Flange relative displacement measuring device and method based on capacitance ranging principle

Abstract

The invention discloses a flange relative displacement measuring device and method based on a capacitance ranging principle. The device comprises a first flange plate and a second flange plate which are oppositely arranged and connected through bolts. The lower end face of the first flange plate is provided with a first group of capacitor polar plates comprising first to sixth polar plates, wherein the first to fifth polar plates are squares with the side length being L, and the fifth polar plate is located in the center. The upper end face of the second flange plate is provided with a second group of capacitor polar plates comprising a seventh polar plate and an eighth polar plate. According to the method, the reference capacitance and the real-time capacitance between the polar plates are obtained through the capacitance measuring instrument, the axial displacement delta Z is calculated through the capacitance change between the sixth polar plate and the eighth polar plate, then the in-plane displacement direction is judged according to the non-zero condition of the capacitance between the seventh polar plate and the four corner polar plates, and finally the in-plane displacement delta X and the in-plane displacement delta Y are calculated. According to the invention, non-contact, synchronous and high-precision measurement of the three-dimensional relative displacement of the flange is realized, the structure is simple, the environmental adaptability is high, and the device is suitable for on-line monitoring and safety early warning.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of mechanical structure state monitoring and precision measurement, and particularly relates to a flange relative displacement measurement device and method based on a capacitive distance measurement principle. BACKGROUND

[0002] Flange connection is one of the most widely used static sealing connection methods in the industrial field. It realizes medium sealing and load transmission by pre-tightening force of bolts to press two flanges with sealing gaskets. The integrity of the flange joint is crucial to the safe operation of the entire system. Under complex working conditions (such as high temperature, high pressure, alternating load, vibration, impact and long-term creep, etc.), flange connection may occur relaxation, warping, deflection or gasket failure, resulting in relative displacement between flange faces (including separation along the axial direction, misalignment along the radial direction and in-plane torsion). If these small displacements cannot be discovered and corrected in time, it will trigger a chain reaction of sealing leakage, stress concentration, bolt failure, etc., and eventually may lead to equipment downtime, production loss, and even catastrophic accidents. Therefore, real-time monitoring of the flange connection state, especially the accurate measurement of the relative displacement between flange plates, has important engineering significance and safety value. At present, the measurement technology for flange relative displacement or end face gap mainly includes the following categories: Mechanical contact measurement method: using contact gauges such as dial gauge, micrometer or inductance micrometer, etc., to measure by directly abutting the probe on the flange end face or side face. This method is mature in technology and low in cost, but it is offline or point inspection measurement, which cannot realize continuous online monitoring. The measurement efficiency is low, and the contact measurement has problems such as mechanical wear and large human reading error, which has poor applicability in harsh conditions such as high speed, high temperature or strong vibration.

[0003] Optical non-contact measurement method: including laser triangulation method, laser interference method, visual measurement method, etc. This kind of method has high precision and fast response, but the equipment is usually very expensive, and it is extremely sensitive to environmental conditions (such as dust, oil stains, water vapor, ambient light, vibration), and the system installation, calibration and maintenance are complex. In industrial field, especially in harsh environment of heavy industry, the stability and reliability of optical system face severe challenges.

[0004] Eddy current sensor measurement method: using eddy current effect to measure the distance between the surface of the metal conductor and the sensor probe. This method is a non-contact measurement with good dynamic response. However, its measurement accuracy is easily affected by the electromagnetic properties (such as permeability, conductivity) of the measured material and temperature, and it is usually a single-point measurement. If you want to measure three-dimensional displacement, you need to arrange multiple sensors and perform complex spatial calculation, which has high system integration and cost, and the sensor probe is relatively large in size, which is difficult to install in space-limited flange connection.

[0005] In summary, existing technologies generally suffer from the following defects and shortcomings: 1. Difficulty in achieving three-dimensional synchronous measurement: Most methods can only measure the distance or displacement in a single direction. To obtain a three-dimensional displacement vector, multiple sets of sensors need to be deployed and complex spatial geometric calculations need to be performed, making the system complex.

