Stretch-resistant and compression-resistant optical fiber sensor and intelligent cable thereof

Abstract

The invention discloses a tensile and compression-resistant optical fiber sensor and an intelligent cable thereof, the optical fiber sensor is composed of an optical fiber and a sheath, and the optical fiber comprises a fiber core, a wrapping layer and a double-layer coating layer; the double-layer coating layer is obtained by photo-curing organic silicon resin; the organic silicon resin comprises branched polysiloxane containing double bonds, POSS (Polyhedral Oligomeric Silsesquioxane), a sulfhydryl compound and a photoinitiator; high-temperature-resistant solvent-free organic silicon resin is adopted as the coating layer, a stainless steel spiral pipe and stainless steel woven mesh reinforcing structure is adopted to give tensile and compression-resistant performance to the optical fiber, the optical fiber is implanted into the cable according to the stone arch bridge principle, and the problem that an optical fiber sensor is damaged due to extrusion force in the cable production process is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of optical fiber sensors, and in particular relates to an anti-tensile and anti-compression optical fiber sensor and an intelligent cable thereof. Background Art

[0002] When the power cable is running, the conductor, insulation layer and metal shielding layer will all produce losses and cause the cable to heat up, so that the working temperature of each part increases. The conductor temperature is an important characteristic value for determining the current carrying capacity of the cable. When the cable is overloaded, the high temperature will affect the insulation performance of the insulation material, cause insulation aging, shorten the service life of the cable, and in severe cases will cause fire and power outages. Therefore, it is necessary to monitor the temperature distribution of each layer of the cable in real time during the operation of the cable. At present, the existing technology uses cable temperature monitoring to achieve online monitoring of current carrying capacity. The main temperature measurement methods include thermocouple method, fiber grating monitoring method, distributed fiber optic monitoring technology, etc. Among them, the thermocouple method is widely used, but this method generally only monitors the local temperature of the cable, and the cable current carrying capacity cannot be fully calculated through data. This method also has certain shortcomings in accuracy and stability; the fiber grating monitoring method is to monitor the cable temperature through the fiber grating sensor pre-buried in the cable body. The stability of this method is improved to a certain extent, but it can only achieve quasi-distributed measurement of cable temperature, and the number of fiber grating sensors will increase the investment cost; distributed fiber optic sensing technology has the advantages of anti-electromagnetic interference and continuous measurement of the temperature of each point along the cable, and has been applied to cable temperature measurement projects to a certain extent. However, due to technical limitations, optical fiber is generally laid on the surface of the cable or the surface of the insulation layer. Its monitoring results are easily affected by the internal and external environment, and it is difficult to accurately calculate the conductor temperature. The existing technology mainly measures the cable skin temperature or the insulation surface temperature to derive the conductor core temperature, and combines the ambient temperature to obtain the real-time current carrying capacity of the cable. The data is too single and cannot accurately reflect the internal temperature of the cable. The main problems of the optical fiber sensor itself are that the optical fiber coating has a small temperature measurement range and poor mechanical strength, which makes it difficult to meet the maximum long-term operating temperature requirement of 90°C for the cable conductor; the optical fiber sensor is subjected to certain tensile and compressive stresses during cable processing and construction, and the optical fiber is easily damaged. Summary of the invention

[0003] In order to overcome the deficiencies of the above-mentioned prior art, the present invention adopts high temperature resistant solvent-free silicone resin as the coating layer, and adopts a stainless steel spiral tube and a stainless steel braided mesh reinforcement structure to give the optical fiber anti-tensile and compressive properties, and implants the optical fiber into the cable according to the stone arch bridge principle, thereby solving the problem of optical fiber sensors being damaged by extrusion force during the cable production process.

[0004] The technical scheme for achieving the purpose of the present invention is as follows: a tensile and compressive resistant optical fiber sensor, consisting of a core, a cladding, a double-layer coating layer and a sheath, wherein the double-layer coating layer is obtained by photocuring an organic silicone resin; the sheath comprises Kevlar fiber, ethylene-tetrafluoroethylene copolymer, a stainless steel spiral tube, and a stainless steel woven mesh; the organic silicone resin comprises a branched polysiloxane containing a double bond, a cage-shaped polysilsesquioxane (POSS) containing a double bond or a thiol group, a thiol compound and a photoinitiator; in the organic silicone resin, the ratio of the amount of thiol substance to the amount of double bond substance is (1.5~2):1; the photoinitiator is 1.5~2.5 wt% of the organic silicone resin; and the POSS is at least one of a thiol-containing POSS and a double-bond-containing POSS.

