Capacitive abrasive particle detection sensor based on edge enhanced coplanar electrode structure and online oil detection system

Abstract

The invention relates to the technical field of oil detection, and discloses a capacitive abrasive particle detection sensor based on an edge enhanced coplanar electrode structure and an online oil detection system, the sensor comprises a metal shielding shell, an integrated flow channel structure, an electrode substrate, a coplanar electrode and an electrode plate groove. The two coplanar electrodes adopt the same overall contour and edge enhancement structure, the coplanar electrodes are square, continuous and periodic groove structures are respectively formed on four edges of the coplanar electrodes, and the groove structures on the edges are the same. According to the invention, electrode design of a coplanar arrangement structure is adopted, an enhanced edge structure is introduced by considering an electrode edge effect, and an edge capacitance correction term is constructed for edge electric field correction, so that the problems of non-uniform electric field and insufficient detection precision caused by the fact that a traditional coaxial capacitance sensor does not consider the electrode edge effect are solved; electric field enhancement of the central area of the flow channel and high-sensitivity monitoring of the whole watershed are achieved, the abrasive particle detection precision and the sensor space sensitivity are improved, and the detection precision of the sensor is improved.

Description

Technical Field

[0001] This invention relates to the field of engine oil detection technology, and more specifically to a capacitive abrasive detection sensor and online oil detection system based on an edge-enhanced coplanar electrode structure, for online abrasive detection and health status assessment of aero-engine lubricating oil systems. Background Technology

[0002] The lubrication system is an indispensable critical system for aero engines. It carries away particles generated by wear between components through the lubrication lines, reducing friction and wear between parts, thus playing a lubricating role and extending the service life of components. The lubrication oil contains a wealth of information about faults and failures of rotating engine parts, requiring close monitoring of abrasive particles in the lubrication oil to achieve life prediction.

[0003] Currently, engine lubricating oil wear detection technologies include offline detection and online monitoring. Offline wear detection technology is relatively mature, and its main methods include spectral analysis, ferrography, and scanning electron microscopy. However, it requires long-term monitoring and analysis of the oil, which greatly increases the workload of component wear monitoring and results in a long cycle for obtaining wear condition information.

[0004] Currently, online monitoring methods can be broadly categorized into two types: electromagnetic methods and non-electromagnetic methods. Non-electromagnetic methods include optical detection methods, acoustic detection methods, and energy detection methods.

[0005] Electromagnetic detection methods include various types such as magnetic methods, resistance methods, and capacitance methods. Within electromagnetic methods, magnetic sensors can be divided into static magnetic and electromagnetic types. The principle is that when ferromagnetic abrasive particles pass through the sensor, the magnetic flux changes, and the sensor monitors this change in magnetic flux. Static magnetic sensors have high sensitivity but cannot detect diamagnetic metal abrasive particles; electromagnetic sensors can distinguish between ferromagnetic and non-ferromagnetic metal abrasive particles, but their sensitivity is generally lower and they cannot detect non-metallic abrasive particles.

[0006] Capacitive abrasive particle detection is a commonly used method. It utilizes the difference in dielectric constant between oil and particles. When an abrasive particle passes through the electrode gap, the capacitance value changes instantaneously, and the particle is detected by measuring the capacitance disturbance. Capacitive abrasive particle sensors have high sensitivity and can detect non-metallic abrasive particles. However, traditional coaxial capacitive abrasive particle sensors do not consider the edge effect of the electrodes, resulting in insufficient acquisition of the electric field in the flow channel. When the distance between the electrode plates decreases, it causes an electric field distortion effect at the electrode edges, leading to insufficient monitoring sensitivity in the center of the flow channel, poor electric field uniformity, and weak abrasive particle response signal, thus affecting the system's detection accuracy. Summary of the Invention

[0007] Given that existing coaxial capacitive sensors do not consider the non-uniform electric field and insufficient detection accuracy caused by electrode edge effects, the present invention aims to provide a capacitive abrasive detection sensor and online oil detection system based on an edge-enhanced coplanar electrode structure. Based on the coplanar electrode design and edge enhancement, edge electric field correction is achieved, enhancing the electric field in the central region of the flow channel and the detection response sensitivity across the entire flow domain, thereby improving the spatial sensitivity and detection accuracy of the sensor for abrasive detection.

