Fiber grating sensor

Abstract

The utility model discloses a fiber grating sensor, relating to the sensor technology field, the fiber grating sensor comprises an optical fiber, a housing and a clamp, the optical fiber is in communication connection with an external demodulator, and the optical fiber is provided with a grating; the shell comprises at least one section of rigid part and at least one section of flexible part which are connected with each other, the rigidity of the flexible part is smaller than that of the rigid part, the interiors of the rigid part and the flexible part are both provided with accommodating channels which are communicated with each other, the optical fiber penetrates through the accommodating channels, and the two end parts of the optical fiber are fixedly connected with the shell; the clamps are arranged at the two ends of the shell so as to fix the shell to a target piece, and when the two ends of the shell are synchronously stretched or compressed along with the target piece, the grating generates stretching deformation or compression deformation. According to the technical scheme provided by the utility model, the problem that an existing sensor shell is easy to break due to multiple times of stretching and compression is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of sensors, and particularly relates to a fiber Bragg grating sensor. Background Art

[0002] Due to the excellent physical, chemical, mechanical and transmission properties of optical fibers, fiber optic sensors have the characteristics of good electrical insulation, fast response speed, large dynamic range, long transmission distance, corrosion resistance, low cost, etc. The central wavelength of the fiber Bragg grating can be directly modulated by strain and has a good linear response, making it an ideal strain measurement element. At present, fiber optic sensors are also increasingly widely used in military, scientific research, industrial, commercial, medical and other fields.

[0003] Since the core diameter of the bare fiber Bragg grating is very small, extremely fragile and has poor shear resistance, it is easily damaged and cannot be directly used in engineering. Therefore, a housing is usually provided outside the optical fiber, and the housing follows the optical fiber to stretch or compress synchronously to achieve the sensing function. However, after long-term stretching or compression deformation of the housing, it is easy to break, shortening the service life. Summary of the Utility Model

[0004] The main purpose of the utility model is to propose a fiber Bragg grating sensor, aiming to solve the problem that the existing sensor housing is prone to breakage due to multiple stretching and compression.

[0005] To achieve the above purpose, the fiber Bragg grating sensor proposed by the utility model includes:

[0006] An optical fiber, communicatively connected to an external demodulator, and a grating is provided on the optical fiber;

[0007] A housing, including at least one rigid part and at least one flexible part connected to each other, the stiffness of the flexible part is less than that of the rigid part, and a communicating accommodation channel is provided inside both the rigid part and the flexible part. The optical fiber is disposed through the accommodation channel, and both ends of the optical fiber are fixedly connected to the housing; and

[0008] A fixture, disposed at both ends of the housing to fix the housing on a target object, and when both ends of the housing stretch or compress synchronously with the target object, the grating generates tensile deformation or compressive deformation.

[0009] In an embodiment, the flexible part includes a plurality of connected sub-sections, the flexible part has an unfolded state and a folded state, and the flexible part is in the folded state when both ends of the housing are compressed towards each other, and the flexible part is in the unfolded state when both ends of the housing are stretched away from each other.

[0010] In one embodiment, a plurality of the rigid parts and a plurality of the flexible parts are provided, and the rigid parts and the flexible parts are arranged alternately.

[0011] In one embodiment, both ends of the housing are the rigid parts, and a clamping groove is provided at the end of the housing. The clamping groove is provided on a side of the housing facing away from the target piece, and the fixture is detachably mounted on the clamping groove.

[0012] In one embodiment, the fiber Bragg grating sensor further includes clamping members. Two clamping members are spaced apart in the accommodation channel. Through holes for the fiber to pass through are provided inside both of the two clamping members, and the grating is located between the two clamping members.

[0013] In one embodiment, each clamping member includes a pressing section for pressing the fiber and a fixing section connected to the pressing section. The fixing section is fixedly connected to the housing. The through hole penetrates through the inside of the pressing section and the fixing section. The fixing sections of the two clamping members face each other and there is a gap between them, and the grating is provided on a portion of the fiber located between the pressing sections of the two clamping members.

[0014] In one embodiment, a limiting block is provided on any one of the fixing sections of the two clamping members. The limiting block is located between the two fixing sections so that the two fixing sections do not come into contact.

[0015] In one embodiment, the fiber Bragg grating sensor further includes a protective tube. The protective tube is provided in the accommodation channel and at the end of the housing, and the fiber is fixedly provided inside the protective tube.

[0016] In one embodiment, the housing is of a prism structure, and a support protrusion is provided on the housing. The support protrusion is provided on a side of the housing facing the target piece for abutting against the target piece.

