Elastic element based on generalized involute structural beam and acceleration sensor

Abstract

The invention discloses an elastic element based on a generalized involute structural beam and an acceleration sensor, the elastic element comprises a first mass block, a second mass block and an elastic diaphragm, and the first mass block and the second mass block are symmetrically arranged on the upper surface and the lower surface of the elastic diaphragm respectively; the elastic diaphragm is provided with at least one generalized involute-shaped hollow groove, so that a plurality of generalized involute beams are formed in the radial direction of the elastic diaphragm, and a multi-beam parallel structure is formed; the generalized involute-shaped hollow-out groove is formed in the direction from the edge of the mass block to the edge of the elastic diaphragm; the generalized involute beam forms a flexible hinge of the elastic element and is matched with the first mass block and the second mass block to extend the length of the flexible hinge. The involute type introduction of the hollowed-out grooves can determine the optimal base circle radius and expansion coefficient, the layout of the spiral beams is flexibly adjusted, the transverse rigidity of the diaphragm is effectively improved by increasing the number of the beams, and crosstalk caused by transverse acceleration is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical fiber sensing, in particular to an elastic element based on a generalized involute structure beam and an acceleration sensor. BACKGROUND

[0002] Sensor technology is widely used in modern scientific and technological development, and plays a crucial role in industrial automation, environmental monitoring, biomedicine, national security and many other fields. Although traditional electrical sensors are widely used, their performance is often limited in harsh or special environments such as strong electromagnetic interference, flammable and explosive, high temperature and pressure, strong corrosion, or long-distance distributed monitoring.

[0003] Optical fiber sensors are a new type of sensor developed to overcome these challenges. Optical fiber sensors use optical fibers as a sensing and signal transmission medium, and detect changes in one or more parameters (such as intensity, phase, wavelength, polarization state, mode distribution, etc.) of light propagating in the optical fiber to sense changes in external physical quantities. Its core advantage lies in its intrinsic safety (no electric spark), resistance to electromagnetic interference, corrosion resistance, small size, light weight, high sensitivity, fast response, ease of implementation of distributed and quasi-distributed sensing, and compatibility with existing optical fiber communication networks.

[0004] In recent years, optical fiber Fabry-Perot acceleration sensors have been one of the research hotspots. Optical fiber Fabry-Perot acceleration sensors use optical Fabry-Perot interference principles to achieve high-precision measurement by detecting small changes in cavity length caused by acceleration. Its core advantage lies in its resistance to electromagnetic interference, intrinsic safety, resistance to harsh environments and long-distance transmission capabilities, making it irreplaceable in aerospace, energy and power, petrochemical, large-scale structure monitoring and other special or high-demand fields. Despite the challenges of complex demodulation and temperature sensitivity, its performance and cost-effectiveness continue to improve with the advancement of optical fiber technology and demodulation algorithms, and it has a broad application prospect.

[0005] The generalized involute structure beam model belongs to the intersection of mechanical structures, sensing technology and vibration energy harvesting, and its core is to use generalized involute as the geometric shape of the beam to obtain special mechanical properties such as low stiffness, high linearity, large deformation capability and specific stress and strain distribution. Therefore, in view of the specific frequency response, sensitivity and anti-lateral interference requirements of the acceleration sensor, the diaphragm is combined with the generalized involute structure beam model, and the physical quantity is amplified to mechanical deformation, so that the length of the generalized involute beam is maximized in the limited area of the diaphragm. SUMMARY

[0006] In order to make the optical fiber sensor have better sensitivity, the application provides an elastic element and an acceleration sensor based on a generalized involute structure beam. By opening a specific involute hollow pattern on the diaphragm, the complete flat diaphragm is converted into an elastic element composed of a flexible hinge and a rigid mass composed of an involute linear beam.

[0007] The first aspect of the application is to provide an elastic element based on a generalized involute structure beam, which comprises a first mass, a second mass and an elastic diaphragm, the first mass and the second mass are symmetrically arranged on the upper surface and the lower surface of the elastic diaphragm respectively; at least one generalized involute hollow groove is opened on the elastic diaphragm, the generalized involute hollow groove forms a plurality of generalized involute beams in the radial direction of the elastic diaphragm, and the generalized involute hollow groove is opened along the mass edge to the edge direction of the elastic diaphragm; the generalized involute beam forms a flexible hinge of the elastic element, which cooperates with the first and second masses to extend the flexible hinge length.