[0008] According to a first aspect of the present invention, a capacitive abrasive particle detection sensor based on an edge-enhanced coplanar electrode structure is provided, comprising:

[0009] A metal shielding housing, wherein a first opening and a second opening are respectively provided on opposite sides of the metal shielding housing;

[0010] The integrated flow channel structure includes a flow channel portion and an electrode mounting portion, both located within the inner cavity defined by the metal shielding shell. The flow channel portion is located between the first opening and the second opening, so that the first opening, the integrated flow channel structure, and the second opening form a through flow channel to allow the oil to be tested to pass through.

[0011] A metal electrode module is provided in the electrode mounting part of the integrated flow channel structure and is isolated from the through flow channel;

[0012] The metal electrode module includes an electrode substrate, coplanar electrodes, and an electrode plate groove. Two coplanar electrodes are fixed to one side surface of the electrode substrate and spaced apart. The opposite side surface of the electrode substrate is fixed to the electrode plate groove, so that the electrode substrate and the coplanar electrodes are fixed together inside the electrode plate groove and enclosed and installed in the electrode mounting part.

[0013] Furthermore, the two coplanar electrodes adopt the same overall cross-sectional profile and edge reinforcement structure. Each coplanar electrode has a square overall cross-sectional profile and forms a continuous periodic groove structure on each of the four edges. The groove structure on each edge is the same.

[0014] The outline shape of the groove structure is one of V-shape, arc shape, square shape, and trapezoid.

[0015] The total capacitance of the capacitive abrasive particle detection sensor is [not specified]. From the main capacitor and edge capacitance Addition constitutes:

[0016] = + ;

[0017] ;

[0018] in, This indicates the introduction of an electric field distortion factor. The capacitance per unit length, where L represents the total length of the groove profile curve of the coplanar electrode with edge reinforcement structure.

[0019] Wherein, the edge capacitor The average radius of curvature of the electrode profile edge is set based on the coplanar electrode. With electrode shape factor Decide:

[0020] ;

[0021] in, The vacuum relative permittivity, Let be the perimeter of the coplanar electrodes. The effective dielectric constant;

[0022] ;

[0023] In the formula, , These represent the relative permittivity of the upper and lower dielectric layers located on opposite sides of the coplanar electrodes, respectively. The lubricating oil and abrasive particles in the flow channel constitute the upper dielectric layer, while the lower dielectric layer is the electrode substrate.

[0024] ;

[0025] ;

[0026] In the formula, This refers to the number of abrasive grains per unit volume. The volume of a single abrasive grain. This refers to the total volume per unit volume, i.e., the volume of the flow channel;

[0027] ;

[0028] In the formula, Let be the local radius of curvature at the curve. The length of the contour path;

[0029] ;

[0030] In the formula, This is the proportionality coefficient. , To optimize the edge capacitance value of the sensor, This is the edge capacitance value of the original electrode sensor.

[0031] Wherein, the main capacitor Set to be based on electric field distortion factor The elliptic integrals of the modulus k and the complementary modulus k′ determined by the coplanar electrode with edge reinforcement structure are as follows:

[0032] ;

[0033] In the formula, and Let the elliptic integrals corresponding to the modulus k and the complement k′ be represented as follows:

[0034] ;

[0035] ;

[0036] in, , ;

[0037] In the formula, w represents the width of the coplanar electrode, and s represents the gap between the coplanar electrodes;

[0038] electric field distortion factor Represented as:

[0039]

[0040] In the formula, h is the distance between the abrasive grain and the electrode. , These are empirical parameters, determined by fitting a dataset of distance and capacitance changes using a nonlinear least squares method.