[0017] In one embodiment, the support protrusion includes a plurality of transverse convex portions and a plurality of vertical convex portions, and the transverse convex portions and the vertical convex portions are arranged crosswise to form a net-shaped support structure.

[0018] In the technical solution of the present utility model, during detection, only the two ends of the fiber Bragg grating sensor housing need to be clamped to the surface of the target component to be monitored for displacement by means of a fixture, and the peripheral surface of the housing is kept in close contact with the surface of the target component. When the target component undergoes tensile deformation due to being pulled outward from both ends or compressive deformation due to being pressed from both ends towards the middle, under the action of the fixture, the housing of the sensor will undergo tensile deformation or compressive deformation together with the target component, causing the two ends of the housing to stretch outward or compress inward. At this time, the grating fixed inside the housing will undergo tensile deformation or compressive deformation, causing the value measured on the demodulator connected to the optical fiber to change, realizing the sensing function of the fiber Bragg grating sensor. In this solution, a flexible part is provided on the housing, and the stiffness of the flexible part is less than that of the rigid part. The setting of the flexible part makes the deformation at the corresponding position where the grating is arranged on the housing more obvious, and it is not easy to deform after multiple tensile and compressive deformations, and the service life of the sensor is longer. Brief Description of the Drawings

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0020] Figure 1 Structural schematic diagram of an embodiment of the fiber Bragg grating sensor provided by the present utility model;

[0021] Figure 2 Structural schematic diagram of the housing in an embodiment of the fiber Bragg grating sensor provided by the present utility model;

[0022] Figure 3 Structural schematic diagram of the fixture clamping and fixing the housing and the target component in another embodiment of the fiber Bragg grating sensor provided by the present utility model;

[0023] Figure 4 Structural schematic diagram of the clamping member in another embodiment of the fiber Bragg grating sensor provided by the present utility model;

[0024] Figure 5 Structural schematic diagram of the bottom of the housing in yet another embodiment of the fiber Bragg grating sensor provided by the present utility model.

[0025] Explanation of the reference numerals in the drawings:

[0026] 100. Fiber Bragg grating sensor; 1. Optical fiber; 2. Housing; 21. Rigid part; 211. Clamping groove; 212. Support protrusion; 2121. Lateral protrusion; 2122. Vertical protrusion; 22. Flexible part; 221. Sub - segment; 3. Fixture; 4. Clamping member; 40. Through - hole; 41. Pressing section; 42. Fixed section; 43. Limit block; 5. Protective tube; 200. Target part.

[0027] The realization of the purpose, functional characteristics and advantages of the present utility model will be further described with reference to the embodiments and the accompanying drawings. Specific embodiments

[0028] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.

[0029] It should be noted that if there are directional indications (such as up, down, left, right, front, back...) involved in the embodiments of the present utility model, the directional indications are only used to explain the relative position relationship and movement conditions between components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0030] In addition, if there are descriptions such as "first", "second", etc. involved in the embodiments of the present utility model, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first", "second" may explicitly or implicitly include at least one such feature. In addition, if "and / or" or "and / or" appears throughout the text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or the solution where A and B are satisfied simultaneously. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present utility model.

[0031] Since the core diameter of the bare fiber Bragg grating is very small, extremely fragile, and has poor shear resistance, it is easily damaged and cannot be directly used in engineering. Therefore, usually an outer shell is provided outside the optical fiber, and the sensing function is realized by the outer shell stretching or compressing synchronously with the optical fiber. However, after long - term stretching or compressing deformation, the outer shell is prone to fracture, shortening the service life.

[0032] The present utility model provides an optical fiber grating sensor, which can be applied to rails or other occasions where stress or deformation needs to be measured.

[0033] Please refer to Figure 1 and Figure 3 In an embodiment of the present utility model, the optical fiber grating sensor 100 includes:

[0034] An optical fiber 1, which is communicatively connected to an external demodulator, and a grating is provided on the optical fiber 1;

[0035] A housing 2, including at least one rigid part 21 and at least one flexible part 22 connected to each other. The stiffness of the flexible part 22 is less than that of the rigid part 21, and accommodating channels that communicate with each other are provided inside both the rigid part 21 and the flexible part 22. The optical fiber 1 is disposed through the accommodating channels, and both ends of the optical fiber 1 are fixedly connected to the housing 2; and

[0036] A fixture 3, which is disposed at both ends of the housing 2 to fix the housing 2 on the target member 200. When both ends of the housing 2 are stretched or compressed synchronously with the target member 200, the grating generates tensile deformation or compressive deformation.

