Plug-in gearbox oil debris on-line monitoring sensor and monitoring method thereof

Abstract

The application provides an online monitoring sensor for gear box oil debris insertion and a monitoring method thereof, and relates to the field of sensors.The sensor comprises an excitation coil and an induction coil, the excitation coil and the induction coil are parallelly wound on a silicon steel sheet, the surface area of the excitation coil is larger than that of the induction coil, the inductance of the excitation coil and the induction coil is the same and the LC resonance frequency is the same after being connected in parallel with the same capacitor, a cylindrical magnetic field shielding cover is arranged outside the induction coil, a plurality of through holes for particles to pass through are arranged on the magnetic field shielding cover, the induction coil generates a modulated signal carrying particle information and outputs the modulated signal to a processing circuit, and the particle modulated signal in the oil is extracted by the processing circuit.The excitation coil and the induction coil are mounted on the silicon steel sheet, the silicon steel sheet soft magnetic material is adopted to replace the permanent magnet, the magnetic field is weak, particles are not adsorbed, the sensor can work for a long time, cleaning is not needed, and the service life of the whole sensor can be prolonged.

Description

Technical Field

[0001] This invention belongs to the field of sensors, and specifically relates to an insertable online monitoring sensor for lubricating oil debris in gearboxes and its monitoring method. Background Technology

[0002] Many current online lubricating oil debris sensors employ a three-coil modulation principle, exhibiting high sensitivity and the ability to detect ferromagnetic particles larger than 125µm. However, they have limitations, requiring installation within oil flow pipelines. Given the current need for gearbox monitoring in airborne or ground-based applications, where oil flow is often unavailable, this sensor was invented to address this requirement.

[0003] Based on on-site feedback and technical data, current magnetic plug-type debris monitoring sensors utilize a permanent magnet structure, relying on the permanent magnet to attract and detect particles. During on-site operation, the following issues arise: 1) Personnel need to clean the attracted debris regularly, sometimes multiple times a day; 2) The magnetic field of the permanent magnet is easily interfered with by rotating gear sets or metal components. To reduce interference, the detection threshold needs to be increased, leading to frequent missed detections; 3) Generally, permanent magnet magnetic plug sensors can only detect ferromagnetic metal debris and cannot detect non-ferromagnetic metal debris, such as copper, aluminum, and silver.

[0004] Patent 202211706969.1 - A high-precision magnetic plug abrasive sensor, essentially based on a permanent magnet structure, utilizes the symmetry of a bridge for amplification. Patent 202410549337.1 - A high-precision magnetic plug sensor, providing a sensor constructed with a permanent magnet, consisting of a large excitation coil with several induction coils nested within it, and then using a diode half-wave rectifier circuit for envelope detection. Patent 201910183082.0 - An inductive magnetic plug-type online oil monitoring device, using a solenoid coil wound around a permanent magnet, then AC excitation, with an excitation-detection unit detection method. Patent 202111233711.X - A magnetic plug-type ferrous metal particle detection sensor and a magnetic plug-type balanced bridge measurement circuit. Provides a measurement circuit based on a bridge structure.

[0005] In summary, current technology can only detect metal debris and cannot detect non-ferromagnetic metal debris such as copper, aluminum, and silver. It is also inconvenient to clean and causes many inconveniences during use. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides an insertion-type online monitoring sensor for lubricating oil debris in gearboxes and its monitoring method. This invention can be used in oil-free pipeline flow equipment such as gearboxes for online insertion-type monitoring of lubricating oil debris. The excitation coil and induction coil of this invention are mounted on silicon steel sheets, using soft magnetic materials on the silicon steel sheets instead of permanent magnets. This results in a weaker magnetic field that does not attract particles, allowing for long-term operation without cleaning and extending the overall sensor lifespan. Furthermore, since ferromagnetic and non-ferromagnetic metal debris affect the magnetic field differently—ferromagnetic debris enhances the magnetic field strength while non-ferromagnetic debris weakens it—this invention can also detect non-ferromagnetic metal debris, expanding its application scenarios and enabling long-term continuous online monitoring of lubricating oil debris in oil-free pipeline environments such as gearboxes.