[0005] It should be noted that when preparing the silicone resin, the process from adding the photoinitiator to the time before curing needs to be carried out in the dark.

[0006] Preferably, the POSS is at least one of octamercaptopropyl-POSS and octavinyl-POSS; the thiol compound is one or more of 1,2-ethanedithiol, 1,3-propanedithiol, 1,4-butanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol and mercapto silicone oil; and the photoinitiator is 2-hydroxy-2-methylphenylacetone.

[0007] More preferably, the POSS is octamercaptopropyl-POSS; and the mercapto compound is mercapto silicone oil.

[0008] More preferably, the ratio of the amount of the mercapto substance in the octamercaptopropyl-POSS to the amount of the branched polysiloxane double bond substance is 1:4.

[0009] Preferably, the branched polysiloxane containing double bonds is obtained by the following steps: Vinyl triethoxysilane, diphenyl dimethoxysilane and hexamethyldisiloxane are added to a reaction kettle, and 8-12 mol / L concentrated hydrochloric acid and deionized water are added dropwise through a constant pressure funnel. After reacting at a temperature of 70-90 °C for 2-4 hours, an activated molecular sieve is added, and the reaction is carried out at a temperature of 110-120 °C for 2-4 hours. After the temperature drops to room temperature, the molecular sieve is filtered out, and washed at least twice with a mixed solution of saturated sodium bicarbonate aqueous solution and ethanol, the oil layer is separated, and vacuum dried to obtain a branched polysiloxane containing double bonds.

[0010] More preferably, the molar ratio of the vinyltriethoxysilane, diphenyldimethoxysilane, hexamethyldisiloxane and deionized water is 1: (0.4-0.5): (0.03-0.05): (2-2.2); the concentrated hydrochloric acid is 2-2.5 wt% of the total mass of the system; and the activated molecular sieve is 24-28 wt% of the total mass of the system.

[0011] Preferably, the preparation method of the tensile and compressive resistant optical fiber sensor is as follows: S1. The optical fiber preform rod is released from the pay-off reel under traction from the furnace, passes through the inner coating cup filled with silicone resin, and after being sized by the mold, a layer of silicone resin adheres to the outside of the fiber core, passes through the ultraviolet curing furnace, and the silicone resin is cured under the action of ultraviolet light to form the first layer of a double-layer coating layer on the surface of the fiber core, and then passes through the outer coating cup filled with silicone resin and passes through the ultraviolet curing furnace to form the second layer of the double-layer coating layer; S2. The optical fiber with double coating obtained in step S1 is wound with Kevlar fiber, placed in an ethylene-tetrafluoroethylene copolymer sleeve, and then wound with a layer of Kevlar fiber after installing a stainless steel spiral tube. Finally, a stainless steel braided mesh is put on the outermost layer of Kevlar material.

[0012] Preferably, the pulling speed in step S1 is 50-80 m / min, the coating temperature is 50-60 °C, the coating pressure is 0.05-0.06 MPa, and the UV intensity is 60-70 mW / cm 2 .

[0013] The present invention also protects an intelligent cable, including an optical fiber sensor, a conductor, a conductor shielding layer, an insulating layer, an insulating shielding layer, a communication optical cable, a filling rope, an isolation sleeve, a steel belt armor and an outer sheath. The optical fiber sensor is the optical fiber sensor prepared as described above; the optical fiber sensor implantation process is to directly implant it into the cable conductor, based on the stone arch bridge principle, using a 6-split structure, consisting of 5 tile-shaped blocks and 1 circular wire core wire, and the optical fiber sensor is implanted in the center of the circular wire core wire.

[0014] The optical fiber sensor is at the center of the conductor, and the inner copper wire is mainly subjected to F N 1. F N 2. F N 3. Equal support force, from the attached figure Figure 4 Analysis shows that:

[0015] The combined force of all forces on the inner copper wire is zero, which solves the problem of the optical fiber sensor being damaged by the squeezing force during the production process.

[0016] Beneficial Effects The present invention has the following beneficial effects: 1. The use of solvent-free silicone resin as the optical fiber coating through photocuring has the advantages of low energy consumption, good film-forming properties, and low volatile organic compound emissions; the use of hyperbranched structure for cross-linking has a high cross-linking density, and the introduction of POSS highly stable cage-like rigid skeleton structure further improves the thermal stability of the coating.