[0008] Further, the first mass and the second mass are fixed to the central region of the elastic diaphragm.

[0009] Further, at least two generalized involute hollow grooves are opened on the elastic diaphragm, and the generalized involute hollow grooves are distributed at equal angles along the same circumferential direction.

[0010] The elastic diaphragm provided with the generalized involute type hollow groove with controllable expansion degree is a linear beam structure with a certain width based on the generalized involute model, the number of linear beams is adjusted by the number of hollow grooves, and a multi-beam parallel structure is formed.

[0011] Further, the number, length and width of the generalized involute hollow groove are set according to actual needs, and the longitudinal stiffness and transverse stiffness of the elastic diaphragm are adjusted.

[0012] Under the same size, the longer the length of the generalized involute beam, the narrower the width of the beam, and the thinner the thickness of the diaphragm, the smaller the longitudinal stiffness and the higher the sensitivity; the more the number of linear beams, the greater the transverse stiffness and the stronger the resistance to transverse cross sensitivity; the parameters such as the number, length, width and thickness of the generalized involute beam can be adjusted according to the measurement requirements.

[0013] Further, the acquisition of the involute type of the generalized involute type hollow groove comprises:

[0014] On the mathematical model of the involute curve, an expansion coefficient for controlling the expansion degree of the involute is introduced to generate the line shape of the generalized involute type hollow groove, which can control the expansion degree of the generated curve;

[0015] The base circle radius and development coefficient of the involute shape mentioned above The determination includes the following steps:

[0016] Step 1: Within the given radius range Inside, with Let R be the initial base circle radius. b And with 1 as the initial expansion coefficient ;

[0017] Step 2: In each set of parameters Below, calculation Minimum eccentricity within the interval ;

[0018] Step 3: When Satisfying structural constraints Then, further calculate the development angle and rotation angle of the involute ( );in For the number of arms of the involute, It is the sum of the width of the elastic beam and the width of the trench;

[0019] Step 4: Gradually reduce the base circle radius R b To the preset minimum value; for each base circle radius, sequentially change the expansion coefficient. And repeat steps two and three for iterative calculation;

[0020] Step 5: Compare the rotation angle difference values ​​under different parameter combinations The optimal combination of parameters that yields the maximum rotation angle is selected to determine the best base circle radius and expansion coefficient.

[0021] A second aspect of the present invention provides an accelerometer, comprising a single-mode optical fiber, a ferrule, a substrate, and the aforementioned elastic element for a diaphragm-type accelerometer; a groove is formed on the top of the substrate, and the elastic diaphragm is fixedly disposed on the top of the substrate, with a first mass block located within the groove of the substrate; a single-mode optical fiber with a ferrule inserted is inserted from the bottom of the substrate toward the groove, and the fiber end face of the single-mode optical fiber and the lower surface of the first mass block facing the fiber end face serve as a first reflective surface and a second reflective surface, with an acceleration-sensitive Fabry-Perot microcavity formed between the two reflective surfaces.

[0022] Furthermore, the insert is made of ceramic, and the substrate is made of glass.

[0023] Furthermore, both the first and second mass blocks are cylindrical and have equal mass.

[0024] The beneficial effects of this invention are as follows:

[0025] The elastic element based on the generalized involute structure beam is based on a generalized involute model, a hollow groove is formed on the elastic diaphragm to form a linear beam structure with a certain width, and a multi-beam parallel structure is formed;

[0026] The elastic element can maximize the length of the linear beam in the limited area of the elastic diaphragm, thereby improving the axial sensitivity of the sensor;

[0027] The generalized involute type hollow groove is designed by introducing the development coefficient for controlling the development degree of the involute, the spiral beam layout can be flexibly adjusted, the transverse stiffness of the diaphragm can be effectively improved by increasing the number of beams, and the cross talk caused by the transverse acceleration is reduced;

[0028] The acceleration sensor provided with the elastic element has the advantages of small volume, high temperature resistance, easy packaging, can be mass produced, and is suitable for application in multiple scenes. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of the acceleration sensor of embodiment 1;

[0030] Figure 2 It is a bottom view of the elastic element of the acceleration sensor of embodiment 1;

[0031] Figure 3 It is a principle diagram of the generalized involute structure used by the elastic diaphragm of embodiment 1;

[0032] Figure 4 It is a top view of the elastic element of the acceleration sensor of embodiment 2.