[0007] To achieve the above objectives, the present invention discloses the following technical solution:

[0008] Specifically, on the one hand, the present invention provides an insertable gearbox lubricating oil debris online monitoring sensor that can be inserted into a pipeline or oil tank. It includes an excitation coil and an induction coil, which are wound in parallel on a silicon steel sheet. The surface area of ​​the excitation coil is larger than that of the induction coil. The excitation coil and the induction coil have the same LC resonant frequency after being connected in parallel with the same capacitance. A cylindrical magnetic field shield is provided outside the induction coil. The magnetic field shield has multiple through holes for particles to pass through. The excitation current flows in from the first end of the excitation coil. The second end of the excitation coil is connected to the first end of the induction coil. When particles pass through the magnetic field shield, they enter the inside of the magnetic field shield through the through holes. The induction coil generates a modulation signal carrying particle information and outputs it to the processing circuit. The processing circuit extracts the particle modulation signal in the oil. The particle modulation signal is related to the particle size in the oil.

[0009] The processing circuit includes a primary amplifier circuit, a demodulation circuit, a high-gain amplifier, and a digital processing unit. The primary amplifier circuit is used to initially amplify the particle modulation signal. The demodulation circuit uses a multiplier or other phase-sensitive demodulation circuit to demodulate the amplified particle signal. The high-gain amplifier is used to amplify the demodulated particle signal a second time. The digital processing unit performs digital filtering on the particle signal, calculates the amplitude of the metal particle signal, and obtains the signal waveform generated when the particle passes through. Ferromagnetic and non-ferromagnetic signals are out of phase. The ferromagnetic signal waveform is mt1, and the non-ferromagnetic particle signal waveform is -mt1.

[0010] When the excitation coil is working, it begins to resonate with the resonant circuit through the excitation circuit, forming a carrier wave for the excitation circuit. The formula for the carrier wave H is as follows:

[0011] H = Asin(ωt + φ)

[0012] Where ωt is the frequency, A is the amplitude, and φ is the phase;

[0013] When particles pass through the induction coil, a particle modulation signal is generated. for:

[0014]

[0015] Where mt1 is the waveform generated when the particle passes through, and the demodulated signal is obtained through phase demodulation.

[0016]

[0017] Further calculations yielded the following:

[0018]

[0019] After low-pass filtering, the following is obtained:

[0020]

[0021] Finally, the waveforms generated when the particles pass through are obtained. Due to different magnetic effects, ferromagnetic particles and non-ferromagnetic particles have opposite phases. The signal of ferromagnetic particles is mt1, and the signal of non-ferromagnetic particles is -mt1.

[0022] Preferably, the inductance value of the induction coil, the LC resonant frequency, and the excitation current are adjusted according to specific requirements. The sensitivity of the sensor can be adjusted by adjusting the inductance value of the induction coil.

[0023] Preferably, the magnetic field shield has four through holes with a diameter of 6mm-12mm.

[0024] Preferably, the silicon steel sheet has a cylindrical structure.

[0025] Preferably, the diameter of the silicon steel sheet is 5mm-20mm, and the length of the silicon steel sheet is 30mm-100mm.

[0026] Preferably, the digital processing unit is a DSP processor or an FPGA processor.

[0027] Preferably, the LC resonant frequency is 100kHz and the excitation current is 35mA.

[0028] Preferably, the induction coil and the excitation coil are respectively connected in parallel with a capacitor to form an LC resonant circuit.

[0029] On the other hand, the present invention provides a monitoring method based on the above-mentioned insertion-type gearbox lubricating oil debris online monitoring sensor, which includes the following steps:

[0030] S1. Apply excitation current. The excitation current flows into the first end of the excitation coil and further into the induction coil.

[0031] S2. When the particles pass through the magnetic field shield, they enter the inside of the magnetic field shield through the through hole. The induction coil will generate a modulation signal carrying the particle information and output it to the processing circuit.

