Five-coil differential electromagnetic induction on-line monitoring system for oil abrasive particles

Abstract

This invention relates to the field of mechanical equipment fault detection technology, and more particularly to a five-coil differential electromagnetic induction online monitoring system for oil abrasive particles. The system includes a five-coil oil abrasive particle detection sensor, a signal acquisition module, a signal processing module, a power supply module, and a high-frequency excitation module. The five-coil oil abrasive particle detection sensor comprises a first excitation coil, a second excitation coil, a third excitation coil, a first induction coil, and a second induction coil, all connected in series. This invention is less susceptible to interference from external environmental magnetic fields such as geomagnetism and mechanical vibrations, meeting industrial requirements. The sensor structure can be designed for different pipe diameters according to the oil circuit of the mechanical equipment, making it suitable for monitoring oil circuits with different throughputs, thus solving the problem of insufficient sensitivity in existing inductive monitoring technology for large-diameter pipelines.

Description

Technical Field

[0001] This invention relates to the field of mechanical equipment fault detection technology, and in particular to a five-coil differential electromagnetic induction online monitoring system for oil abrasive particles. Background Technology

[0002] Abrasive particles in hydraulic fluid can directly reflect the wear and fatigue state of mechanical parts. Detecting the size and concentration of abrasive particles can effectively predict the service life of parts and reduce economic losses caused by failures. Existing inductive online detection technology is susceptible to interference from external environmental magnetic fields such as geomagnetic environments, as well as mechanical vibrations, which affect the detection sensitivity. The radial position of abrasive particles in the pipeline also affects the detection sensitivity. Furthermore, it has certain requirements on the diameter of the hydraulic fluid pipes in mechanical equipment, and the detection accuracy of abrasive particles is relatively low in large-diameter pipes. Summary of the Invention

[0003] This invention aims to provide a five-coil differential electromagnetic induction online monitoring system for oil abrasive particles. It is not easily affected by external environmental magnetic fields such as geomagnetism and mechanical vibration, thus meeting industrial needs. The sensor structure can be designed with different pipe diameters according to the oil circuit of mechanical equipment, making it suitable for monitoring oil circuits with different throughputs. This solves the problem of insufficient sensitivity of existing inductive monitoring technology in large-diameter pipelines.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A five-coil differential electromagnetic induction online monitoring system for oil abrasive particles includes: a five-coil oil abrasive particle detection sensor, a signal acquisition module, a signal processing module, a power supply module, and a high-frequency excitation module, wherein:

[0006] The five-coil oil abrasive detection sensor includes a first excitation coil, a second excitation coil, a third excitation coil, a first induction coil, and a second induction coil. The first excitation coil, the second excitation coil, and the third excitation coil are connected in series. The first excitation coil and the third excitation coil are wound counterclockwise, and the second excitation coil is wound clockwise. The first induction coil is located between the first excitation coil and the second excitation coil, and the second induction coil is located between the second excitation coil and the third excitation coil.

[0007] The high-frequency excitation module is connected to the first excitation coil and the third excitation coil and is used to output a sinusoidal current;

[0008] The signal acquisition module includes a first signal acquisition module and a second signal acquisition module. The first signal acquisition module is connected to the first induction coil, and the second signal acquisition module is connected to the second induction coil. The first signal acquisition module acquires the abrasive amplitude modulation signal output by the first induction coil, and the second signal acquisition module acquires the induction signal output by the second induction coil.

[0009] The signal processing module is connected to the first signal acquisition module and the second signal acquisition module respectively. It is used to perform differential processing on the abrasive amplitude modulation signal output by the first signal acquisition module and the induction signal output by the second acquisition signal module, and then pass them through a bandpass filter to obtain the abrasive signal.

[0010] The power supply module provides power to the high-frequency excitation module, the signal acquisition module, and the signal processing module.

[0011] Preferably, the signal acquisition module further includes a first sensing capacitor and a second sensing capacitor, wherein the first sensing capacitor is connected in parallel with the first sensing capacitor, and the second sensing capacitor is connected in parallel with the second sensing capacitor.

[0012] Preferably, the number of turns, length, and radius of the first excitation coil, the second excitation coil, and the third excitation coil are all equal.