[0041] According to a second aspect of the present invention, an online oil detection system suitable for aircraft engine oil detection is provided, comprising:

[0042] The aforementioned capacitive abrasive particle detection sensor based on an edge-enhanced coplanar electrode structure;

[0043] A digital-to-digital converter module is electrically connected to the capacitive abrasive particle detection sensor to perform analog-to-digital conversion;

[0044] The host computer connects to the digital capacitor converter module and receives electrical signals. It then analyzes the signals through a signal processing program to determine the presence and type of abrasive particles in the oil.

[0045] The capacitive abrasive particle detection sensor based on an edge-enhanced coplanar electrode structure described in the above embodiments of the present invention uses the capacitive detection principle to realize online detection of aero-engine oil. It adopts a coplanar electrode design and considers the electrode edge effect to introduce an enhanced edge structure. Furthermore, it constructs an edge capacitance correction term to correct the edge electric field, which solves the problem of non-uniform electric field and insufficient detection accuracy caused by the failure to consider the electrode edge effect in traditional coaxial capacitive sensors. Through the design of the present invention, it realizes electric field enhancement in the flow channel center region and high-sensitivity monitoring of the entire flow domain, improves the abrasive particle detection accuracy and sensor spatial sensitivity, and enhances the sensor's detection accuracy.

[0046] It should be understood that all combinations of the foregoing concepts and the additional concepts described in more detail below may be considered part of the inventive subject matter of this disclosure, provided that such concepts do not contradict each other. Furthermore, all combinations of the claimed subject matter are considered part of the inventive subject matter of this disclosure.

[0047] The foregoing and other aspects, embodiments, and features of the teachings of the present invention will be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the invention, such as features and / or beneficial effects of exemplary embodiments, will become apparent from the following description or may be learned through practice of specific embodiments according to the teachings of the present invention. Attached Figure Description

[0048] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in the various figures may be denoted by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the invention will now be described by way of example and with reference to the accompanying drawings.

[0049] Figure 1 This is a schematic diagram of the overall structure of a capacitive abrasive detection sensor based on an edge-enhanced coplanar electrode structure according to an embodiment of the present invention.

[0050] Figure 2 This is a half-section structural schematic diagram of a capacitive abrasive detection sensor based on an edge-enhanced coplanar electrode structure according to an embodiment of the present invention.

[0051] Figure 3 This is a schematic diagram of the structure of a metal electrode module according to an embodiment of the present invention.

[0052] Figure 4A , 4B These are perspective and top views of the electrode plate groove according to an embodiment of the present invention.

[0053] Figure 5 This is a schematic diagram of the structure of a coplanar electrode according to an embodiment of the present invention.

[0054] Figure 6 This is a schematic diagram of an online oil detection system for aircraft engine oil detection according to an embodiment of the present invention.

[0055] Figure 7 This is a schematic diagram of a specific example of an online oil detection system for aircraft engine oil detection according to an embodiment of the present invention.

[0056] Figure 8 This is a graph showing real-time abrasive particle detection data from an online oil detection system according to an embodiment of the present invention.

[0057] Figure 9 This is a graph showing real-time abrasive particle detection data from an online oil detection system according to an embodiment of the present invention. Figure 10 This is a schematic diagram illustrating the repeatability of abrasive particle detection in an online oil detection system according to an embodiment of the present invention.

[0058] The definitions of the labels in the attached diagram are as follows:

[0059] Metal shielding housing 10, first opening 11, second opening 12, wiring port 13;

[0060] Integrated flow channel structure 20, flow channel section 21, electrode mounting section 22;

[0061] Electrode substrate 31, coplanar electrode 32, coplanar electrode fixing hole 32A, electrode plate groove 33, wire through hole 33A, substrate fixing hole 33B;

[0062] Seal 40. Detailed Implementation

[0063] To better understand the technical content of the present invention, specific embodiments are described below in conjunction with the accompanying drawings.

[0064] Various aspects of the invention are described in this disclosure with reference to the accompanying drawings, which illustrate numerous illustrative embodiments. The embodiments of this disclosure are not necessarily intended to encompass all aspects of the invention. It should be understood that the various concepts and embodiments described above, as well as those described in more detail below, can be implemented in any of many ways, because the concepts and embodiments disclosed herein are not limited to any particular implementation. Furthermore, some aspects of the invention disclosed may be used alone or in any suitable combination with other aspects of the invention disclosed.