[0006] 2. Weak online monitoring capability: Traditional mechanical methods are difficult to automate and achieve continuous online monitoring.

[0007] 3. Poor environmental adaptability: High-precision optical methods are too sensitive to industrial environments and lack stability.

[0008] 4. Poor economic efficiency and ease of installation: Existing high-precision online monitoring solutions are often costly, and the installation, calibration and maintenance processes are complex, making it difficult to promote on a large scale.

[0009] Therefore, there is an urgent need to invent a new method and device that can overcome the above-mentioned defects and achieve high-precision, high-reliability, and low-cost online measurement of the three-dimensional relative displacement of flange connections. Summary of the Invention

[0010] The purpose of this invention is to provide a flange relative displacement measuring device and method based on the principle of capacitance ranging. This device has a compact structure, is easy to install, and can be directly integrated into standard or non-standard flange connections to achieve synchronous sensing of three-dimensional displacement. Based on a specific capacitor plate configuration and algorithm, the relative translational displacement of the flange in the X, Y, and Z coordinate axes can be accurately and quickly calculated from multiple capacitance measurements.

[0011] To achieve the above objectives, the present invention proposes the following technical solution: a flange relative displacement measuring device based on the principle of capacitance ranging, comprising: a first flange, the lower end face of the first flange being a first reference surface; and a second flange, the upper end face of the second flange being a second reference surface opposite to the first reference surface. The first set of capacitor plates is installed in the four corner areas of the first reference surface of the first flange. The first set of capacitor plates includes a first plate, a second plate, a third plate, a fourth plate, a fifth plate, and a sixth plate. The second set of capacitor plates is installed in the four corner areas of the second reference surface of the second flange. The second set of capacitor plates includes a seventh plate and an eighth plate. After the first flange and the second flange are fastened by the bolts and nuts, the first set of capacitor plates and the second set of capacitor plates are vertically opposite each other. The capacitance measuring instrument is electrically connected to each plate in the first group of capacitor plates and each plate in the second group of capacitor plates via wires, and is used to measure the capacitance value between selected plate pairs in the first group of capacitor plates and the second group of capacitor plates. The data communication module is used to send the capacitance value between the first group of capacitor plates and the selected plate pair in the second group of capacitor plates collected by the capacitance measuring instrument to the computer. Computers are used to calculate and display real-time and historical displacement data and alarm information.

[0012] Furthermore, the fifth electrode plate is located within the area enclosed by the first electrode plate, the second electrode plate, the third electrode plate, and the fourth electrode plate, and the four sides of the fifth electrode plate coincide with one side of the first electrode plate, the second electrode plate, the third electrode plate, and the fourth electrode plate, respectively. The vertical projection of the seventh electrode plate onto the first reference plane is completely or partially overlapped with the fifth electrode plate. The vertical projection of the eighth electrode plate onto the first reference plane is entirely within the projection range of the sixth electrode plate.

[0013] Furthermore, the first, second, third, fourth, fifth, seventh, and eighth electrode plates are square electrode plates with equal side lengths of L; the sixth electrode plate is a square electrode plate with a side length of 3L.

[0014] Furthermore, the first electrode plate, the second electrode plate, the third electrode plate, and the fourth electrode plate are centrally symmetrically distributed around the fifth electrode plate.

[0015] Furthermore, the capacitance measuring instrument is a multi-channel capacitance measuring instrument that simultaneously or time-divisionally measures the capacitance value between the seventh plate and the first, second, third, fourth, and fifth plates, as well as the capacitance value between the eighth plate and the sixth plate.

[0016] Furthermore, the first capacitor plate group and the second capacitor plate group are formed by fabricating conductive patterns on a flexible insulating substrate or a rigid insulating substrate, and are fixed to the first reference plane and the second reference plane by means of bonding, snapping or mechanical fastening.

