Abrasive particle sensing device and abrasive particle detection method based on differential coaxial capacitor

Abstract

The invention discloses an abrasive particle sensing device based on a differential coaxial capacitor and an abrasive particle detection method. The device comprises an annular metal electrode, a cylindrical metal electrode and a flange structure, wherein the annular metal electrode and the cylindrical metal electrode are used for generating an electrostatic field, and the flange structure is used for supporting and fixing. Wherein the flange structure comprises a left flange, a right flange and a flange connecting piece; the cylindrical metal electrode is arranged at the center of the lubricating oil flow channel of the sensing device and is fixed through a flange structure; the annular metal electrodes are arranged on the inner side boss of the left flange and the inner side boss of the right flange, and the inner side boss of the left flange and the inner side boss of the right flange are embedded into the flange connecting piece; through the integrated differential monitoring structure, crosstalk between the electrodes is reduced, the sensitivity of the sensing device is improved, and therefore the accuracy of metal abrasive particle detection is improved; and compared with the existing sensor design, the processing difficulty is low, the structural reliability is high, and the circuit design cost is low.

Description

Technical Field

[0001] The invention relates to the technical field of online engine monitoring, and in particular to an abrasive particle sensing device and an abrasive particle detection method based on a differential coaxial capacitor. Background Art

[0002] The lubrication system is an indispensable and key component of the engine. It significantly extends the service life of the entire system and its various components by reducing friction and wear. As the engine runs, the performance of the lubrication system will fluctuate due to changes in the equipment status. In particular, as the use time of the engine's rotating parts increases, friction and wear will cause the surface material of the parts to fall off and form abrasive particles.

[0003] At present, there are two main methods used for engine oil wear particle detection technology at home and abroad: offline detection and online monitoring. The development of offline wear particle detection technology has been relatively mature, and its main methods include spectral analysis, iron spectrum analysis and scanning electron microscopy. The offline detection method has high sensitivity, but its equipment operation process is complicated and requires professional experimental personnel. Therefore, the accuracy of its test results depends to a large extent on the personal experience and professional level of the experimenter.

[0004] Online monitoring methods include optical, acoustic, magnetic and capacitive methods. Among them, the optical method detection sensor equipment is large, complex and expensive. The acoustic method detection sensor has average sensitivity, and the equipment structure is complex, and the sensitivity is easily affected by pipeline vibration. The magnetic method detection sensor includes static magnetometry and electromagnetic type. Among them, static magnetometry sensors cannot detect antimagnetic metal abrasive particles; electromagnetic sensors cannot detect non-metallic abrasive particles; the sensitivity of the capacitive method detection sensor is affected by the quality of the lubricating oil. Therefore, a metal abrasive particle detection device with high sensitivity, simple structure, low cost and high detection accuracy is urgently needed.

[0005] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0006] The object of the present invention is to provide a metal abrasive particle sensing device with high sensitivity, simple structure, low cost and high detection accuracy.

[0007] The present invention provides an abrasive particle sensing device based on differential coaxial capacitor, comprising:

[0008] A circular metal electrode and a cylindrical metal electrode for generating an electrostatic field, and a flange structure for supporting fixation; wherein,

[0009] The flange structure comprises a left flange, a right flange and a flange connector;

[0010] The cylindrical metal electrode is arranged at the exact center of the lubricating oil flow channel of the sensor device and is fixed by the flange structure; the annular metal electrode is arranged on the inner boss of the left flange and the inner boss of the right flange, and the inner boss of the left flange and the inner boss of the right flange are embedded in the flange connector.

[0011] Preferably, in an embodiment of the present invention, there are two circular ring-shaped metal electrodes.

[0012] Preferably, in the embodiment of the present invention, a groove is provided at the center of the left flange and the center of the right flange; and a wire hole is provided on the support column of the right flange.

[0013] Preferably, in the embodiment of the present invention,

[0014] The flange connector is provided with grooves at the center and on both sides; the groove at the center of the flange connector is used to install a metal isolation plate; the grooves on both sides of the flange connector are respectively used to embed the inner boss of the left flange and the inner boss of the right flange.

[0015] Preferably, in the embodiment of the present invention, the metal isolation plates are semicircular in shape and there are two of them.

[0016] Preferably, in an embodiment of the present invention, the metal isolation plate and the flange connector are provided with wire holes.

[0017] Preferably, in the embodiment of the present invention, it also includes:

[0018] A metal protective cover for electromagnetic shielding; the metal protective cover is a single-layer metal shielding layer, which is threadedly connected by a left shell and a right shell.

