

[0038] Among them, the protective tube 102 is a spiral armored tube, which is made of stainless steel and has extremely strong compressive resistance, and protects the optical fiber bundle 201. The metal braided mesh 103 is made of stainless steel. The metal braided mesh 103 is wrapped around the outside of the spiral armored tube to further improve the mechanical strength of the spiral armored tube and prevent the spiral armored tube from being pulled. The fiber filament 104 is made of Kevlar aramid fiber material. The fiber filament 104 serves as a reinforcing element in the optical cable, which can buffer external stress and protect the optical fiber.

[0039] In summary, the utility model uses moisture-sensitive optical fiber to sense the humidity inside the cable, and non-humidity-sensitive optical fiber to sense the temperature and stress disturbance inside the cable to compensate for the temperature and stress of the moisture-sensitive optical fiber, thereby improving the sensing accuracy of the moisture-sensitive optical fiber and achieving the purpose of monitoring the humidity inside the cable.

[0040] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the present invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be encompassed within the present invention. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

Claims

1. An optical cable structure with stress, temperature self-compensation and humidity sensing functions, characterized by: include, An optical cable assembly (1) comprises a steel strand (101) and a protective tube (102), wherein the steel strand (101) is wrapped around the outside of the protective tube (102); A sensing component (2) comprising an optical fiber bundle (201), wherein the optical fiber bundle (201) is arranged in the protective tube (102); The optical fiber bundle (201) comprises a moisture-sensitive optical fiber (201a) and a non-moisture-sensitive optical fiber (201b).

2. The optical cable structure with stress temperature self-compensation and humidity sensing function according to claim 1, characterized in that: The moisture-sensitive optical fiber (201a) and the non-moisture-sensitive optical fiber (201b) are bonded side by side to form an optical fiber bundle (201), and the grating points (201c) of the moisture-sensitive optical fiber (201a) and the non-moisture-sensitive optical fiber (201b) are flush.

3. The optical cable structure with stress temperature self-compensation and humidity sensing function according to claim 2, characterized in that: The non-humidity-sensitive optical fiber (201b) is an acrylic resin optical fiber.

4. The optical cable structure with stress temperature self-compensation and humidity sensing function according to claim 1 or 3, characterized in that: A metal braided mesh (103) is further provided between the steel strand (101) and the protective tube (102), and the metal braided mesh (103) is wrapped around the outside of the protective tube (102).

5. The optical cable structure with stress temperature self-compensation and humidity sensing function according to claim 4, characterized in that: A fiber filament (104) is further provided in the protective tube (102) on one side of the optical fiber bundle (201).

6. The optical cable structure with stress temperature self-compensation and humidity sensing function according to claim 5, characterized in that: The protective tube (102) is a spiral armored tube.

7. The optical cable structure with stress temperature self-compensation and humidity sensing function according to claim 1 or 6, characterized in that: The steel strand (101) is composed of double-layer steel wires twisted together.

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