Grating displacement sensor

Abstract

The utility model discloses a grating displacement sensor, which comprises a packaging shell and a packaging cover, one side of the packaging shell is provided with the packaging cover, the inner wall of the packaging shell is provided with a strain gauge, the joint of the strain gauge and the packaging shell is provided with a strain gauge fixer, and the surface of the strain gauge is fixedly provided with a displacement grating. One side of the displacement grating is provided with the temperature compensation grating, one side of the strain gauge is connected with the spring connector, the other side of the spring connector is provided with the extension spring, the other side of the extension spring is provided with the pull rod, the outer side of the extension spring and the outer side of the pull rod are provided with the packaging shell sleeve, and the two sides of the packaging shell are symmetrically provided with through holes. A whole optical fiber penetrates through the packaging shell and the through hole; by simplifying the structure and optimizing the material selection, the production cost is reduced, the number of sensor assemblies is reduced, and the assembly is more convenient and faster; and a strain gauge type structure is adopted, so that the stability and the reliability of the sensor are enhanced.

Description

Technical Field

[0001] The utility model relates to the technical field of structural safety monitoring and the technical field of optical fiber grating, in particular to a grating displacement sensor. Background Art

[0002] With the development of science and technology, the demand for high-precision measurement of physical quantities such as displacement and strain is growing. Among the many measurement technologies, fiber optic sensors have attracted widespread attention due to their advantages such as small size, light weight, strong anti-electromagnetic interference ability, high sensitivity, and passive sensing. Among them, FBG, as an important fiber optic sensing element, has been widely used in structural health monitoring systems in many fields such as bridges, buildings, aerospace, etc.; most traditional displacement measurement methods use inductive or resistive sensors, but these sensors are easily affected by electromagnetic interference and have poor stability in harsh environments. In contrast, FBG-based displacement sensors can provide more reliable data and can work in complex geological environments.

[0003] At present, the existing Chinese patent with publication number CN216178859U discloses a grating displacement sensor, including: a shell, fixed heads located at the left and right ends of the shell respectively, a fixed block located at one side of the shell, a reading head and a grating scale located inside the shell, a strip hole is opened on the side facing the shell and the fixed block, a groove is arranged between the top of the strip hole and the top of the shell for a baffle to be embedded and installed, the fixed block is fixedly connected to the reading head through a bolt passing through the strip hole, a recess is arranged on the side of the reading head opposite to the strip hole for one end of the grating scale to extend into, a fitting block is arranged at the connection between the fixed block and the reading head, the fitting block is fitted and connected with fitting columns symmetrically distributed on the upper and lower sides of the strip hole, and card blocks are respectively installed at the middle ends of the top and bottom of the reading head, and the card blocks are embedded in the card grooves opened on the upper and lower inner walls of the shell. The utility model ensures the stability of the shell during movement, thereby ensuring the measurement accuracy of the grating ruler; although the device solves the above-mentioned shortcomings, the device has high cost, complex structure, inconvenient installation and debugging, and the accuracy and stability need to be improved. It is sensitive to ambient temperature and requires additional temperature compensation measures. In view of the above problems, a grating displacement sensor is provided herein. Utility Model Content

[0004] The technical problem to be solved by the utility model is to overcome the problems of the existing devices, such as high cost, complex structure, inconvenient installation and debugging, need to improve accuracy and stability, sensitivity to ambient temperature, and need for additional temperature compensation measures, and to provide a new grating displacement sensor with low cost, simple structure, high accuracy and strong environmental adaptability.

[0005] To achieve the above object, the present utility model adopts the following technical solution: A grating displacement sensor includes a packaging housing and a packaging cover. One side of the packaging housing is provided with the packaging cover. The inner wall of the packaging housing is provided with a strain gauge. A strain gauge holder is provided at the connection between the strain gauge and the packaging housing. A displacement grating is fixedly provided on the surface of the strain gauge. A temperature compensation grating is provided on one side of the displacement grating. One side of the strain gauge is connected to a spring connector. A tension spring is provided on the other side of the spring connector. A pull rod is provided on the other side of the tension spring. A packaging housing sleeve is provided outside the tension spring and the pull rod. Through holes are symmetrically provided on both sides of the packaging housing. A whole optical fiber penetrates through the packaging housing and the through holes.