[0037] In the technical solution of the present utility model, during detection, only the two ends of the housing 2 of the optical fiber grating sensor 100 need to be clamped on the surface of the target member 200 whose displacement needs to be monitored through the fixture 3, and the peripheral surface of the housing 2 is kept closely attached to the surface of the target member 200. When the target member 200 undergoes tensile deformation when pulled outward from both ends or undergoes compressive deformation when pressed from both ends to the middle, under the action of the fixture 3, the housing 2 of the sensor will undergo tensile deformation or compressive deformation together with the target member 200, causing the two ends of the housing 2 to stretch outward or compress inward. At this time, the grating fixed inside the housing 2 will generate tensile deformation or compressive deformation, causing the value measured on the demodulator connected to the optical fiber 1 to change, realizing the sensing function of the optical fiber grating sensor 100. In this solution, the flexible part 22 is provided on the housing 2, and the stiffness of the flexible part 22 is less than that of the rigid part 21. The setting of the flexible part 22 makes the deformation at the corresponding position where the grating is provided on the housing 2 more obvious, and it is not easy to deform after multiple tensile and compressive deformations, and the service life of the sensor is longer.

[0038] Specifically, the flexible part 22 can be made of materials such as ethylene-propylene rubber or polyurethane elastomer. When the outer shell 2 undergoes tensile deformation or compressive deformation together with the target part 200, the flexible part 22 will produce obvious corresponding deformation. The rigid part 21 can be made of lightweight materials such as plastic or metal alloy. Due to the relatively large stiffness of the rigid part 21, the outer shell 2 has a certain strength and is not easily squeezed and deformed during the clamping process by the clamp 3. It should be noted that there is no specific limitation on the proportion of the flexible part 22 and the rigid part 21 in the outer shell 2 respectively. As long as there is a part of the flexible part 22 provided, the outer shell 2 can still maintain good shell integrity after being stretched and compressed frequently for many times and will not be easily damaged. In addition, the outer shell 2 can be a cylinder or a quadrangular prism, as long as it is ensured that there is a cylindrical hollow part inside the outer shell 2 to place the optical fiber 1. The accommodation channel inside the outer shell 2 can be cylindrical or other shapes adapted to the shape of the optical fiber 1.

[0039] In an embodiment of the present invention, please refer to Figure 2 , the flexible part 22 includes a plurality of connected sub-sections 221. The flexible part 22 has an unfolded state and a folded state. When the two ends of the outer shell 2 are compressed towards each other, the flexible part 22 is in the folded state. When the two ends of the outer shell 2 are stretched away from each other, the flexible part 22 is in the unfolded state. The multi-sub-section 221 structure of the flexible part 22 enables the flexible part 22 to fold or unfold better, effectively disperses and absorbs external forces, increases the stress points of deformation, enables it to better adapt to different degrees of stretching and compression, reduces the fatigue damage of the optical fiber 1 grating during repeated stretching and compression, and extends the service life of the sensor.

[0040] In an embodiment of the present invention, please refer to Figure 2 , there are a plurality of rigid parts 21 and flexible parts 22, and the rigid parts 21 and the flexible parts 22 are arranged alternately. The rigid part 21 can provide a firm support point for the flexible part 22, making it not easily worn during long-term use. At the same time, the flexible part 22 also reduces the possible fatigue damage to the rigid part 21. The two are arranged alternately, enhancing the structural stability of the entire sensor, enabling it to maintain the stability of shape and position when subjected to external forces. Moreover, since there are a plurality of flexible parts 22, when the sensor is in a non-working state, a part of the flexible part 22 can be compressed, thereby reducing the occupied volume of the entire outer shell 2.

[0041] In an embodiment of the present invention, please refer to Figure 2, both ends of the housing 2 are rigid parts 21, and the ends of the housing 2 are provided with a clamping groove 211, the clamping groove 211 is provided on the side of the housing 2 away from the target part 200, and the clamp 3 is detachably mounted on the clamping groove 211. Since the clamp 3 needs to be clamped on the housing 2, the two ends of the housing 2 are preferably rigid parts 21, and the rigid part 21 is provided with a clamping groove 211. The design of the clamping groove 211 provides a stable fixing point, which helps to evenly transfer the externally applied force to the housing 2, reduces stress concentration, and ensures that the sensor is firmly installed on the target part 200 and is not easy to shift. There is no specific limitation on the shape of the clamping groove 211, for example, it can be a square groove or a circular groove, etc., as long as it is a shape that matches the clamping end of the clamp 3.