[0017] 2. The stainless steel spiral tube and stainless steel braided mesh reinforcement structure are used to give the optical fiber the properties of tensile and compressive resistance.

[0018] 3. Based on the principle of stone arch bridge, the optical fiber is embedded in the cable, and the combined force of the inner copper wire is zero, which solves the problem of optical fiber sensors being damaged by extrusion during the cable production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the structure of the tensile and compressive resistant optical fiber sensor and its intelligent cable of the present invention; In the figure: 100. optical fiber sensor, 200. conductor, 201. conductor shielding layer, 202. insulating layer, 203. insulating shielding layer, 204. filling rope, 205. isolation sleeve, 206. steel belt armor, 207. outer sheath, 300. communication optical cable; 110. optical fiber, 120. Kevlar fiber, 130. ethylene-tetrafluoroethylene copolymer, 140. stainless steel spiral tube, 150. stainless steel braided mesh; Figure 2 The synthetic route and structural schematic diagram of the branched polysiloxane of the present invention; Figure 3 is the infrared spectra of vinyltriethoxysilane and the branched polysiloxane of the present invention; Figure 4 This is a force analysis diagram of the optical fiber sensor of the present invention in a conductor; Figure 5 This is a temperature curve diagram of the conductor collected by the thermocouple and the temperature collected by the optical fiber sensor at currents of 500A and 600A in Application Example 1 of the present invention. DETAILED DESCRIPTION

[0020] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments 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 creative work are within the scope of protection of the present invention.

[0021] In the examples, the experimental methods used are conventional methods unless otherwise specified, and the materials, reagents, etc. used are all commercially available unless otherwise specified.

[0022] The raw materials and equipment used in the embodiments and comparative examples are described as follows: Vinyltriethoxysilane: product number B604872, purchased from Shanghai Boer Chemical Reagent; Diphenyldimethoxysilane: product number W810220, purchased from Anaiji Chemical; Hexamethyldisiloxane: product number W320004, purchased from Anaiji Chemical; Mercapto silicone oil: viscosity (25°C) 500 mPas, mercapto molar fraction 3%, purchased from Shanghai Koraman Reagents; Phenyl vinyl silicone oil: viscosity (25℃) 1500 mPas, phenyl molar fraction 30%, vinyl molar fraction 3.2%, Shanghai Jiader Chemical Technology Co., Ltd.; 2-Hydroxy-2-methylphenylacetone: photoinitiator 1173, purchased from Hubei Zhenbo Chemical Co., Ltd.; Octamercaptopropyl-POSS: purchased from Jinan Shicheng Silicone Technology Co., Ltd.; OPTIGARD™ 03-6696: available from Dow Chemical.

[0023] Branched polysiloxane (self-made): 1 mol of vinyltriethoxysilane, 0.5 mol of diphenyldimethoxysilane and 0.05 mol of hexamethyldisiloxane were added to a reaction kettle, and 2.4 wt% of 12 mol / L concentrated hydrochloric acid and 2.2 mol of deionized water were added dropwise through a constant pressure funnel. After reacting for 3 h at 90 °C, 26 wt% of activated molecular sieves were added to the system, and the reaction was carried out at 120 °C for 3 h. After the temperature dropped to room temperature, the molecular sieves were filtered out, and washed at least twice with a mixed solution of saturated sodium bicarbonate aqueous solution and ethanol, the oil layer was separated, and vacuum dried to obtain branched polysiloxane.

[0024] Table 1 Silicone resin formula

[0025] After preparing according to the formula in Table 1 above, add the photoinitiator 2-hydroxy-2-methylphenylacetone in a dark place in an amount of 2.0 wt% of the total mass of the silicone resin, stir evenly in a dark place, and then pour it into a coating cup. After vacuum degassing in a dark place, it can be used for optical fiber coating.