[0065] {Example 1}

[0066] Combination Figures 1-5The example shown is a capacitive abrasive detection sensor 100 based on an edge-enhanced coplanar electrode structure disclosed in the present invention, which includes a metal shielding housing 10, an integrated flow channel structure 20, and a metal electrode module.

[0067] Combination Figure 1 As shown, the metal shielding housing 10 constitutes the outer shell of the entire sensor, providing overall protection and shielding. The metal shielding housing 10 can be made of aluminum alloy.

[0068] The metal shielding housing 10 has a first opening 11 and a second opening 12 on opposite sides, which are designed with the same shape and size and are located at the center of both sides.

[0069] Combination Figure 1 As shown, the integrated flow channel structure 20 is provided with a flow channel portion 21 and an electrode mounting portion 22, both of which are located within the inner cavity defined by the metal shielding housing 10.

[0070] The flow channel 21 is located between the first opening 11 and the second opening 12, so that the first opening 11, the flow channel 21 of the integrated flow channel structure 20 and the second opening 12 form a through flow channel to allow the oil to be tested to pass through.

[0071] The metal electrode module has an electrode mounting section 22 located in the integrated flow channel structure 20 and isolated from the through flow channel. It should be understood that the electrode mounting section 22 and the flow channel section 21 are kept isolated from each other.

[0072] like Figure 1 In the example shown, the metal electrode module includes an electrode substrate 31, coplanar electrodes 32, and an electrode plate groove 33. The two coplanar electrodes 32 are fixed to one side surface of the electrode substrate 31 and spaced apart. The opposite side surface of the electrode substrate 31 is fixed to the electrode plate groove 33, so that the electrode substrate 31 and the coplanar electrodes 32 are fixed together inside the electrode plate groove 33 and enclosed and installed in the electrode mounting part 22.

[0073] Combination Figure 1 as well as Figure 5 As shown, the two coplanar electrodes 32 adopt the same overall cross-sectional profile and edge reinforcement structure. Each coplanar electrode 32 has a square overall cross-sectional profile and forms a continuous periodic groove structure on each of the four edges. The groove structure on each edge is the same.

[0074] Among them, the electrode substrate 31 is an insulating material, and it can be made of insulating materials such as acrylic sheets.

[0075] The coplanar electrode 32 is a copper electrode, such as an electrode sheet made of copper or brass. The electrode plate groove 33 is an insulating groove, made of insulating materials such as acrylic sheets.

[0076] like Figure 5 As shown, the outline shape of the groove structure adopts one of the following: V-shape, arc shape, square shape, and trapezoid.

[0077] Preferably, the integrated flow channel structure 20 is provided with sealing elements 40, such as sealing rings, on its edges facing the first opening 11 and the second opening 12, for sealing and isolation between the integrated flow channel structure 20 and the metal shielding housing 10.

[0078] like Figure 1 As shown, wire through holes 33A are provided on both sides of the electrode plate groove 33 for placing wires and connecting the coplanar electrode 32 to the interface of the external detection device through the wires.

[0079] The metal shielding housing 10 is provided with a wiring port 13, which is connected to a wire and used to output an electrical signal to an external detection device.

[0080] Combination Figure 1 The design of the coplanar electrode capacitive sensor structure shown uses a dimensionless modulus k to quantify the influence of the coplanar electrode geometry on the electric field distribution. In conformal transformation, the modulus k maps the three-dimensional electric field distribution of the coplanar electrode capacitive sensor onto a simplified plane, allowing the capacitance value to be analytically solved using elliptic integrals.

[0081] Based on the geometric design of the coplanar electrodes, the module k is defined as follows:

[0082] ;

[0083] In the formula: w is the width of the coplanar electrode; s is the gap between the two coplanar electrodes.