[0019] In another aspect of the present invention, a wear particle detection method is also provided, which is used in the wear particle sensing device based on differential coaxial capacitance as described above, comprising the steps of:

[0020] S11, preset the level of the annular electrode; ground the cylindrical electrode; and energize the abrasive particle sensing device according to the preset level to obtain two capacitance signal data;

[0021] S12, calculating the mean and difference according to the capacitance signal data, and performing zero point shift according to the difference; the difference is the difference between the value of each capacitance signal and the mean;

[0022] S13, filtering the two capacitance signals after zero point shift;

[0023] S14, performing differential calculation and threshold extraction on the two capacitance signal data after filtering to obtain a capacitance pulse signal peak value;

[0024] S15, obtaining abrasive particle detection results according to the peak value of the capacitance pulse signal and the abrasive particle size parameters.

[0025] Preferably, in an embodiment of the present invention, the filtering process of the two capacitance signals after zero point shifting includes:

[0026] Kalman filtering is used to reduce the noise signal.

[0027] Preferably, in an embodiment of the present invention, performing differential calculation on the two capacitance signal data after filtering includes:

[0028] c i =αA i +βA′ i

[0029] In the formula, A i , A′ i They are two capacitance change arrays respectively; α and β are compensation coefficients, and the value of β is a negative number.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] In the present invention, the crosstalk between electrodes is reduced through an integrated differential monitoring structure, the sensitivity of the sensing device is improved, and thus the accuracy of metal abrasive particle detection is also improved; and compared with the existing sensor design, the processing difficulty is low, the structural reliability is high and the circuit design cost is low.

[0032] Furthermore, the present invention reduces the noise of circuit interference through differential detection and improves the signal-to-noise ratio.

[0033] In addition, the present invention effectively reduces the equivalent spacing between the plates through the coaxial capacitor design, and further improves the sensitivity of the sensor device.

[0034] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, and to make the above and other purposes, technical features and advantages of the present invention easier to understand, one or more preferred embodiments are listed below and described in detail with the accompanying drawings as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1It is a structural schematic diagram of the wear particle sensing device based on differential coaxial capacitor described in the present invention;

[0037] Figure 2 It is a structural schematic diagram of the left flange and the right flange in the present invention;

[0038] Figure 3 It is a structural schematic diagram of the flange connection member described in the present invention;

[0039] Figure 4 is a schematic diagram of an oil detection system of an abrasive particle sensing device based on a differential coaxial capacitor according to the present invention;

[0040] Figure 5 is a schematic diagram of the internal structure of the signal processing described in the present invention;

[0041] Figure 6 This is a schematic diagram of the circuit design of the capacitance monitoring chip of the CDC module described in the present invention;

[0042] Figure 7 This is a schematic diagram of the controller chip circuit design of the CDC module described in the present invention;

[0043] Figure 8 This is a real-time detection data diagram of abrasive particles in the present invention;

[0044] Fig. 9 It is a schematic diagram of the abrasive particle detection range described in the present invention;

[0045] Fig.10 1 is a step diagram of the wear particle detection method described in the present invention. DETAILED DESCRIPTION

[0046] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific implementation modes.

[0047] Unless explicitly stated otherwise, throughout the specification and claims, the term “comprise” or variations such as “include” or “comprising”, etc., will be understood to include the stated elements or components but not to exclude other elements or components.

[0048] In this document, the terms "first", "second", etc. are used to distinguish two different elements or parts, and are not used to limit a specific position or relative relationship. In other words, in some embodiments, the terms "first", "second", etc. can also be interchangeable.

[0049] Embodiment 1

[0050] The accuracy of wear particle detection is improved by using a simple and low-cost metal wear particle sensor device, such as Figure 1 As shown, an embodiment of the present invention provides an abrasive particle sensing device based on a differential coaxial capacitor, comprising:

[0051] Circular metal electrodes 1, 2 and cylindrical metal electrode 3 for generating an electrostatic field, and a flange structure for supporting fixation; wherein,

[0052] The flange structure includes a left flange 4, a right flange 5 and a flange connector 6;

[0053] The cylindrical metal electrode 3 is arranged at the center of the lubricating oil flow channel of the abrasive sensor device and is fixed by the flange structure; the annular metal electrodes 1 and 2 are arranged on the inner boss of the left flange 4 and the inner boss of the right flange 5, and the inner boss of the left flange 4 and the inner boss of the right flange 5 are embedded in the flange connector 6.