[0017] This invention also proposes a measurement method for a flange relative displacement measuring device based on the above-mentioned capacitance ranging principle, comprising: Reference capacitance acquisition steps: With the first flange and the second flange in their initial tightened state, measure and record the reference capacitance value using the capacitance measuring instrument, including at least the first reference capacitance between the seventh plate and the fifth plate. and the second reference capacitor between the eighth plate and the sixth plate. ; Real-time capacitance monitoring steps: During the monitoring process, the capacitance values ​​between the seventh plate and the first, second, third, fourth, and fifth plates are measured in real time using the capacitance measuring instrument. , , , , and the real-time capacitance value between the eighth electrode and the sixth electrode. ; Axial displacement calculation steps: Based on the real-time capacitance value With the second reference capacitor Based on the relationship between the changes, calculate the relative displacement ΔZ between the first flange and the second flange along the axial direction; In-plane displacement determination and calculation steps: based on the real-time capacitance value , , , Whether the value exceeds a preset sensitivity threshold is used to determine the direction quadrant of the in-plane displacement; based on the real-time capacitance value... , , , The capacitance value greater than the threshold, the real-time capacitance value Using the side length L, calculate the relative displacements ΔX and ΔY between the first flange and the second flange in two orthogonal directions within the plane.

[0018] Furthermore, in the axial displacement calculation step, the formula for calculating ΔZ is:

[0019] in, is the dielectric constant of the capacitor.

[0020] Furthermore, the calculation of the relative displacements ΔX and ΔY between the first flange and the second flange in two orthogonal directions within the plane is specifically as follows:

[0021] In the formula and These are the real-time capacitance values ​​between the first, second, third, or fourth plate and the seventh plate, respectively, which are related to the displacement direction. , , or ; This is the real-time capacitance value between the fifth and seventh plates.

[0022] Furthermore, it also includes displacement synthesis and output steps: synthesizing the calculated ΔX, ΔY, and ΔZ into a three-dimensional displacement vector, and then displaying, storing, or transmitting it; Warning step: Compare the magnitude of the three-dimensional displacement vector or the absolute value of its component in any direction with a preset safety threshold. If the threshold is exceeded, an alarm signal is generated.

[0023] Beneficial effects: 1. This invention, through a combination of a central electrode and four corner electrodes, can simultaneously analyze the displacement components in the X, Y, and Z directions by measuring only a limited number of pairs of electrodes. This overcomes the complexity and inefficiency of traditional methods that require multiple sensors and multiple measurements to synthesize a three-dimensional vector. Furthermore, the algorithm based on capacitance ratios cleverly eliminates absolute parameters such as dielectric constant and absolute spacing, which are easily affected by the environment. It primarily relies on the inherent dimensions of the electrodes and the relative changes in capacitance, giving the measurement system strong anti-interference capabilities.

[0024] 2. As a purely electrical, non-contact measurement solution, this invention is unaffected by typical industrial environmental factors such as dust, oil, and vibration, avoiding the wear and human error problems inherent in mechanical contact measurements. The system enables real-time, continuous, online monitoring and intelligent early warning of flange relative displacement, providing crucial data support for predictive maintenance and effectively preventing leaks and safety accidents caused by flange loosening or deformation. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the flange installation structure of the present invention; Figure 2 This is a schematic diagram of the capacitor plate structure arranged on the end face (reference plane A) of the first flange of the present invention; Figure 3 This is a schematic diagram of the capacitor plate structure arranged on the end face (reference plane B) of the second flange of the present invention. Figure 4 This is a layout diagram of the capacitor plates of the present invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0027] Example 1: Specific Structure and Installation of the Measuring Device refer to Figure 1The measuring device in this embodiment is used to monitor the connection status of two mating flanges (first flange 1 and second flange 2) on a section of pipeline. The two flanges are connected by four circumferentially distributed high-strength bolts 3 and nuts 4 (nuts are not shown in the figure), with a sealing gasket (not shown) sandwiched in between. The first flange 1 is provided with at least four first screw holes 5, and the second flange 2 is provided with at least four second screw holes 6. The first flange 1 is located above the second flange 2 and is fastened to it by bolts 3 and nuts 4 passing through the first screw holes 5 and the second screw holes 6.