[0033] Among them,

[0034] 1: single mode optical fiber; 2: ferrule; 3: base; 4: elastic diaphragm; 4-1: generalized involute type hollow groove;

[0035] 4-2: first mass; 4-3: second mass; 4-4: generalized involute beam; 5: optical fiber end face; 6: lower surface. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical scheme, beneficial effects and significant progress of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely in combination with the drawings provided in the examples of the present application. Obviously, all the described embodiments are only part of the embodiments of the present application, not all the embodiments; based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0037] In the description of the present application, unless otherwise explicitly specified and limited, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance; the term "multiple" refers to two or more than two; unless otherwise specified or stated, the terms "connection", "fixation" and the like should be broadly understood, for example, "connection" can be fixed connection, or detachable connection, or integrally connected, or electrically connected; "connection" can be directly connected, or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0038] Embodiment 1

[0039] As Figure 1 shown, an optical fiber Fabry-Perot acceleration sensor, comprising a single-mode optical fiber 1, a ferrule 2, a substrate 3, a generalized involute structure elastic element; the substrate 3 is of glass material, and a through hole is formed along the central axis direction thereof, and a flat-bottomed groove is formed inward from the upper surface of the substrate 3, the ferrule 2 is fixedly connected in the through hole, the ferrule 2 is of ceramic material, and the single-mode optical fiber 1 is inserted and fixed in the ferrule 2, and the fiber end face 5 of the single-mode optical fiber 1 is flush with the groove bottom surface of the substrate 3, playing a role of optical transmission.

[0040] The generalized involute structure elastic element includes a first mass block 4-2, a second mass block 4-3 and an elastic diaphragm 4. The profile of the elastic diaphragm 4 is adapted to the outer profile of the upper surface of the substrate 3, and the edge of the elastic diaphragm 4 is fixedly arranged at the edge of the upper surface of the substrate 3, so that the elastic diaphragm 4 and the groove of the substrate 3 form a cavity. A cylindrical mass block is fixedly arranged on the upper surface and the lower surface of the elastic diaphragm 4 along the central axis direction of the elastic diaphragm 4, the mass block located in the cavity is the first mass block 4-2, and the mass block away from the cavity is the second mass block 4-3; the two mass blocks are correspondingly fixed on the upper and lower surfaces of the diaphragm, so that the elastic diaphragm 4, the first mass block 4-2, the second mass block 4-3 and the single-mode optical fiber 1 are arranged along the central axis of the substrate 3. The fiber end face 5 of the single-mode optical fiber 1 and the lower surface 6 of the first mass block 4-2 in the cavity facing the fiber end face serve as the first reflecting surface and the second reflecting surface, and the acceleration-sensitive Fabry-Perot microcavity is formed between the two reflecting surfaces. The cavity length of the Fabry-Perot microcavity is the length between the two reflecting surfaces, and when the sensor is subjected to acceleration, the elastic diaphragm 4 is deformed through inertia, thereby changing the cavity length.

[0041] As Figure 2The elastic diaphragm 4 is shown, and three generalized involute type hollow grooves 4-1 are opened on the elastic diaphragm 4. The generalized involute type hollow grooves are curve belt grooves opened around the first / second mass block, and each generalized involute type hollow groove 4-1 penetrates the elastic diaphragm 4 and spirally radiates from a certain distance (the minimum base circle radius of the given involute to be generated ) from the edge of the mass block to the edge of the elastic diaphragm. The diaphragm area of the adjacent two generalized involute type hollow grooves 4-1 in the radial direction of the elastic diaphragm 4 is a generalized involute beam 4-4. The elastic diaphragm 4 forms a plurality of generalized involute beams 4-4 through the opening of the generalized involute type hollow grooves 4-1, so that the length of the generalized involute beam can be maximized in a limited area of the diaphragm.

[0042] Figure 3 The principle diagram of the generalized involute type hollow groove 4-1 in the embodiment is shown. It is a generalized involute based on the mathematical model of involute curve. The process is to find the optimal solution of the base circle radius and the coefficient by simulating the generation process of the involute arc arm through numerical iteration. The base circle radius is the starting circle of the rolling development of the involute. It determines the geometric dimension and distribution of the involute in space. The specific steps are as follows:

[0043] Step one: based on the mathematical model of the involute curve, the involute generated from any point A to point B on the elastic diaphragm is At this time , is tangent to point B of the elastic diaphragm;

[0044] Step two: on the mathematical model of the involute curve, the development coefficient α that controls the development degree of the involute is introduced to generate the line shape of the generalized involute type hollow groove 4-1. The development degree of the generated curve can be controlled;