[0054] In the embodiment of the present invention, there are two annular metal electrodes (i.e., annular metal electrode 1 and annular metal electrode 2); a groove 9 is provided at the center of the left flange 4 and the center of the right flange 5, and the groove 9 is used to fix the cylindrical metal electrode 3; and a cylindrical wire hole 8 is provided on the support of the right flange 4 for placing the wire of the cylindrical metal electrode 3, as shown in the specific Figure 2 Schematic diagram of the structure of the left flange and the right flange shown.

[0055] Further, in the embodiment of the present invention, the structure of the flange connector 6 is as follows: Figure 3 As shown, the flange connector 6 is provided with grooves in the center and on both sides; the groove 14 in the center of the flange connector 6 is used to install the metal isolation plate; the grooves 15 and 16 on both sides of the flange connector 6 are respectively used to embed the inner boss of the left flange 4 and the inner boss of the right flange 5, so as to achieve electrode fixation and oil sealing; the metal isolation plate is composed of two semicircular metal plates 10 and 11; the metal isolation plate and the flange connector 6 are provided with wire holes 12 for placing the wires of the circular metal electrodes 1 and 2.

[0056] Preferably, in an embodiment of the present invention, it also includes: a metal protective cover 7 for electromagnetic shielding; the metal protective cover 7 is a single-layer metal shielding layer, which is threadedly connected by a left shell and a right shell, and all wires enter and exit from a threaded interface 13 left on the cylinder wall, and the shell is grounded through the wires.

[0057] In specific applications, the annular metal electrodes 1 and 2 can be made of copper material with an inner diameter of 10 mm, an outer diameter of 12 mm and a width of 2 mm; the cylindrical metal electrode 3 can be made of titanium alloy material with a radius of 1 mm and a length of 18 mm; the left flange 4, the right flange 5 and the flange connector 6 can be made of ceramic material, the flange connector 6 has an inner diameter of 8 mm and an outer diameter of 24 mm, the grooves 15 on both sides are 1 mm high and 0.7 mm deep, the center groove 14 is 1 mm wide and 7 mm deep, and the wire hole 12 has a radius of 1 mm; the outer diameter of the left flange 4 and the right flange 5 is 12 mm, the radius of the groove 9 for mounting the cylindrical metal electrode 3 is 1 mm and the depth is 5 mm, the inner boss for mounting the annular metal electrodes 1 and 2 is 2.7 mm wide and 1 mm thick, and the wire hole 8 on the right flange 4 has a diameter of 1.5 mm; the semi-circular metal isolation plates 10 and 11 can be made of copper material, and the metal shielding cover 7 can be made of nickel-iron alloy material.

[0058] To sum up, in the embodiment of the present invention, the crosstalk between electrodes is reduced through the integrated differential monitoring structure, the sensitivity of the sensing device is improved, and thus the accuracy of metal abrasive particle detection is also improved; and compared with the existing sensor design, the processing difficulty is low, the structural reliability is high and the circuit design cost is low.

[0059] Furthermore, in the embodiment of the present invention, the noise of circuit interference is reduced through differential detection, thereby improving the signal-to-noise ratio.

[0060] In addition, in the embodiment of the present invention, the coaxial capacitor design effectively reduces the equivalent spacing between the plates, and further improves the sensitivity of the sensor device.

[0061] Embodiment 2

[0062] On the basis of the first embodiment, the embodiment of the present invention further constructs an oil detection system based on a wear particle sensor device of a differential coaxial capacitor, as shown in the following example: Figure 4 As shown, including:

[0063] The sensor unit 16, the signal extraction module 17, and the host computer 18 are specifically as follows Figure 4 The signal extraction module 17 includes a CDC module 19 and a simulator 20 .

[0064] The internal structure of the signal processing in the signal extraction module 17 is as follows: Figure 5As shown; the CDC module 19 includes an 8-pin pin 21 for connecting the sensor unit 16, a 3-pin pin 22 for connecting to the power supply system, and a 4-pin pin 23 for connecting to the SWD 20-pin pin 24 of the simulator module 20, so as to upload the capacitance data and download the control program; the simulator 20 is used as a debugging and programming tool, and is connected to the host computer using the DAC interface 25. The CDC module is updated with firmware, parameter configuration, and troubleshooting is performed by manipulating the host computer software, thereby ensuring the reliability and stability of the oil detection system.