[0084] When both s and w are known, the modulus k can be simplified to:

[0085] ;

[0086] In an embodiment of the present invention, a modulus k′ of edge-enhanced coplanar electrodes is constructed as a supplementary correction to the modulus k. The modulus k′ is used to correct the distortion of the electric field under non-ideal conditions. Especially when the electrode edge effect is significant, the effect of the modulus k′ on the capacitance calculation cannot be ignored.

[0087] In an embodiment of the present invention, the compensation modulus k′ is defined as:

[0088] ;

[0089] Therefore, the complement k′ and the modulus k both participate in the elliptic integral. and The calculation is used to calculate Figure 1 The sensor design shown includes a unit length capacitance. .

[0090] First type of complete elliptic integral Defined as:

[0091]

[0092] For coplanar electrodes, capacitance per unit length The calculation is as follows:

[0093]

[0094] in, The vacuum relative permittivity, is the relative permittivity of the medium.

[0095] Combination Figure 1 As shown, when lubricating oil fills the flow channel space, its relative permittivity is... The relative permittivity of the abrasive particles in the lubricating oil within the flow channel is: The volume fraction is The relative permittivity of the electrode substrate with coplanar electrodes is: Abrasive particles mixed in lubricating oil form a mixed medium, whose equivalent relative permittivity... It can be calculated using the Maxwell-Garnett equation:

[0096] ;

[0097] ;

[0098] in, This refers to the number of abrasive grains per unit volume. The volume of a single abrasive grain. The total volume per unit volume is the volume of the flow channel.

[0099] Furthermore, regarding the issue of composite dielectrics, in embodiments of the present invention, they are divided into an upper dielectric layer and a lower dielectric layer. The upper dielectric layer comprises a mixture of lubricating oil and abrasive particles, and the lower dielectric layer is an electrode substrate. The relative permittivity of the upper and lower dielectric layers is defined as follows: , .

[0100] Therefore, the sensor capacitance value can be further expressed as:

[0101] ;

[0102] When there is a certain distance h between the abrasive grains and the coplanar electrode, the local influence of the abrasive grains on the electric field distribution of the entire flow channel space is further corrected.

[0103] In an embodiment of the present invention, an electric field distortion factor is introduced. :

[0104]

[0105] in, This indicates the distance between the abrasive grains and the coplanar electrode. , As empirical parameters, their values ​​can be determined by establishing a dataset of distance and capacitance changes and fitting it using the nonlinear least squares method.

[0106] As an optional implementation method, empirical parameters , The determination process is as follows:

[0107] First, obtain the dataset. ,in Let be the distance between the abrasive grain and the electrode at the i-th simulation data point. This represents the corresponding capacitance change factor. Next, we construct the objective function:

[0108]

[0109] The goal is to minimize the sum of squared residuals. ,Right now ;

[0110] The Levenberg-Marquardt algorithm was chosen for solving the problem. The algorithm was implemented in Python, and the fit of the fitted curve to the data was observed to verify the fitting effect. After successful fitting, the empirical parameter values ​​were recorded. , , as well as its applicable scope and error range.

[0111] Therefore, in embodiments of the present invention, an electric field distortion factor is introduced. The corrected capacitance value is expressed as follows:

[0112] .

[0113] Furthermore, combining the capacitive sensor design with the coplanar electrodes and the edge enhancement design of the coplanar electrodes of this invention, the total capacitance of the sensor... From the main capacitor and edge capacitance Addition constitutes: = + ;

[0114] ;

[0115] in, This indicates the introduction of an electric field distortion factor. The capacitance per unit length, L represents the total length of the groove profile curve of the coplanar electrode 32 with edge reinforcement structure, that is, the total length of the single side length of the electrode for each type of electrode (including the sum of the curve length of each groove part and the straight line of the non-groove part).

[0116] On the one hand, as mentioned in the design above, the main capacitor Set to be based on electric field distortion factor The elliptic integrals of the modulus k and the complementary modulus k′ of the coplanar electrode 32 with edge reinforcement structure determine the following:

[0117] ;

[0118] In the formula, and Let the elliptic integrals corresponding to the modulus k and the complement k′ be represented as follows:

[0119] ;

[0120] ;

[0121] in, , ;

[0122] In the formula, w represents the width of the coplanar electrode, and s represents the gap between the coplanar electrodes;

[0123] electric field distortion factor Represented as:

[0124]

[0125] In the formula, h is the distance between the abrasive grain and the electrode. , These are empirical parameters, determined by fitting a dataset of distance and capacitance changes using a nonlinear least squares method.