[0045] Wherein the determination of the development coefficient α includes the following steps:

[0046] Step 21: in the given radius range , take as the initial base circle radius R b , and take 1 as the initial development coefficient ;

[0047] Step 22: under each group of parameters , calculate the minimum eccentricity in the interval . The parameter is used to measure the compactness of the involute;

[0048] Step 23: when satisfies the structural constraint (where For the number of arms of the involute, When the sum of the elastic beam width and the groove width is given, the development angle and rotation of the involute are further calculated. );

[0049] Step 24: Gradually reduce the base circle radius R b Up to the preset minimum value (slightly greater than 0); for each base circle radius, successively change the expansion factor. (Value range 1 → 0), and repeat steps 22 to 23 for iterative calculation to analyze its influence on the involute unfolding shape;

[0050] Step 25: Compare the rotation angle difference values ​​under different parameter combinations The optimal combination of parameters that yields the maximum rotation angle is selected to determine the best base circle radius and development coefficient. This process achieves automatic optimization of the involute arm development characteristics while satisfying geometric and structural constraints, maximizing the elastic beam length within a limited region to improve sensitivity.

[0051] Step 3: Import the expansion coefficient α into the formula Generate the linear shape of the generalized involute hollow groove 4-1 The curvature of this generalized involute can be controlled, allowing for longer curve lengths within the same area constraint. A larger expansion coefficient α results in a more extended involute; a smaller expansion coefficient α results in a more contracted involute. When the base circle radius R... b When the expansion coefficient α is constant, the larger the involute distribution, the denser the distribution; when the expansion coefficient α is constant, the base circle radius R b The smaller the value, the denser the involute curve distribution. Excessive curve density can lead to uneven width and overlap of the generalized involute beam, while excessively sparse curves result in low space utilization. Therefore, controlling the eccentricity and its conditions is crucial. (in For the number of arms of the involute, The constraint is achieved by combining the width of the elastic beam with the width of the trench.

[0052] In this embodiment, three generalized involute grooves 4-1 are formed on the elastic diaphragm 4. The grooves are integrally formed by etching. That is, with three generalized involute beams 4-4, the radius of the diaphragm 4 is 10mm, and the maximum distance between the beams 4-4 and the center of the diaphragm is 7mm (this 7mm corresponds to r2, that is, the part of the groove farthest from the center). When the width of the three involute beams 4-4 is 1mm, the development coefficient α and the base circle radius R are obtained. bThe optimal solutions of the above two equations are 0.55 and 1.56 mm, respectively. This optimization aims to maximize the length of the beam while preventing the beam from crossing, thereby achieving flexible parameterization and design of the multi-beam structure. When the diaphragm thickness is 0.1 mm, the radii of the first mass block 4-2 and the second mass block 4-3 on the upper and lower sides are both 2.5 mm, and the thicknesses of the first mass block 4-2 and the second mass block 4-3 are both 3 mm, the simulation results show that the axial sensitivity of the Fabry-Perot acceleration sensor is 16.178 μm / g, and when a lateral acceleration and an axial acceleration of 1 g are applied to the sensor, respectively, the axial deformation is still 16.178 μm, and the lateral acceleration has little effect on the axial deformation.

[0053] Therefore, by adjusting the base circle radius and the development coefficient a, the involute layout is controlled so that the elastic diaphragm 4 maximizes the length of the generalized involute beam, thereby improving the sensitivity of the fiber Fabry-Perot acceleration sensor.

[0054] In use, when an axial acceleration is applied, the first and second mass blocks located on the upper and lower surfaces of the elastic diaphragm 4 generate inertial forces, which drive the elastic diaphragm 4 to deform. Due to the presence of the generalized involute type hollow groove 4-1, the deformation is mainly concentrated on the generalized involute beam 4-4. The geometric characteristics of the generalized involute make the generalized involute beam 4-4 have extremely low stiffness when rotating around its tangent direction and the stress distribution is uniform, thereby enabling the elastic diaphragm 4 to achieve large stroke and high linearity deformation in the axial direction. Compared with the conventional flat diaphragm of the same thickness and mass, the diaphragm structure with the beam of the present application has significantly improved axial sensitivity, while avoiding edge stress concentration, improving linearity and fatigue life.

[0055] Example 2

[0056] As Figure 4 shown, a fiber Fabry-Perot acceleration sensor includes a single-mode optical fiber 1, a ferrule 2, a substrate 3, and a generalized involute structure elastic element. The generalized involute structure elastic element includes a first mass block 4-2, a second mass block 4-3, and an elastic diaphragm 4.