[0065] The circuit design of the CDC module, such as Figure 6 and Figure 7 As shown, Figure 6 This is the circuit design diagram of the capacitance monitoring chip of the CDC module. Figure 7 The controller chip circuit design diagram of the CDC module; the CDC module 19 uses the PCAP01 capacitance-to-digital converter chip to achieve high-precision measurement of capacitance changes, and uses the STM32F103C8T6 microcontroller as the control unit of the measurement system. Data communication between the microcontroller and the capacitance-to-digital converter chip is achieved through the SPI interface. During operation, the capacitance-to-digital converter uses the grounded measurement mode of the multi-channel capacitance sensor and is equipped with an internal parasitic capacitance and temperature error compensation algorithm to improve the stability and accuracy of the measurement.

[0066] The signal data processing program in the host computer includes two functions: signal filtering and differential calculation; the signal data processing program reads two channels of valid data from the host computer. The two channels of valid data are approximate time, and the capacitance change data containing the same wear particle information detected on the two metal outer plates under the same detection mode transmitted by the simulator 20. The pulse signal peak value is obtained through the two channels of valid data, thereby realizing wear particle detection.

[0067] In specific implementation, the oil detection system of the wear particle sensor device based on the differential coaxial capacitor includes the following steps:

[0068] (1) Connect the 3-pin pin 22 of the CDC module 20 to the USB port of the host computer 18 and access the 3.3V working voltage;

[0069] (2) Connect the VCC, SWDIO, SWCLK, GND and other pins in the SWD 20pin pin 24 of the emulator to the 4pin pin 23 of the CDC module;

[0070] (3) Connecting the DAC interface 25 of the emulator 20 to the USB interface of the host computer 18;

[0071] (4) Connect the sensor unit 16 to the 8-pin pin 21 on the CDC module 20 to achieve current supply and capacitance signal extraction;

[0072] (5) Connect both ends of the sensor to the oil pipeline. When wear particles exist in the oil, the signal data processing program of the host computer will show an upward data peak.

[0073] In the embodiment of the present invention, wear particle detection is performed by an oil detection system based on a wear particle sensor device of a differential coaxial capacitor, as shown in FIG. Figure 8 , Fig. 9 As shown in the figure, the real-time detection data of wear particles is as follows: Figure 8 As shown in the figure, the horizontal axis represents the time change and the vertical axis represents the capacitance monitoring value; the wear particle detection range is as follows: Fig. 9 As shown, the horizontal axis represents the equivalent diameter of the abrasive particles, the vertical axis represents the capacitance change value, the blue dots in the figure represent the monitoring values ​​of the iron abrasive particles, and the red dots represent the monitoring values ​​of the copper abrasive particles; the oil detection system can detect iron particles larger than 100 microns and copper particles larger than 300 microns in the oil.

[0074] To sum up, in the embodiment of the present invention, the crosstalk between electrodes is reduced through the integrated differential monitoring structure, the sensitivity of the sensing device is improved, and thus the accuracy of metal abrasive particle detection is also improved; and compared with the existing sensor design, the processing difficulty is low, the structural reliability is high and the circuit design cost is low.

[0075] Furthermore, in the embodiment of the present invention, the noise of circuit interference is reduced through differential detection, thereby improving the signal-to-noise ratio.

[0076] In addition, in the embodiment of the present invention, the coaxial capacitor design effectively reduces the equivalent spacing between the plates, and further improves the sensitivity of the sensor device.

[0077] Embodiment 3

[0078] Corresponding to the above device embodiment, another aspect of the present invention provides a wear particle detection method, such as Fig.10 As shown, the steps include:

[0079] S11, preset the level of the annular electrode; ground the cylindrical electrode; and energize the abrasive particle sensing device according to the preset level to obtain two capacitance signal data;

[0080] In the embodiment of the present invention, the two capacitance signal data are specifically: capacitance change data containing the same wear particle information detected on two metal outer plates under similar time and the same detection method.

[0081] In a specific implementation, the preset level of the annular electrodes 1 and 2 may be a 3.3V direct current, the cylindrical electrode 3 is grounded, and then two capacitance signal data are obtained.

[0082] S12, calculating the mean and difference according to the capacitance signal data, and performing zero point shift according to the difference; the difference is the difference between the value of each capacitance signal and the mean;

[0083] In the embodiment of the present invention, the average value is calculated by using two capacitance signal data, and the difference between the capacitance signal value and the average value is calculated, and then the zero point is shifted.

[0084] S13, filtering the two capacitance signals after zero point shift;

[0085] In the embodiment of the present invention, the filtering process of the two capacitance signals after zero point shift includes: reducing noise signals by Kalman filtering.