[0032] S3. The processing circuit extracts the particle modulation signal from the oil.

[0033] S4. The primary amplifier circuit is used to initially amplify the particle modulation signal. The demodulation circuit uses a multiplier or other phase-sensitive demodulation circuit to demodulate the amplified particle signal. The high-gain amplifier is used to amplify the demodulated particle signal a second time. The digital processing unit performs digital filtering on the particle signal and calculates the amplitude of the metal particle signal to obtain the signal waveform generated when the particle passes through. Ferromagnetic and non-ferromagnetic signals are out of phase. The ferromagnetic signal waveform is mt1, and the non-ferromagnetic particle signal waveform is -mt1.

[0034] Preferably, the calculation of the amplitude of the metal particle signal and the obtaining of the signal waveform generated when the particle passes through in step S4 are as follows:

[0035] When the excitation coil is working, it begins to resonate with the resonant circuit through the excitation circuit, forming a carrier wave for the excitation circuit. The formula for the carrier wave H is as follows:

[0036] H = Asin(ωt + φ)

[0037] Where ωt is the frequency, A is the amplitude, and φ is the phase;

[0038] When particles pass through the induction coil, a particle modulation signal is generated. for:

[0039]

[0040] Where mt1 is the waveform generated when the particle passes through, and the demodulated signal is obtained through phase demodulation.

[0041]

[0042] Further calculations yielded the following:

[0043]

[0044] After low-pass filtering, the following is obtained:

[0045]

[0046] Finally, the waveforms generated when the particles pass through are obtained. Due to different magnetic effects, ferromagnetic particles and non-ferromagnetic particles have opposite phases. The signal of ferromagnetic particles is mt1, and the signal of non-ferromagnetic particles is -mt1.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] (1) This invention provides a high-sensitivity insertion-type online monitoring sensor for lubricating oil debris based on the signal modulation principle. It consists of an LC resonant excitation coil that provides a carrier wave and an induction coil for modulating signal output. The excitation coil and the induction coil are mounted on silicon steel sheets. The silicon steel sheets are made of soft magnetic material, replacing permanent magnets. The magnetic field is weak, does not attract particles, can work for a long time, does not require cleaning, is more convenient to use, and can extend the service life of the overall sensor.

[0049] (2) The insertion-type online monitoring sensor for lubricating oil debris of the present invention adopts a silicon steel sheet structure, eliminating the need for permanent magnet adsorption. When particles enter the magnetic field, the magnetic field of the excitation coil and the magnetic field generated by the particles interact and are modulated into the output of the induction coil, assisting the high-sensitivity processing circuit at the back end for more accurate detection of metal debris particles. Furthermore, because ferromagnetic and non-ferromagnetic metal debris affect the magnetic field differently—ferromagnetic particles can enhance the magnetic field strength, while non-ferromagnetic particles can reduce it—the present invention can also detect non-ferromagnetic metal debris, thus expanding its application scenarios.

[0050] (3) In order to reduce the influence of moving metal components such as rotating gears on the magnetic field of the sensor, the online monitoring sensor of the present invention adds a magnetic field shield at the top of the induction coil, which can reduce some external magnetic field interference, thereby ensuring more accurate monitoring results. Attached Figure Description

[0051] Figure 1 This is a schematic diagram of the sensor structure of the present invention;

[0052] Figure 2 This is a schematic diagram of the signal processing circuit structure of the present invention;

[0053] Figure 3 This is a schematic diagram of the LC parallel resonance of the present invention;

[0054] Figure 4 This is a schematic diagram of the method flow of the present invention. Detailed Implementation