[0026] A tensile and compressive resistant optical fiber sensor, the preparation method is as follows: S1. The optical fiber preform rod is pulled out from the furnace at a speed of 80 m / min from the pay-off reel, passed through the inner coating cup filled with silicone resin, the coating temperature is 50~60 ℃, the coating pressure is 0.05~0.06 Mpa, and after the mold is sized, a layer of silicone resin is adhered to the outside of the fiber core. The ultraviolet light intensity is 60~70 mW / cm 2The organic silicon resin is cured under the action of ultraviolet light to form the first layer of the double-layer coating on the surface of the fiber core, and then passes through the outer coating cup filled with organic silicon resin and passes through the ultraviolet curing oven to form the second layer of the double-layer coating; S2. The optical fiber with double coating obtained in step S1 is wound with Kevlar fiber, placed in an ethylene-tetrafluoroethylene copolymer sleeve, and then wound with a layer of Kevlar fiber after installing a stainless steel spiral tube. Finally, a stainless steel braided mesh is put on the outermost layer of Kevlar material.

[0027] Embodiment 1~3 The inner coating cup and the outer coating cup were replaced with silicone resins 1 to 3 in sequence, and Examples 1 to 3 were obtained by the above preparation method.

[0028] Comparative Examples 1 to 3 The inner coating cup and the outer coating cup were replaced with silicone resins 4, 5 and commercially available silicone resin OPTIGARDTM 03-6696, respectively, and comparative examples 1 to 3 were obtained by the above preparation method.

[0029] Comparative Example 4 The difference from Example 3 is that the installation in step S2 is not performed.

[0030] Application Example 1 A smart cable comprises an optical fiber sensor, a conductor, a conductor shielding layer, an insulating layer, an insulating shielding layer, a communication optical cable, a filling rope, an isolation sleeve, a steel belt armor and an outer sheath. The optical fiber sensor is the optical fiber sensor prepared in Example 3. The optical fiber sensor is implanted directly into the cable conductor. According to the principle of a stone arch bridge, a 6-segment structure is adopted, which consists of 5 tile-shaped stock blocks and 1 circular core wire. The optical fiber sensor is implanted in the center of the circular core wire.

[0031] Application Example 2 The difference from Application Example 1 is that the optical fiber sensor is implanted in the outer layer of the cable sheath.

[0032] The following is the test method of the performance parameters involved in the present invention: 1) Tensile force test: Take 3 sections of samples, each section is 50 meters, and use a microcomputer tensile meter to perform tensile tests step by step, with a tensile speed of 100 mm / min, and use an optical power meter to measure the additional loss; 2) High temperature resistance: Place the entire optical fiber sensor plate in an oven and heat it at 250°C for 2 h, then cool it to room temperature and measure the optical fiber attenuation value; 3) Flattening force test: Take three 50-meter samples, test them with a pressure device, and measure the additional loss with an optical power meter (the allowable flattening force requirements for optical fiber sensors are: long-term 3000 N / 10 cm, keep for 5 minutes, additional loss ≤ 0.03 dB; short-term 4000 N / 10 cm, keep for 1 minute, additional loss ≤ 0.1 dB. After the test, the optical fiber sensor should have no visible cracks); 4) Fiber optic sensor temperature measurement reliability test: Using the built-in fiber optic sensor conductor, a set of thermocouples are inserted into the conductor at the same time. The conductor passes through a current booster and a current transformer. The current transformer signal is connected to the console through a junction box. A step current is loaded on the cable with zero initial current. The current is set to 500 A and 600 A for testing.

[0033] 1-3) are the test methods of Examples 1-3 and Comparative Examples 1-4, and 4) is the test method of Application Examples 1-2.

[0034] Table 2 Tensile strength test performance of optical fiber sensor

[0035] Table 3 High temperature resistance performance of optical fiber sensor

[0036] Table 4 Optical fiber sensor flattening force test

[0037] It can be seen from the data in Tables 2 to 4 that the high temperature resistance of the optical fiber mainly depends on the properties of the coating. Examples 1 to 3 have better high temperature resistance. Among Comparative Examples 1 to 3, Comparative Examples 1 to 2 have poor effects. Comparative Example 3 is a commercially available silicone resin, which has a better effect, but not as good as Examples 1 to 3. By comparing the data of Example 3 with Comparative Example 4, it can be seen that the pressure resistance and tensile strength of the optical fiber are mainly provided by the outer sheath.

[0038] The reliability test of temperature measurement by optical fiber sensor shows that the error between the temperature collected by thermocouple and the temperature collected by optical fiber sensor in application example 1 is 0.05~0.1% in 1~15 h; the error between the temperature collected by thermocouple and the temperature collected by optical fiber sensor in application example 2 is 15.2~18.6% in 1~15 h.