[0126] On the other hand, edge capacitance The average radius of curvature of the electrode profile edge is set based on the coplanar electrode. (The average radius of curvature of the different groove features designed for the electrode) and electrode shape factor Decide:

[0127] ;

[0128] in, The vacuum relative permittivity, This is the perimeter of the coplanar electrode (the perimeter of the entire electrode, including the perimeter of the feature path within the groove and the perimeter of the straight edge path). The effective dielectric constant;

[0129] ;

[0130] In the formula, , These represent the relative permittivity of the upper and lower dielectric layers located on opposite sides of the coplanar electrodes, respectively. The lubricating oil and abrasive particles in the flow channel constitute the upper dielectric layer, while the lower dielectric layer is the electrode substrate.

[0131] ;

[0132] ;

[0133] In the formula, This refers to the number of abrasive grains per unit volume. The volume of a single abrasive grain. This refers to the total volume per unit volume, i.e., the volume of the flow channel;

[0134] ;

[0135] In the formula, The radius of curvature at a given point on the curve includes the radius of curvature at that point as the user moves along the groove path length s from a starting point. The length of the contour path specifically refers to the length of the overall feature curve of the groove feature.

[0136] In an embodiment of the present invention, the electrode shape factor It is the average radius of curvature of the electrode profile edge of the coplanar electrode. and proportionality coefficient What is determined by both is the measurement of the electrode geometry complexity and the capacitance enhancement effect:

[0137] ;

[0138] In the formula, This is the proportionality coefficient.

[0139] As an optional implementation method, This reflects the degree to which the electrode edge shape affects the capacitance value, where To optimize the edge capacitance value of the sensor, The original electrode sensor edge capacitance value is shown. The optimized edge capacitance value refers to the edge capacitance value of the sensor after using electrodes with different edge shapes. The original electrode is the edge capacitance value of the original electrode sensor before optimization.

[0140] Therefore, the total capacitance of the sensor is determined. Represented as:

[0141] .

[0142] {Example 2}

[0143] Combination Figure 6 As shown, the online oil detection system for aircraft engine oil detection disclosed in this invention includes: a capacitive abrasive detection sensor 100, a digital capacitance converter module (CDC) 110, and a host computer 120.

[0144] The digital capacitance converter module 110, for example using a PCAP01 chip, is electrically connected to the capacitive abrasive detection sensor 100, receives the electrical signal output from the capacitive abrasive detection sensor 100, performs analog-to-digital conversion, and sends it to the host computer 120.

[0145] The host computer 120 is connected to the digital capacitance converter module 110 and receives electrical signals. The signals are analyzed by a signal processing program to determine the presence and type of abrasive particles in the oil. For example, a Kalman filter algorithm is used to extract the peak value of the capacitance pulse, thereby determining the presence and type of abrasive particles in the oil.

[0146] As an optional implementation, when abrasive particles mixed in the lubricating oil pass through a capacitive sensor, the capacitance value fluctuates due to the entry of the abrasive particles. Since the relative permittivity of the oil differs from that of the abrasive particles, the capacitance value changes, thus determining the presence of abrasive particles. Furthermore, to distinguish different types of abrasive particles, since different abrasive particles have different relative permittivity, the peak values ​​of the signal pulses acquired by the sensor differ when different types of abrasive particles pass through, thus determining the type of abrasive particles.

[0147] In this embodiment, the relative permittivity of iron abrasive grains differs greatly from that of ceramic abrasive grains. When different abrasive grains of the same size pass through the sensor, the peak values ​​of the sensor are significantly different, thereby determining the type of abrasive grain.

[0148] In an optional embodiment of the present invention, the host computer 120 is equipped with a microcontroller for performing SPI data communication and processing electrical signal output.