[0057] Example 2 is basically the same as Example 1, except that the elastic diaphragm 4 is provided with a generalized involute type hollow groove 4-1, the generalized involute type hollow groove 4-1 is arranged in a spiral shape, and the generalized involute type hollow groove 4-1 forms a plurality of generalized involute beams 4-4 in the radial direction of the elastic diaphragm.

[0058] Furthermore, it should be understood that although the specification is described in terms of embodiments, not every embodiment contains all features of a particular embodiment, and some embodiments contain none of the features of a particular embodiment. The specification, therefore, is not to be taken in a narrow, limited sense, and broad application is to be allowed.

Claims

1. An elastic element based on a generalized involute beam structure, characterized in that, The elastic element includes a first mass block (4-2), a second mass block (4-3), and an elastic diaphragm (4). The first mass block (4-2) and the second mass block (4-3) are symmetrically arranged on the upper and lower surfaces of the elastic diaphragm (4), respectively. At least one generalized involute hollow groove (4-1) is opened on the elastic diaphragm (4). The generalized involute hollow groove (4-1) forms multiple generalized involute beams (4-4) in the radial direction of the elastic diaphragm. Moreover, the generalized involute hollow groove (4-1) is opened from the edge of the mass block toward the edge of the elastic diaphragm. The generalized involute beams (4-4) form the flexible hinge of the elastic element, which cooperates with the first and second mass blocks to extend the length of the flexible hinge.

2. The elastic element based on a generalized involute beam structure according to claim 1, characterized in that, The first mass block (4-2) and the second mass block (4-3) are fixed to the central region of the elastic diaphragm.

3. The elastic element based on a generalized involute beam structure according to claim 1, characterized in that, At least two generalized involute grooves (4-1) are formed on the elastic diaphragm, and the generalized involute grooves (4-1) are distributed at equal angular intervals along the same circumferential direction.

4. The elastic element based on a generalized involute beam structure according to claim 1, characterized in that, The longitudinal and transverse stiffness of the elastic diaphragm (4) can be adjusted by setting the number, length and width of the generalized involute hollow grooves (4-1).

5. The elastic element based on a generalized involute beam structure according to claim 1, characterized in that, Obtaining the involute shape of the generalized involute hollow groove (4-1) includes: In the mathematical model of the involute curve, an expansion coefficient is introduced to control the degree of involute expansion. The line shape of the generalized involute hollow groove (4-1) is generated, and the degree of unfolding of the generated curve can be controlled; The base circle radius and development coefficient of the involute shape mentioned above The determination includes the following steps: Step 1: Within the given radius range Inside, with Let R be the initial base circle radius. b And with 1 as the initial expansion coefficient ; Step 2: In each set of parameters Below, calculation Minimum eccentricity within the interval ; Step 3: When Satisfying structural constraints Then, further calculate the development angle and rotation angle of the involute ( );in For the number of arms of the involute, It is the sum of the width of the elastic beam and the width of the trench; Step 4: Gradually reduce the base circle radius R b To the preset minimum value; for each base circle radius, sequentially change the expansion coefficient. And repeat steps two and three for iterative calculation; Step 5: Compare the rotation angle differences under different parameter combinations, select the optimal parameter combination that yields the maximum rotation angle, and determine the best base circle radius and development coefficient.

6. An acceleration sensor, characterized in that, The invention includes a single-mode optical fiber (1), a ferrule (2), a substrate (3), and an elastic element based on a generalized involute structure beam according to any one of claims 1-5; a groove is formed on the top of the substrate (3), and the elastic diaphragm (4) is fixedly disposed on the top of the substrate (3), and a first mass block (4-2) is located in the groove of the substrate (3); a single-mode optical fiber (1) with a ferrule (2) is inserted from the bottom of the substrate (3) toward the groove, and the fiber end face (5) of the single-mode optical fiber (1) and the lower surface (6) of the first mass block (4-2) facing the fiber end face serve as the first and second reflective surfaces, and an acceleration-sensitive Fabry-Perot microcavity is formed between the two reflective surfaces.

7. The accelerometer according to claim 6, characterized in that, The insert (2) is made of ceramic, and the base (3) is made of glass.

8. The accelerometer according to claim 6, characterized in that, The first mass block (4-2) and the second mass block (4-3) are both cylindrical and have the same mass.

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