[0028] like Figure 2 As shown, after cleaning, an insulating substrate (such as a polyimide film or ceramic sheet) is glued or fixed to the end face (reference surface A) of the first flange 1. On this insulating substrate, the first set of capacitor plates is fabricated using precision etching or coating processes. Specifically, this includes: a first square plate 11 with a side length of L (e.g., L=10mm), a second plate 12, a third plate 13, a fourth plate 14, and a fifth plate 15. These five plates are arranged in a "cross" plus center layout, with the fifth plate 15 located in the center, and the other four plates located at the four corners of a virtual large square with a side length of L, ensuring minimal spacing between the edges of the plates for insulation. In another empty space on the end face of the first flange, a sixth square plate 16 with a side length of 3L (i.e., 30mm) is fabricated. All plates are made of copper with an anti-oxidation coating. A miniature coaxial wire is led out from the solder joint of each plate, and the wires are then combined and led out through a pre-drilled process hole on the flange.

[0029] like Figure 3 As shown, on the end face (reference plane B) of the second flange 2, an insulating substrate and the seventh square electrode plate 21 and the eighth square electrode plate 22 are installed in a similar manner, each with a side length of L=10mm. The position of the seventh electrode plate 21 should satisfy the following condition: when the two flanges are fully aligned and tightened, its projection completely coincides or mostly coincides with the fifth electrode plate 15 on the first flange, and it is located at the center of the square area formed by the first electrode plate 11, the second electrode plate 12, the third electrode plate 13, and the fourth electrode plate 14. The position of the eighth electrode plate 22 should satisfy the condition that its projection falls entirely within the projection range of the sixth electrode plate 16 and is as centered as possible. The electrode plate extension method is the same as that of the first flange.

[0030] like Figure 2 As shown, the first square electrode plate 11, the second electrode plate 12, the third electrode plate 13, the fourth electrode plate 14, and the fifth electrode plate 15 each consist of two sets, which are respectively installed in the vertical direction of the reference plane A; the sixth electrode plate 16 also consists of two sets, which are respectively installed in the horizontal direction of the reference plane A. Similarly, as... Figure 3As shown, the seventh square electrode plate 21 is installed vertically on the reference plane B, and the eighth square electrode plate 22 is installed horizontally on the reference plane B. This is to more comprehensively measure the flange displacement deviation. If only one set is used, the flange may not have moved on the side with the detection electrode plate, but the opposite side may have moved (e.g., temperature changes or other factors may only cause a corner of the flange to move), which would not accurately reflect the displacement.

[0031] Connect the lead wires from the two sets of plates to a high-precision multi-channel capacitance-to-digital converter (e.g., a circuit board based on the AD7745 / 46 series chip). This converter can perform synchronous measurements at a rate of up to 100Hz. , , , , , These six key capacitance values ​​are used to transmit digital signals to the industrial control computer via RS-485 or Ethernet.

[0032] Example 2: Software implementation and calibration process of the measurement method, combined with Figure 4 As shown Steps for obtaining the reference capacitance: When the first flange 1 and the second flange 2 are in the initial tightened state, measure and record the reference capacitance value using a capacitance meter, including at least the first reference capacitance between the seventh plate 21 and the fifth plate 15. and the second reference capacitor between the eighth plate 22 and the sixth plate 16. ; Real-time capacitance monitoring steps: During the monitoring process, the real-time capacitance values ​​between the seventh plate 21 and the first plate 11, second plate 12, third plate 13, fourth plate 14, and fifth plate 15 are measured using a capacitance meter. , , , , And the real-time capacitance value between the eighth plate 22 and the sixth plate 16. ; Axial displacement calculation steps: based on real-time capacitance value With the second reference capacitor Based on the relationship between the changes, calculate the relative displacement ΔZ between the first flange 1 and the second flange 2 along the axial direction; In-plane displacement determination and calculation steps: based on real-time capacitance value , , , Whether the value exceeds a preset sensitivity threshold determines the direction quadrant of the in-plane displacement; based on real-time capacitance values. , , , Capacitance values ​​greater than the threshold, real-time capacitance values Given the side length L, calculate the relative displacements ΔX and ΔY between the first flange 1 and the second flange 2 in two orthogonal directions within the plane.