[0149] During data communication, the digital capacitor converter module is connected to the host computer via a USB-UART conversion interface to achieve real-time data transmission and analysis.

[0150] This invention presents an online oil detection system based on a capacitive abrasive particle detection sensor with an edge-enhanced coplanar electrode structure. The system utilizes electrode structures of different shapes, as shown in Table 1 (parameters for different electrode configurations), Table 2 (parameter variations for different electrode configurations), and Table 3 (sensor sensitivity for different electrode configurations).

[0151] The effects of varying the size of two types of abrasive grains (iron and ceramic) and their position within the sensor's monitoring space on the sensor's response were investigated.

[0152] In the embodiments of the present invention, the study is only conducted in the vertical direction because the simulation results show that the abrasive particles have a weak response in the center of the flow channel. Therefore, the Z-axis direction (i.e., the axial direction through which the lubricating oil flows in the sensor flow channel) is the focus of the experiment, which can demonstrate whether the optimized electrode has a better capacitance response in the center of the flow channel.

[0153] The results are as follows Figure 8 , 9 The figures show the changes in peak capacitance for iron and ceramic abrasive grains, respectively. The peak values ​​in the figures indicate that the capacitance value gradually increases with the increase of the abrasive grain diameter. Combined with... Figure 8 , 9 The comparison shows that iron abrasive particles have a stronger response than ceramic abrasive particles. The sensor can detect iron abrasive particles as small as 100 micrometers, and it can also detect ceramic abrasive particles as small as 200 micrometers.

[0154] Meanwhile, comparing the simulation data and experimental data, the capacitance values ​​of iron abrasives and ceramic abrasives increased with the increase of abrasive size, which is consistent with the simulation. The capacitance value of iron abrasives increased more significantly, while the capacitance value of ceramic abrasives increased more slowly. The experimental data and simulation data are close.

[0155] By using electrodes with different configurations designed in this invention, the SVP value was reduced by 53.4% ​​(characterizing the uniformity of sensitivity distribution; the lower the value, the higher the uniformity). Furthermore, when the abrasive grains were located at different positions within the flow channel, the response intensity of the abrasive grains at mid-to-long-distance distances within the flow channel increased by 9%. Combined with... Figure 10 As shown in the figure, the experiment shows that the sensor has a repeatability coefficient of up to 0.82% and a signal drift of ±1.4%, indicating that the sensor has good stability.

[0156] Table 1 Electrode parameters of different configurations

[0157] Table 2 Variation parameters of electrode sensors with different configurations

[0158] Table 3 Sensitivity of Electrode Sensors with Different Configurations

[0159] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A capacitive abrasive particle detection sensor based on an edge-enhanced coplanar electrode structure, characterized in that, include: A metal shielding housing (10) has a first opening (11) and a second opening (12) on opposite sides. The integrated flow channel structure (20) is provided with a flow channel part (21) and an electrode mounting part (22), both of which are located within the inner cavity defined by the metal shielding shell (10). The flow channel part (21) is located between the first opening (11) and the second opening (12), so that the first opening (11), the integrated flow channel structure (20), and the second opening (12) form a through flow channel to allow the oil to be tested to pass through. The metal electrode module is provided with an electrode mounting part (22) located in the integrated flow channel structure (20) and isolated from the through flow channel; The metal electrode module includes an electrode substrate (31), coplanar electrodes (32), and an electrode plate groove (33). Two coplanar electrodes (32) are fixed to one side surface of the electrode substrate (31) and spaced apart. The opposite side surface of the electrode substrate (31) is fixed to the electrode plate groove (33), so that the electrode substrate (31) and the coplanar electrodes (32) are fixed together inside the electrode plate groove (33) and enclosed and installed to the electrode mounting part (22). Furthermore, the two coplanar electrodes (32) adopt the same overall cross-sectional profile and edge reinforcement structure. Each coplanar electrode (32) has a square overall cross-sectional profile and forms a continuous periodic groove structure on each of the four edges. The groove structure on each edge is the same.