[0006] As a further description of the above technical solution:

[0007] The spring connector penetrates through the packaging cover and is connected to the tension spring.

[0008] As a further description of the above technical solution:

[0009] The packaging cover is fixedly connected to the packaging housing to form a complete sensor unit.

[0010] As a further description of the above technical solution:

[0011] The strain gauge and the strain gauge holder are detachably connected.

[0012] As a further description of the above technical solution:

[0013] The optical fiber inside the packaging housing is a bare optical fiber, and the outside of the packaging housing is an armored optical fiber.

[0014] The present utility model has the following beneficial effects:

[0015] In the present utility model, by simplifying the structure and optimizing the material selection, the production cost is reduced, the number of sensor components is reduced, and the assembly is made more convenient and fast; the strain gauge type structure is adopted to enhance the stability and reliability of the sensor; the sensor has its own temperature compensation, eliminating the problem that the grating is easily affected by temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is an overall structural schematic diagram of a grating displacement sensor of the present utility model;

[0017] Figure 2 is an overall side-sectional schematic diagram of a grating displacement sensor of the present utility model;

[0018] Figure 3 is a top-view structural schematic diagram of a grating displacement sensor of the present utility model;

[0019] Figure 4 is a front view structural schematic diagram of the appearance of a grating displacement sensor of the present utility model;

[0020] Legend:

[0021] 1. Pull rod; 2. Tensile spring; 3. Encapsulation cover; 4. Bare optical fiber; 5. Armored optical fiber; 6. Displacement grating; 7. Strain gauge; 8. Strain gauge holder; 9. Temperature compensation grating; 10. Encapsulation housing; 11. Strain gauge and spring connector; 12. Encapsulation housing sleeve. Specific implementation mode

[0022] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with 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 the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present utility model.

[0023] Referring to FIGS. 1-4, the present utility model provides a grating displacement sensor, including an encapsulation housing 10 and an encapsulation cover 3. An encapsulation cover 3 is provided on one side of the encapsulation housing 10. A strain gauge 7 is provided on the inner wall of the encapsulation housing 10. A strain gauge holder 8 is provided at the connection between the strain gauge 7 and the encapsulation housing 10. A displacement grating 6 is fixedly provided on the surface of the strain gauge 7. A temperature compensation grating 9 is provided on one side of the displacement grating 6. One side of the strain gauge 7 is connected to a spring connector 11. A tensile spring 2 is provided on the other side of the spring connector 11. A pull rod 1 is provided on the other side of the tensile spring 2. An encapsulation housing sleeve 12 is provided outside the tensile spring 2 and the pull rod 1. Through holes are symmetrically provided on both sides of the encapsulation housing 10. A whole optical fiber penetrates through the encapsulation housing 10 and the through holes.

[0024] When in use, first, fix the top of the pull rod 1 at the other end of the object to be detected, and then fix the sensor at a suitable position to ensure that the tensile spring 2 has a suitable tensile amount and ensure that the displacement direction is the same as the tensile direction; secondly, when the monitored object moves, the pull rod 1 will generate a pulling force on the tensile spring 2, causing the tensile spring 2 to generate a corresponding elastic force. The strain gauge 7 connected to the tensile spring 2 will generate a corresponding stress change with the change of the elastic force, and the displacement grating 6 fixed on the strain gauge 7 will also cause a change in wavelength due to the change of stress; finally, cooperate with detecting the change amount of the central wavelength of the displacement grating 6 to calculate the actual displacement amount of the object to be measured; this sensor is equipped with a temperature compensation grating 9, which can fundamentally eliminate the interference of temperature on the fiber grating sensor; this device calculates the actual displacement amount of the object to be measured by detecting the offset amount of the resonant wavelength of the displacement grating 6.

[0025] The spring connector 11 passes through the encapsulation cover 3 and is connected to the tension spring 2; it is convenient to drive the change of the tensile force of the tension spring 2 through the movement of the pull rod 1, so that the spring connector 11 drives the strain gauge 7 to produce a cooperative deformation.

[0026] The encapsulation cover 3 is fixedly connected to the encapsulation housing 10 to form a complete sensor unit, and the device is sealed by the fitting of the encapsulation cover 3 and the encapsulation housing 10.