[0033] (1) In the axial displacement calculation step, the formula for calculating ΔZ is:

[0034] in, is the dielectric constant of the capacitor.

[0035] For example, when reference plane B displaces relative to reference plane A in the z-direction, the relative displacement in the z-direction is first determined by measuring the change in C68. An increase in C68 indicates displacement in the -z-direction, while a decrease in C68 indicates displacement in the z-direction. The capacitance in the z-direction before displacement is... capacitance in the z-direction after displacement ,but

[0036] (2) Calculate the relative displacements ΔX and ΔY between the first flange 1 and the second flange 2 in two orthogonal directions within the plane, specifically:

[0037] In the formula and These are the real-time capacitance values ​​between the first, second, third, or fourth plate and the seventh plate, which are related to the displacement direction. This is the real-time capacitance value between the fifth and seventh plates.

[0038] For example, if the capacitance change between the seventh plate 21 and the first plate 11 and the second plate 12 is detected, it indicates that the two reference planes have undergone relative displacement in the x and y directions. △x>0, △y>0,

[0039]

[0040]

[0041] Simultaneous solution

[0042] Thus, Δx, Δy, and Δz can all be obtained by measuring the capacitance between the electrodes. Ultimately, the displacement (Δx, Δy, Δz) of reference plane B relative to reference plane A can be measured, with the direction being its vector sum and direction. Similarly, regardless of the direction in which reference plane B moves relative to reference plane A, the magnitude and direction of its displacement can be determined by measuring the capacitance of the capacitor.

[0043] Finally, the calculated Δx, Δy, and Δz are combined into a three-dimensional displacement vector, which is then displayed, stored, or transmitted. The magnitude of the three-dimensional displacement vector or the absolute value of any component in any direction is compared with a preset safety threshold. If the threshold is exceeded, an alarm signal is generated.

[0044] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A flange relative displacement measuring device based on the principle of capacitance ranging, characterized in that, include: First flange (1), the lower end face of the first flange (1) is the first reference surface; second flange (2), the upper end face of the second flange (2) is the second reference surface opposite to the first reference surface; The first set of capacitor plates is installed in the four corner areas of the first reference surface of the first flange (1). The first set of capacitor plates includes a first plate (11), a second plate (12), a third plate (13), a fourth plate (14), a fifth plate (15), and a sixth plate (16). The second set of capacitor plates is installed in the four corner areas of the second reference surface of the second flange (2). The second set of capacitor plates includes a seventh plate (21) and an eighth plate (22). When the first flange (1) and the second flange (2) are fastened by the bolts (3) and nuts (4), the first set of capacitor plates and the second set of capacitor plates are positioned opposite each other in the vertical direction. The capacitance measuring instrument is electrically connected to each plate in the first group of capacitor plates and each plate in the second group of capacitor plates via wires, and is used to measure the capacitance value between selected plate pairs in the first group of capacitor plates and the second group of capacitor plates. The data communication module is used to send the capacitance value between the first group of capacitor plates and the selected plate pair in the second group of capacitor plates, which is collected by the capacitance measuring instrument, to the computer. Computers are used to calculate and display real-time and historical displacement data and alarm information.

2. The flange relative displacement measuring device based on the capacitance ranging principle according to claim 1, characterized in that, The fifth electrode plate (15) is located in the area enclosed by the first electrode plate (11), the second electrode plate (12), the third electrode plate (13) and the fourth electrode plate (14), and the four sides of the fifth electrode plate (15) coincide with one side of the first electrode plate (11), the second electrode plate (12), the third electrode plate (13) and the fourth electrode plate (14); The vertical projection of the seventh electrode plate (21) onto the first reference plane is completely or partially overlapped with the fifth electrode plate (15); The vertical projection of the eighth pole plate (22) onto the first reference plane is entirely within the projection range of the sixth pole plate (16).