[0042] In the embodiments of the present invention, please refer to Figure 4 The fiber Bragg grating sensor 100 further includes a clamping member 4, two of which are arranged at intervals in the accommodating channel, and the inside of the two clamping members 4 is provided with a through hole 40 for the optical fiber 1 to pass through, and the grating is located between the two clamping members 4. By arranging two clamping members 4 in the accommodating channel, the grating is accurately positioned between the two clamping members 4, thereby improving the accuracy of the measurement. Since the grating is fixed between the two clamping members 4, any tensile or compressive deformation will directly act on the grating, thereby improving the sensitivity of the sensor. In this embodiment, the shape of the clamping member 4 is not specifically limited, for example, it can be two clamping plates arranged opposite to each other, and the fixing effect of the housing 2 on the grating can be further increased through the effect of the clamping plates. In specific implementation, since the part of the optical fiber 1 in the pressing part of the clamping member 4 is pressed, when the two clamping members 4 move relative to each other, the grating on the optical fiber 1 located between the two clamping members 4 will be tensilely deformed or compressed, so that the value measured on the demodulator connected to the optical fiber 1 changes, thereby realizing the sensing function of the fiber Bragg grating sensor 100.

[0043] In the embodiments of the present invention, please refer to Figure 4, the clamping member 4 includes a pressing section 41 for pressing the optical fiber 1 and a fixing section 42 connected to the pressing section 41. The fixing section 42 is fixedly connected to the housing 2. A through hole 40 runs through the interior of the pressing section 41 and the fixing section 42. The fixing sections 42 of the two clamping members 4 are arranged facing each other and there is a gap between them. A grating is provided on the portion of the optical fiber 1 located between the pressing sections 41 of the two clamping members 4. The pressing section 41 of the clamping member 4 can effectively press the optical fiber 1, ensuring that the grating remains stable during measurement and is not affected by vibration or displacement. The fixed connection between the fixing section 42 and the housing 2 provides an additional protective layer for the grating, reducing potential damage to the grating from external factors. The design of the through hole 40 enables the optical fiber 1 to be precisely threaded through the clamping member 4, ensuring the correct position of the grating in the sensor. The pressing portion may include a screw and a threaded tube sleeved on the outer periphery of the screw. The screw has a through hole 40 for the optical fiber 1 to pass through, and the threaded tube is threadedly connected to the screw, so that the screw is uniformly pressed by the threaded tube in its circumferential direction, and thus the optical fiber 1 in the through hole 40 of the screw is pressed by the screw.

[0044] It is worth mentioning that in this solution, the tensile deformation and compressive deformation of the portion of the optical fiber 1 with the grating can bring about a change in the tightness of this portion of the optical fiber 1. In practical applications, the optical fiber 1 located between the two clamping members 4 maintains a slightly taut state under normal conditions. When the two ends of the housing 2 are stretched outwards, the tightness of this portion of the optical fiber 1 is higher. When the two ends of the housing 2 are compressed inwards, this portion of the optical fiber 1 will become slack. Both the increased tightness and the increased slackness of the optical fiber 1 can be reflected on the demodulator connected to the optical fiber 1, and the staff can measure the strain and deformation of the target part 200.

[0045] In an embodiment of the present utility model, please refer to Figure 4 , a limiting block 43 is provided on any one of the fixing sections 42 of the two clamping members 4. The limiting block 43 is located between the two fixing sections 42 so that the two fixing sections 42 do not come into contact. In this way, there is always a certain gap between the end faces of the fixing sections 42 of the two clamping members 4, preventing the end face of one clamping member 4 and the end face of the other clamping member 4 from coming into contact with each other due to the proximity of the distance when the two ends of the housing 2 undergo compressive deformation, thus affecting the detection result. There is no specific limitation on the structure of the limiting block 43. For example, it can be a square convex block or other structures with a blocking function, as long as it can play the role of isolating the fixing sections 42 between the two clamping members 4. Of course, in other embodiments, a plugging groove and a plugging head can be respectively provided on the two fixing sections 42, and the cooperation of the plugging groove and the plugging head enables the two clamping members 4 to be close to each other but not come into contact.

[0046] In an embodiment of the present utility model, please refer to Figure 1, the fiber grating sensor 100 further includes a protective tube 5. The protective tube 5 is disposed in the accommodation channel and at the end of the outer shell 2, and the optical fiber 1 is fixedly disposed inside the protective tube 5. The part of the optical fiber 1 passing through the outer shell 2 is prone to being scratched by the edge of the outer shell 2 when the rigid part 21 deforms. To avoid this situation, protective tube through holes 40 can be provided at both ends of the outer shell 2, and the protective tube 5 is provided in the protective tube through holes 40. The protective tube 5 can be threadedly connected to the protective tube through holes 40, and soft materials such as rubber can be provided on the inner wall surface of the protective tube through holes 40 to protect the optical fiber 1.