[0013] Compared with the prior art, the beneficial effects of this application are as follows:

[0014] This invention employs a five-coil oil abrasive particle detection sensor. Three of the excitation coils, when energized with an excitation signal, generate an alternating magnetic field. Compared to existing technologies, this enhances the internal magnetic field, expands its coverage, and strengthens the magnetization and eddy current effects of metal particles, thus facilitating the extraction of abrasive particle characteristic signals. Two induction coils simultaneously output induction signals, providing differential signals for subsequent abrasive particle signal processing, effectively improving the signal-to-noise ratio (SNR) of abrasive particle signal detection. This invention uses differential processing for abrasive particle signal extraction. The abrasive particle amplitude modulation signal and the induction signal are equivalent to two differential traces. External noise interference is coupled to both traces almost simultaneously, and the signal processing module only takes the difference between the two signals. Therefore, external common-mode noise can be completely canceled out, resulting in stronger anti-interference capabilities compared to existing technologies. This optimized and improved SNR of abrasive particle signals is more conducive to abrasive particle signal identification and detection. This invention solves the problem of insufficient sensitivity in the detection of abrasive particles in large-diameter oil passages using existing technologies. It employs a five-coil oil abrasive particle detection sensor, which utilizes the symmetrical characteristics of the excitation magnetic field to form two zero-magnetic-field interfaces inside the sensor. This allows the abrasive particle amplitude modulation signal generated when the abrasive particle passes through the first induction coil to form a differential signal with the induction signal output by the second induction coil. Combined with subsequent signal processing using differential processing, interference is reduced and the signal-to-noise ratio is improved, achieving high-sensitivity detection in large-diameter oil passage applications. Attached Figure Description

[0015] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0016] Figure 1 This is a schematic diagram of the structure of the present invention;

[0017] Figure 2 Graph showing the magnetic field analysis of the excitation coil of a five-coil oil abrasive particle detection sensor;

[0018] Figure 3 The diagram shows the magnetic field distribution of the three sets of excitation coils;

[0019] Figure 4 The diagram shows the axial magnetic field distribution of the three sets of excitation coils.

[0020] Figure 5 The induction signal output by the induction coil when no abrasive particles pass through it;

[0021] Figure 6 This is the amplitude modulation signal of the abrasive particles output by the induction coil when the abrasive particles pass through it;

[0022] Figure 7 The signal is the ferromagnetic abrasive grain signal after processing by the signal processing module;

[0023] Figure 8 This is the non-ferromagnetic abrasive grain signal after processing by the signal processing module. Detailed Implementation

[0024] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0025] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0026] like Figure 1-7 As shown, the five-coil differential electromagnetic induction online monitoring system for oil abrasive particles includes: a five-coil oil abrasive particle detection sensor, a signal acquisition module, a signal processing module, a power supply module, and a high-frequency excitation module, wherein:

[0027] The five-coil oil abrasive detection sensor includes a first excitation coil, a second excitation coil, a third excitation coil, a first induction coil, and a second induction coil. The first excitation coil, the second excitation coil, and the third excitation coil are connected in series. The first excitation coil and the third excitation coil are wound counterclockwise, and the second excitation coil is wound clockwise. The first induction coil is located between the first excitation coil and the second excitation coil, and the second induction coil is located between the second excitation coil and the third excitation coil.

[0028] Under the same AC excitation signal, three sets of alternating magnetic fields of equal magnitude and opposite direction are generated inside the sensor. These magnetic fields cancel each other out at the midpoint between the first and second induction coils, forming a zero magnetic field. The magnetic field of the excitation coil is:

[0029]

[0030] In the formula, B is the magnetic induction intensity, μ0 is the free permeability, N is the number of turns per unit length of the coil, I is the excitation current amplitude, L is the coil length, x is the axial coordinate of the abrasive grain in the sensor, R1 is the inner diameter of the excitation coil, and R2 is the outer diameter of the excitation coil. Figure 4 The excitation magnetic field shown is close to zero at the center of the first and second induction coils. According to the principle of electromagnetic induction, under the excitation of an AC signal, the induction coil is in the alternating magnetic field generated by the excitation coil and will output an induced signal of the same frequency.

[0031] The high-frequency excitation module is connected to the first excitation coil and the third excitation coil to output a sinusoidal current and generate three sets of dynamic alternating magnetic fields with opposite polarities.

[0032] The signal acquisition module includes a first signal acquisition module and a second signal acquisition module. The first signal acquisition module is connected to the first induction coil, and the second signal acquisition module is connected to the second induction coil. The first signal acquisition module acquires the abrasive amplitude modulation signal output by the first induction coil, and the second signal acquisition module acquires the induction signal output by the second induction coil.

[0033] Metal abrasive particles mixed in the oil can be classified into ferromagnetic and non-ferromagnetic metal abrasive particles according to their material. When ferromagnetic metal abrasive particles with relatively high magnetic permeability flow through the alternating magnetic field generated by the excitation coil, the abrasive particles experience a strong magnetization effect, increasing the magnetic flux of the coil. When non-ferromagnetic metal abrasive particles with a relative magnetic permeability close to 1 flow through the sensor, the magnetization effect is very weak. Eddy currents are generated internally due to the eddy current effect. According to Lenz's law, the magnetic field direction of the eddy current is opposite to the original magnetic field direction, weakening the original magnetic field and reducing the magnetic flux of the coil. The change in axial magnetic flux when the abrasive particles pass through the induction coil is...