3. A flange relative displacement measuring device based on the capacitance ranging principle according to claim 1 or 2, characterized in that, The first electrode plate (11), the second electrode plate (12), the third electrode plate (13), the fourth electrode plate (14), the fifth electrode plate (15), the seventh electrode plate (21), and the eighth electrode plate (22) are square electrode plates with equal side lengths, and their side lengths are L; the sixth electrode plate (16) is a square electrode plate with a side length of 3L.

4. The flange relative displacement measuring device based on the capacitance ranging principle according to claim 2, characterized in that, The first electrode plate (11), the second electrode plate (12), the third electrode plate (13), and the fourth electrode plate (14) are centrally symmetrically distributed around the fifth electrode plate (15).

5. The flange relative displacement measuring device based on the capacitance ranging principle according to claim 1, characterized in that, The capacitance measuring instrument is a multi-channel capacitance measuring instrument that measures the capacitance value between the seventh plate (21) and the first plate (11), the second plate (12), the third plate (13), the fourth plate (14), and the fifth plate (15), as well as the capacitance value between the eighth plate (22) and the sixth plate (16), either synchronously or at different times.

6. The flange relative displacement measuring device based on the capacitance ranging principle according to claim 1, characterized in that, The first capacitor plate group and the second capacitor plate group are formed by fabricating conductive patterns on a flexible insulating substrate or a rigid insulating substrate, and are fixed to the first reference plane and the second reference plane by means of bonding, snapping or mechanical fastening.

7. A measurement method for a flange relative displacement measuring device based on the capacitance ranging principle as described in any one of claims 1-6, characterized in that, include: Reference capacitance acquisition steps: When the first flange (1) and the second flange (2) are in the initial tightened state, the reference capacitance value is measured and recorded by the capacitance measuring instrument, including at least the first reference capacitance between the seventh plate (21) and the fifth plate (15). and the second reference capacitor between the eighth plate (22) and the sixth plate (16). ; Real-time capacitance monitoring steps: During the monitoring process, the capacitance values ​​between the seventh plate (17) and the first plate (11), second plate (12), third plate (13), fourth plate (14), and fifth plate (15) are measured in real time using the capacitance measuring instrument. , , , , and the real-time capacitance value between the eighth electrode plate (22) and the sixth electrode plate (16). ; Axial displacement calculation steps: Based on the real-time capacitance value With the second reference capacitor Based on the relationship between the changes, calculate the relative displacement ΔZ between the first flange (1) and the second flange (2) along the axial direction; In-plane displacement determination and calculation steps: based on the real-time capacitance value , , , Whether the value exceeds a preset sensitivity threshold is used to determine the direction quadrant of the in-plane displacement; based on the real-time capacitance value... , , , The capacitance value greater than the threshold, the real-time capacitance value And the side length L, calculate the relative displacement ΔX and ΔY between the first flange (1) and the second flange (2) in two orthogonal directions in the plane.

8. The measurement method according to claim 7, characterized in that, In the axial displacement calculation step, the formula for calculating ΔZ is: in, is the dielectric constant of the capacitor.

9. The measurement method according to claim 7, characterized in that, The calculation of the relative displacements ΔX and ΔY between the first flange (1) and the second flange (2) in two orthogonal directions in the plane is as follows: In the formula and These are the real-time capacitance values ​​between the first, second, third, or fourth plate and the seventh plate, respectively, which are related to the displacement direction. , , or ; This is the real-time capacitance value between the fifth and seventh plates.

10. The measurement method according to claim 7, characterized in that, It also includes displacement synthesis and output steps: synthesizing the calculated ΔX, ΔY, and ΔZ into a three-dimensional displacement vector, and then displaying, storing, or transmitting it; Warning step: Compare the magnitude of the three-dimensional displacement vector or the absolute value of its component in any direction with a preset safety threshold. If the threshold is exceeded, an alarm signal is generated.

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