[0047] In an embodiment of the present invention, please refer to Figure 2 and Figure 5 , the outer shell 2 is a prism structure, and the outer shell 2 is provided with a support protrusion 212. The support protrusion 212 is disposed on the side of the outer shell 2 facing the target member 200 for abutting against the target member 200. The support protrusion 212 is used to fit on the surface of the target member 200 to reduce the contact area between the surface of the outer shell 2 and the surface of the target member 200, so as to reduce the frictional force generated by the movement of the outer shell 2 when the outer shell 2 deforms. It should be noted that the two ends of the outer shell 2 can also be pasted on the surface of the target member 200 by using an adhesive, as long as it can be ensured that the two ends of the outer shell 2 move synchronously with the target member 200.

[0048] In an embodiment of the present invention, please refer to Figure 5 , the support protrusion 212 includes a plurality of transverse protrusions 2121 and a plurality of vertical protrusions 2122, and the transverse protrusions 2121 and the vertical protrusions 2122 are arranged crosswise to form a net-shaped support structure. The crosswise arrangement of the transverse protrusions 2121 and the vertical protrusions 2122 forms a stable net structure, which helps to evenly distribute the sensor weight and external acting forces to the surface of the target member 200, reduce local pressure concentration, and protect the target member 200 from damage.

[0049] The above is only an exemplary embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structural transformation made under the technical concept of the present invention by using the content of the specification and drawings of the present invention, or directly / indirectly applied in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. An optical fiber grating sensor, characterized in that, The fiber Bragg grating sensor includes: an optical fiber communicatively connected to an external demodulator, and a grating is provided on the optical fiber; a housing including at least one rigid portion and at least one flexible portion connected to each other, the stiffness of the flexible portion being less than that of the rigid portion, and accommodating channels communicating with each other are provided inside both the rigid portion and the flexible portion, the optical fiber is disposed through the accommodating channels, and both ends of the optical fiber are fixedly connected to the housing; and clamps provided at both ends of the housing to fix the housing to a target member, and when both ends of the housing synchronously stretch or compress following the target member, the grating generates a tensile deformation or a compressive deformation.

2. The fiber Bragg grating sensor according to claim 1, wherein The flexible portion includes a plurality of connected sub-sections, the flexible portion has an unfolded state and a folded state, and the flexible portion is in the folded state when both ends of the housing are compressed towards each other, and the flexible portion is in the unfolded state when both ends of the housing are stretched away from each other.

3. The fiber Bragg grating sensor according to claim 2, wherein A plurality of the rigid portions and a plurality of the flexible portions are provided, and the rigid portions and the flexible portions are alternately arranged.

4. The fiber Bragg grating sensor according to claim 1, characterized in that, Both ends of the housing are the rigid portions, and a clamping groove is provided at the end of the housing, the clamping groove is provided on a side of the housing facing away from the target member, and the clamp is detachably mounted on the clamping groove.

5. The fiber Bragg grating sensor according to claim 1, wherein The fiber Bragg grating sensor further includes clamping members, two clamping members are spaced apart in the accommodating channel, through holes for the optical fiber to pass through are provided inside both of the two clamping members, and the grating is located between the two clamping members.

6. The fiber Bragg grating sensor according to claim 5, wherein, The clamping member includes a pressing section for pressing the optical fiber and a fixing section connected to the pressing section, the fixing section is fixedly connected to the housing, the through hole penetrates through the inside of the pressing section and the fixing section, the fixing sections of the two clamping members are arranged facing each other and there is a gap between them, and the grating is provided on a portion of the optical fiber located between the pressing sections of the two clamping members.

7. The fiber Bragg grating sensor according to claim 6, wherein A limiting block is provided on any one of the fixing sections of the two clamping members, and the limiting block is located between the two fixing sections so that the two fixing sections do not come into contact.

8. The fiber Bragg grating sensor according to claim 1, characterized in that, The fiber Bragg grating sensor further includes a protective tube, the protective tube is disposed in the accommodating channel and at the end of the housing, and the optical fiber is fixedly disposed inside the protective tube.

9. The fiber Bragg grating sensor according to any one of claims 1 to 8, characterized in that The housing is a prism structure, and support protrusions are provided on the housing on a side facing the target member for abutting against the target member.

10. The fiber Bragg grating sensor according to claim 9, wherein, The support protrusions include a plurality of transverse protrusions and a plurality of vertical protrusions, and the transverse protrusions and the vertical protrusions are arranged crosswise to form a net-shaped support structure.

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