[0027] The strain gauge 7 and the strain gauge holder 8 are detachably connected; the convenience of device disassembly is enhanced through this detachable design.

[0028] The optical fiber inside the encapsulation housing 10 is a bare optical fiber 4, and the outside of the encapsulation housing 10 is an armored optical fiber 5; the armored optical fiber 5 can protect the optical fiber and prevent the optical fiber from being damaged during installation and testing, and is installed at both ends of the housing.

[0029] Working principle:

[0030] The maximum tensile distance of the pull rod 1 is 100 nm, and the maximum movable distance of the tension spring 2 is also 100 nm. The strain gauge driven by the spring can be stretched by more than 10,000 microstrains, and the change in the optical fiber wavelength can reach more than 2 nm, completing the production of a high-precision sensor; the end of the tension spring 2 is connected to the strain gauge 7 through the strain gauge and the spring connector 11. The displacement of the tension spring is linearly related to the strain gauge. Specifically, the reset of the tension spring 2 can make the strain gauge 7 automatically return to its original position.

[0031] When in use; first, fix the top of the pull rod 1 at the other end of the object to be detected, and then fix the sensor at a suitable position to ensure that the tension spring 2 has a suitable tensile amount and ensure that the displacement direction is the same as the tensile direction; second, when the monitored object moves, the pull rod 1 will exert a pulling force on the tension spring 2, causing the tension spring 2 to generate a corresponding elastic force. The strain gauge 7 connected to the tension spring 2 will produce a corresponding stress change with the change of the elastic force, and the displacement grating 6 fixed on the strain gauge 7 will also cause a change in wavelength due to the stress change; finally, the actual displacement of the measured object is calculated by detecting the change in the central wavelength of the displacement grating 6.

[0032] This sensor is equipped with a temperature compensation grating 9, which can fundamentally eliminate the interference of temperature on the fiber grating sensor. The displacement grating 6 is fixed by a strain gauge 7. The grating area of the displacement grating 6 is placed in the groove of the strain gauge 7 and fixed with epoxy resin 353ND glue. The strain gauge 7 is suspended and fixed by a strain gauge holder 8. This method has the characteristics of high sensitivity, accurate precision and strong stability. The groove is filled with silicone oil for isolation and protection. At the same time, this device is modified by using the strain gauge 7, which greatly reduces the cost of the displacement sensor and increases the convenience of installing this device, thus greatly reducing some troubles brought by the installation of this sensor. When maintaining, only some accessories of this sensor need to be replaced, instead of replacing the whole sensor, which greatly reduces the maintenance cost.

[0033] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A grating displacement sensor, comprising a packaging shell (10) and a packaging cover (3), characterized in that: A packaging cover (3) is provided on one side of the packaging shell (10), a strain gauge (7) is provided on the inner wall of the packaging shell (10), a strain gauge holder (8) is provided at the connection between the strain gauge (7) and the packaging shell (10), a displacement grating (6) is fixedly provided on the surface of the strain gauge (7), a temperature compensation grating (9) is provided on one side of the displacement grating (6), a spring connector (11) is connected to one side of the strain gauge (7), a tension spring (2) is provided on the other side of the spring connector (11), a pull rod (1) is provided on the other side of the tension spring (2), a packaging shell sleeve (12) is provided on the outside of the tension spring (2) and the pull rod (1), through holes are symmetrically provided on both sides of the packaging shell (10), and a whole optical fiber runs through the inside of the packaging shell (10) and the through hole.

2. A grating displacement sensor according to claim 1, characterized in that: The spring connector (11) penetrates the packaging cover (3) and is connected to the tension spring (2).

3. A grating displacement sensor according to claim 2, characterized in that: The packaging cover (3) is fixedly connected to the packaging shell (10) to form a complete sensor as a whole.

4. A grating displacement sensor according to claim 3, characterized in that: The strain gauge (7) and the strain gauge fixture (8) are detachably connected.

5. A grating displacement sensor according to claim 4, characterized in that: The optical fiber inside the packaging shell (10) is a bare optical fiber (4), and the outer side of the packaging shell (10) is an armored optical fiber (5).

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