[0039] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A tensile and compressive optical fiber sensor, consisting of an optical fiber and a sheath, characterized in that: The optical fiber comprises a core, a cladding, and a double-layer coating layer; the double-layer coating layer is obtained by photocuring an organic silicone resin; the organic silicone resin comprises a branched polysiloxane containing double bonds, POSS, a thiol compound, and a photoinitiator; in the organic silicone resin, the ratio of the amount of thiol substance to the amount of double bond substance is (1.8-2.2):1; the photoinitiator is 1.5-2.5 wt% of the organic silicone resin; and the POSS is at least one of a thiol-containing POSS and a double-bond-containing POSS.

2. The tensile and compressive optical fiber sensor according to claim 1, characterized in that: The sheath comprises Kevlar fiber, ethylene-tetrafluoroethylene copolymer, stainless steel spiral tube and stainless steel braided mesh.

3. The tensile and compressive optical fiber sensor according to claim 1, characterized in that: The branched polysiloxane containing double bonds is obtained by the following steps: Vinyl triethoxysilane, diphenyl dimethoxysilane and hexamethyldisiloxane are added to a reaction kettle, and concentrated hydrochloric acid and deionized water are added through a constant pressure funnel. After reacting at a temperature of 70-90 ° C for 2-4 hours, an activated molecular sieve is added, and the reaction is carried out at a temperature of 110-120 ° C for 2-4 hours. After the temperature drops to room temperature, the molecular sieve is filtered out, and washed at least twice with a mixed solution of saturated sodium bicarbonate aqueous solution and ethanol, the oil layer is separated, and vacuum dried to obtain a branched polysiloxane containing double bonds.

4. The tensile and compressive resistant optical fiber sensor according to claim 1, characterized in that: The POSS is at least one of octamercaptopropyl-POSS and octavinyl-POSS; the thiol compound is one or more of 1,2-ethanedithiol, 1,3-propanedithiol, 1,4-butanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol and mercapto silicone oil; and the photoinitiator is 2-hydroxy-2-methylphenylacetone.

5. The tensile and compressive resistant optical fiber sensor according to claim 3, characterized in that: The molar ratio of the vinyl triethoxysilane, diphenyl dimethoxysilane, hexamethyldisiloxane and deionized water is 1: (0.4-0.5): (0.03-0.05): (2-2.2); the concentration of the concentrated hydrochloric acid is 8-12 mol / L, and the mass is 2-2.5 wt% of the total mass of the system; the activated molecular sieve is 24-28 wt% of the total mass of the system.

6. The tensile and compressive optical fiber sensor according to any one of claims 1 to 5, characterized in that: The preparation method of the tensile and compressive resistant optical fiber sensor is as follows: S1. The optical fiber preform rod is released from the furnace from the pay-off reel under the traction drive, passes through the inner coating cup filled with silicone resin, and after being sized by the mold, a layer of silicone resin adheres to the outside of the fiber core, passes through the ultraviolet curing furnace, and the silicone resin is cured under the action of ultraviolet light to form the first layer of the double-layer coating layer on the surface of the fiber core, and then passes through the outer coating cup filled with silicone resin and passes through the ultraviolet curing furnace to form the second layer of the double-layer coating layer; S2. The optical fiber with double coating obtained in step S1 is wound with Kevlar fiber, placed in an ethylene-tetrafluoroethylene copolymer sleeve, and then wound with a layer of Kevlar fiber after installing a stainless steel spiral tube. Finally, a stainless steel braided mesh is put on the outermost layer of Kevlar material.

7. The tensile and compressive resistant optical fiber sensor according to claim 6, characterized in that: The pulling speed in step S1 is 50-80 m / min, the coating temperature is 50-60 °C, the coating pressure is 0.05-0.06 MPa, and the UV intensity is 60-70 mW / cm 2 .

8. An intelligent cable, comprising an optical fiber sensor, a conductor, a conductor shielding layer, an insulating layer, an insulating shielding layer, a communication optical cable, a filling rope, an isolation sleeve, a steel belt armor and an outer sheath, characterized in that: The optical fiber sensor is the optical fiber sensor described in any one of claims 1 to 5; the optical fiber sensor implantation process is to directly implant it into the cable conductor, based on the stone arch bridge principle, using a 6-split structure, consisting of 5 tile-shaped blocks and 1 circular wire core wire, and the optical fiber sensor is implanted in the center of the circular wire core wire.

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