[0086] Specifically, the initial state mean of the Kalman filter is set to the first value of the processed data sequence, the observation matrix and the transfer matrix are the unit matrix, and the state transition noise covariance is selected to be a smaller level;

[0087] S14, performing differential calculation and threshold extraction on the two capacitance signal data after filtering to obtain a capacitance pulse signal peak value;

[0088] In the embodiment of the present invention, performing differential calculation on the two capacitance signal data after filtering includes:

[0089] c i =αA i +βA′ i

[0090] In the formula, A i , A′ i They are two capacitance change arrays respectively, α and β are compensation coefficients used to correct the statistical deviation of the two signals. The noise change range is used as the judgment standard. After the abnormal noise points are removed by filtering, the conventional noise point range is statistically analyzed. Since it is a differential calculation, the value of β is a negative number. Since the result is affected by the array amplitude, and the detection method of the two signals is the same and the detection time is similar, the compensation coefficient in this formula is between 97% and 102%, and its size is positively correlated with the noise range.

[0091] In the embodiment of the present invention, the threshold value extraction is to extract the peak value of the sinusoidal pulse signal.

[0092] S15, obtaining abrasive particle detection results according to the peak value of the capacitance pulse signal and the abrasive particle size parameters.

[0093] In the embodiment of the present invention, the abrasive particle detection result is obtained by using the peak value of the capacitive pulse signal and the abrasive particle size parameter, and iron particles with a diameter of 100 microns and copper particles with a diameter of 300 microns can be detected.

[0094] It should be noted that since the wear particle detection method in the embodiment of the present invention is a specific usage of the first embodiment, the beneficial effects obtained are consistent with the beneficial effects of the wear particle sensing device based on differential coaxial capacitors in the first embodiment, and will not be repeated here.

[0095] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A wear particle sensing device based on differential coaxial capacitance, characterized in that: include: A circular metal electrode and a cylindrical metal electrode for generating an electrostatic field, and a flange structure for supporting fixation; wherein, The flange structure comprises a left flange, a right flange and a flange connector; The cylindrical metal electrode is arranged at the exact center of the lubricating oil flow channel of the sensor device and is fixed by the flange structure; the annular metal electrode is arranged on the inner boss of the left flange and the inner boss of the right flange, and the inner boss of the left flange and the inner boss of the right flange are embedded in the flange connector.

2. The wear particle sensing device based on differential coaxial capacitance according to claim 1 is characterized in that: There are two circular metal electrodes.

3. The wear particle sensing device based on differential coaxial capacitance according to claim 2 is characterized in that: The center of the left flange and the center of the right flange are both provided with grooves; and the support column of the right flange is provided with a wire hole.

4. The wear particle sensor device based on differential coaxial capacitance according to claim 1 is characterized in that: The flange connector is provided with grooves at the center and on both sides; the groove at the center of the flange connector is used to install a metal isolation plate; the grooves on both sides of the flange connector are respectively used to embed the inner boss of the left flange and the inner boss of the right flange.

5. The wear particle sensing device based on differential coaxial capacitance according to claim 4 is characterized in that: The metal isolation plates are semicircular and there are two of them.

6. The wear particle sensor device based on differential coaxial capacitance according to claim 5 is characterized in that: The metal isolation plate and the flange connection piece are provided with wire holes.

7. The wear particle sensor device based on differential coaxial capacitance according to claim 1, characterized in that: Also includes: A metal protective cover for electromagnetic shielding; the metal protective cover is a single-layer metal shielding layer, which is threadedly connected by a left shell and a right shell.

8. A wear particle detection method, used in the wear particle sensing device based on differential coaxial capacitance as claimed in any one of claims 1 to 7, characterized in that: Includes steps: S11, preset the level of the circular ring electrode; The cylindrical electrode is grounded; and the abrasive particle sensing device is powered according to a preset level to obtain two capacitance signal data; S12, calculating the mean and difference according to the capacitance signal data, and performing zero point shift according to the difference; the difference is the difference between the value of each capacitance signal and the mean; S13, filtering the two capacitance signals after zero point shift; S14, performing differential calculation and threshold extraction on the two capacitance signal data after filtering to obtain a capacitance pulse signal peak value; S15, obtaining abrasive particle detection results according to the peak value of the capacitance pulse signal and the abrasive particle size parameters.

9. The wear particle detection method according to claim 8, characterized in that: The filtering process of the two capacitance signals after zero point shifting includes: Kalman filtering is used to reduce the noise signal.

10. The wear particle detection method according to claim 8, characterized in that: The performing differential calculation on the two capacitance signal data after filtering includes: c i =αA i +βA′ i In the formula, A i , A′ i They are two capacitance change arrays respectively; α and β are compensation coefficients, and the value of β is a negative number.

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