2. The capacitive abrasive particle detection sensor based on an edge-enhanced coplanar electrode structure according to claim 1, characterized in that, The outline shape of the groove structure adopts one of the following: V-shape, arc shape, square shape, trapezoidal shape.

3. The capacitive abrasive particle detection sensor based on an edge-enhanced coplanar electrode structure according to claim 1, characterized in that, The electrode mounting portion (22) and the flow channel portion (21) are kept isolated from each other.

4. The capacitive abrasive particle detection sensor based on an edge-enhanced coplanar electrode structure according to claim 1, characterized in that, The integrated flow channel structure (20) has sealing elements (40) on its edges facing the first opening (11) and the second opening (12) respectively, for sealing and isolation between the integrated flow channel structure (20) and the metal shielding shell (10).

5. The capacitive abrasive particle detection sensor based on an edge-enhanced coplanar electrode structure according to claim 1, characterized in that, The electrode substrate (31) is an insulating material; The coplanar electrode (32) is a copper electrode; The electrode plate groove (33) is an insulating groove.

6. The capacitive abrasive particle detection sensor based on an edge-enhanced coplanar electrode structure according to claim 1, characterized in that, The electrode plate groove (33) is provided with wire through holes (33A) on both sides for placing wires and connecting the coplanar electrode (32) to the external detection device interface through the wires; The metal shielding housing (10) is provided with a wiring port (13) for connecting to the wire and for outputting electrical signals to an external detection device.

7. The capacitive abrasive particle detection sensor based on an edge-enhanced coplanar electrode structure according to any one of claims 1-6, characterized in that, The total capacitance of the capacitive abrasive particle detection sensor From the main capacitor and edge capacitance Addition constitutes: = + ； ； in, This indicates the introduction of an electric field distortion factor. The capacitance per unit length, L represents the total length of the groove profile curve of the coplanar electrode (32) with edge reinforcement structure.

8. The capacitive abrasive particle detection sensor based on an edge-enhanced coplanar electrode structure according to claim 7, characterized in that, The edge capacitor The average radius of curvature of the electrode profile edge is set based on the coplanar electrode. With electrode shape factor Decide: ； in, The vacuum relative permittivity, Let be the perimeter of the coplanar electrodes. The effective dielectric constant; ； In the formula, , These represent the relative permittivity of the upper and lower dielectric layers located on opposite sides of the coplanar electrodes, respectively. The lubricating oil and abrasive particles in the flow channel constitute the upper dielectric layer, while the lower dielectric layer is the electrode substrate. ； ； In the formula, This refers to the number of abrasive grains per unit volume. The volume of a single abrasive grain. This refers to the total volume per unit volume, i.e., the volume of the flow channel; ； In the formula, Let be the local radius of curvature at the curve. The length of the contour path; ； In the formula, This is the proportionality coefficient. , To optimize the edge capacitance value of the sensor, This is the edge capacitance value of the original electrode sensor.

9. The capacitive abrasive particle detection sensor based on an edge-enhanced coplanar electrode structure according to claim 8, characterized in that, The main capacitor Set to be based on electric field distortion factor The elliptic integrals of the modulus k and the complementary modulus k′ determined by the coplanar electrode (32) with edge reinforcement structure are: ; In the formula, and Let the elliptic integrals corresponding to the modulus k and the complement k′ be represented as follows: ； ； in, , ; In the formula, w represents the width of the coplanar electrode, and s represents the gap between the coplanar electrodes; electric field distortion factor Represented as: ； In the formula, h is the distance between the abrasive grain and the electrode. , These are empirical parameters, determined by fitting a dataset of distance and capacitance changes using a nonlinear least squares method.

10. An online oil detection system suitable for aircraft engine oil detection, characterized in that, include: Capacitive abrasive detection sensor (100) based on edge-enhanced coplanar electrode structure as described in any one of claims 1-9. The digital-to-digital converter module (110) is electrically connected to the capacitive abrasive detection sensor to perform analog-to-digital conversion; The host computer (120) is connected to the digital capacitor converter module (110) and receives electrical signals. It analyzes the signals through a signal processing program to determine the presence and type of abrasive particles in the oil.

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