[0034] ΔΦ=ΔB·S=(μ r -1)πR 2 BV

[0035] In the formula μ r Let V be the relative permeability of the abrasive grain, V be the volume of the abrasive grain, and R be the diameter of the sensor tube. Based on the principle of inductance, the electromotive force output by the induction coil when the abrasive grain passes through the sensor is obtained as follows:

[0036]

[0037] In the formula, E is the induced electromotive force output by the induction coil, the rate of change of magnetic flux is determined by the velocity of the abrasive particles entering the sensor, and the induced signal output by the induction coil is affected by the excitation signal, generating an induced signal of the same frequency in the induction coil. When the abrasive particles enter the sensor, the magnetic field in the sensor is disturbed, such as... Figure 6 As shown, when the signal passes through the first induction coil, it outputs a wear particle amplitude modulation signal mounted on the induction signal, such as... Figure 5 As shown, at this time, the second induction coil outputs an induced signal generated by the alternating magnetic field generated by the excitation coil. After passing through the second induction coil, the second induction coil outputs a wear particle amplitude modulation signal, while the first induction coil outputs an induced signal generated by the alternating magnetic field generated by the excitation coil.

[0038] The signal processing module is connected to both the first and second signal acquisition modules. It performs differential processing on the abrasive amplitude modulation signal output from the first signal acquisition module and the induced signal output from the second signal acquisition module, then passes the signal through a bandpass filter to obtain the abrasive signal. By extracting the sampling points corresponding to the peak-to-peak values ​​of the abrasive signal, and calculating the abrasive velocity based on the difference in the number of sampling points and the length of the sensor, the frequency of the abrasive amplitude modulation signal can be measured. The number of abrasive particles passing through the sensor is calculated by accumulating the number of abrasive signals. Since the magnetic flux increases when ferromagnetic particles pass through the sensor, and decreases when non-ferromagnetic particles pass through the sensor, the abrasive signals generated by ferromagnetic and non-ferromagnetic abrasive particles have opposite phases. By detecting the amplitude, number, and phase of the abrasive signal, the size, number, and ferromagnetic properties of the metal abrasive particles in the oil can be obtained.

[0039] The power supply module provides power to the high-frequency excitation module, the signal acquisition module, and the signal processing module.

[0040] The signal acquisition module further includes a first sensing capacitor and a second sensing capacitor, wherein the first sensing capacitor is connected in parallel with the first sensing capacitor, and the second sensing capacitor is connected in parallel with the second sensing capacitor.

[0041] The number of turns, length, and radius of the first excitation coil, the second excitation coil, and the third excitation coil are all equal.

[0042] like Figure 3-4 As shown, the principle of an inductive metal abrasive particle detection sensor based on electromagnetic induction will be further explained with examples:

[0043] According to Biot-Saffar's law, the magnetic field of a circular current-carrying conductor is:

[0044]

[0045] In the differential inductive online oil wear particle monitoring system of this invention, the excitation coil and induction coil of the inductive wear particle detection sensor are made of multi-layer, multi-turn enameled wire. Therefore, the magnetic field of the excitation coil can be obtained by integrating the magnetic field model of the ring current-carrying conductor along the axial direction and then integrating it radially.

[0046]

[0047]

[0048] As shown in the above equation, the second excitation coil is wound in the opposite direction to the first and third excitation coils. The coils generate magnetic fields of equal magnitude but opposite direction inside, causing the magnetic field around the excitation coil to also change according to the law of electromagnetic induction, forming a changing magnetic field, such as... Figure 4 As shown, the magnetic field is close to zero at the center of the first and second induction coils, which provides the conditions for the generation of subsequent induction coil signals.

[0049] In the formula:

[0050] L is the coil length;

[0051] x is the distance from the reference point to the origin;

[0052] R1 is the inner diameter of the excitation coil;

[0053] R2 is the outer diameter of the excitation coil;

[0054] μ0 is the vacuum permeability;

[0055] I represents the current value of the AC excitation signal;

[0056] Abrasive grains of different materials and sizes mixed in the oil are magnetized and subjected to eddy current effects. When ferromagnetic metal abrasive grains (with a relative permeability μ) are mixed in the oil, they will react with each other. r >>1) The alternating magnetic field generated by the excitation coil has a strong magnetization effect on the abrasive grains, increasing the magnetic flux of the coil; when non-ferromagnetic metal abrasive grains (relative permeability μ) pass through the excitation coil, the magnetization effect on the abrasive grains is strong. r Approaching 1), the magnetization effect is very weak as the magnetic flux flows through the sensor. Due to the eddy current effect, eddy currents are generated internally. According to Lenz's law, the magnetic field direction of the eddy currents is opposite to the original magnetic field direction, thus weakening the original magnetic field and reducing the magnetic flux through the coil. The change in magnetic flux passing through the induction coil is:

[0057] ΔΦ=ΔB·S=(μ r -1)πR 2 BV

[0058] In the formula μ r Let V be the relative permeability of the abrasive grain, V be the volume of the abrasive grain, and R be the diameter of the sensor tube. Based on the principle of electromagnetic induction, the electromotive force output by the first induction coil when the abrasive grain passes through the sensor is obtained as follows:

[0059]

[0060] The induced signal output by the induction coil is affected by the excitation signal, generating an induced signal of the same frequency in the induction coil. When abrasive particles enter the sensor, the magnetic field in the sensor is disturbed, such as... Figure 6 As shown, when the signal passes through the first induction coil, it outputs a wear particle amplitude modulation signal mounted on the induction signal, such as... Figure 5 As shown, at this time, the second induction coil outputs an induced signal generated by the alternating magnetic field generated by the excitation coil. After passing through the second induction coil, the second induction coil outputs a wear particle amplitude modulation signal, while the first induction coil outputs an induced signal generated by the alternating magnetic field generated by the excitation coil.

[0061] The workflow of this invention is described in detail below:

[0062] Under the same excitation signal, three sets of magnetic fields of equal magnitude and opposite direction are generated inside the coil. At the midpoint of the induction coil, these magnetic fields cancel each other out, approaching zero. When metal abrasive particles pass through the sensor, they disturb the magnetic field within the sensor, causing the induction coil to generate an abrasive particle amplitude modulation signal. A signal acquisition module, composed of a first signal acquisition module and a second signal acquisition module, acquires the abrasive particle amplitude modulation signal output from the first induction coil and the induced signal output from the second induction coil. A signal processing module, connected to the signal acquisition module, first performs differential processing on the abrasive particle amplitude modulation signal output from the first acquisition module and the induced signal output from the second acquisition module, and then passes them through a bandpass filter to obtain the signal... Figure 7 The frequency of the abrasive amplitude modulation signal can be measured by extracting the sampling points corresponding to the peak-to-peak values ​​of the abrasive signal, calculating the abrasive velocity based on the difference in the number of sampling points and the length of the sensor, and then summing up the number of abrasive signals to calculate the number of abrasives passing through the sensor. By detecting the amplitude, number, and phase of the abrasive signal, the size, number, and ferromagnetic properties of the metal abrasives in the oil can be obtained.

[0063] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, component splitting or combination, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A five-coil differential electromagnetic induction online monitoring system for oil abrasive particles, characterized in that, include: The system comprises a five-coil oil wear particle detection sensor, a signal acquisition module, a signal processing module, a power supply module, and a high-frequency excitation module, wherein: The five-coil oil abrasive detection sensor includes a first excitation coil, a second excitation coil, a third excitation coil, a first induction coil, and a second induction coil. The first excitation coil, the second excitation coil, and the third excitation coil are connected in series. The first excitation coil and the third excitation coil are wound counterclockwise, and the second excitation coil is wound clockwise. The first induction coil is located between the first excitation coil and the second excitation coil, and the second induction coil is located between the second excitation coil and the third excitation coil. The high-frequency excitation module is connected to the first excitation coil and the third excitation coil and is used to output a sinusoidal current; The signal acquisition module includes a first signal acquisition module and a second signal acquisition module. The first signal acquisition module is connected to the first induction coil, and the second signal acquisition module is connected to the second induction coil. The first signal acquisition module acquires the abrasive amplitude modulation signal output by the first induction coil, and the second signal acquisition module acquires the induction signal output by the second induction coil. The signal processing module is connected to the first signal acquisition module and the second signal acquisition module respectively, and is used to perform differential processing on the abrasive amplitude modulation signal output by the first signal acquisition module and the induction signal output by the second signal acquisition module, and then pass them through a bandpass filter to obtain the abrasive signal. The power supply module provides power to the high-frequency excitation module, the signal acquisition module, and the signal processing module.

2. The five-coil differential electromagnetic induction online monitoring system for oil abrasive particles according to claim 1, characterized in that, The signal acquisition module further includes a first sensing capacitor and a second sensing capacitor, wherein the first sensing capacitor is connected in parallel with the first sensing capacitor and the second sensing capacitor is connected in parallel with the second sensing capacitor.

3. The five-coil differential electromagnetic induction online monitoring system for oil abrasive particles according to claim 1, characterized in that, The number of turns, length, and radius of the first excitation coil, the second excitation coil, and the third excitation coil are all equal.

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