[0055] Exemplary embodiments, features, and aspects of the present invention will now be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings denote elements that have the same or similar functions. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0056] This invention provides an insertable online monitoring sensor for gearbox lubricating oil debris, which can be inserted into a pipeline or oil tank, such as... Figure 1 As shown, it includes an excitation coil 2 and an induction coil 3, which are wound in parallel on a silicon steel sheet 1. The surface area of ​​the excitation coil 2 is larger than that of the induction coil 3. The excitation coil 2 and the induction coil 3 are connected in parallel with the same capacitance and have the same LC resonant frequency. A cylindrical magnetic field shield 5 is provided outside the induction coil 3. The magnetic field shield 5 is provided with multiple through holes 4 for particles to pass through. The excitation current flows in from the first end of the excitation coil, and the second end of the excitation coil is connected to the first end of the induction coil. When particles pass through the magnetic field shield 5, they enter the interior of the magnetic field shield 5 through the through holes. The induction coil 3 generates a modulation signal carrying particle information and outputs it to the processing circuit. The processing circuit extracts the particle modulation signal in the oil. The particle modulation signal is related to the particle size in the oil.

[0057] The processing circuit includes a primary amplifier circuit, a demodulation circuit, a high-gain amplifier, and a digital processing unit. The primary amplifier circuit is used to initially amplify the particle modulation signal. The demodulation circuit uses a multiplier or other phase-sensitive demodulation circuit to demodulate the amplified particle signal. The high-gain amplifier is used to amplify the demodulated particle signal a second time. The digital processing unit performs digital filtering on the particle signal, calculates the amplitude of the metal particle signal, and obtains the signal waveform generated when the particle passes through. When the signal waveform is mt1, the particle is a ferromagnetic particle. When the signal waveform is -mt1, the particle is a non-ferromagnetic particle.

[0058] When the excitation coil is working, it begins to resonate with the resonant circuit through the excitation circuit, forming a carrier wave for the excitation circuit. The formula for the carrier wave H is as follows:

[0059] H = Asin(ωt + φ)

[0060] Where ωt is the frequency, A is the amplitude, and φ is the phase.

[0061] When particles pass through the induction coil, a particle modulation signal is generated. for:

[0062]

[0063] Where mt1 is the waveform generated when the particle passes through, which can be obtained through phase demodulation:

[0064]

[0065] Further calculations:

[0066]

[0067] Since cos 2ωt has a high frequency, after low-pass filtering, we get:

[0068]

[0069] Finally, the mt1 waveform generated when the particles pass through is obtained. Due to different magnetic effects, ferromagnetic particles and non-ferromagnetic particles have opposite phases. The signal of ferromagnetic particles is mt1, and the signal of non-ferromagnetic particles is -mt1.

[0070] On the other hand, the present invention provides a monitoring method based on the above-mentioned insertion-type gearbox lubricating oil debris online monitoring sensor, such as... Figure 4 As shown, it includes the following steps:

[0071] S1. Apply excitation current. The excitation current flows into the first end of the excitation coil and then into the induction coil.

[0072] S2. When the particles pass through the magnetic field shield, they enter the inside of the magnetic field shield through the through hole. The induction coil generates a modulation signal carrying the particle information and outputs it to the processing circuit.

[0073] S3, the processing circuit extracts the particle modulation signal from the oil.

[0074] S4. The primary amplifier circuit is used to initially amplify the particle modulation signal. The demodulation circuit uses a multiplier or other phase-sensitive demodulation circuit to demodulate the amplified particle signal. The high-gain amplifier is used to amplify the demodulated particle signal a second time. The digital processing unit performs digital filtering on the particle signal and calculates the amplitude of the metal particle signal to obtain the signal waveform generated when the particle passes through. Ferromagnetic and non-ferromagnetic signals are out of phase. The ferromagnetic signal waveform is mt1, and the non-ferromagnetic particle signal waveform is -mt1.

[0075] Preferably, the calculation of the amplitude of the metal particle signal and the obtaining of the signal waveform generated when the particle passes through in step S4 are as follows:

[0076] When the excitation coil is working, it begins to resonate with the resonant circuit through the excitation circuit, forming a carrier wave for the excitation circuit. The formula for the carrier wave H is as follows:

[0077] H = Asin(ωt + φ)

[0078] Where ωt is the frequency, A is the amplitude, and φ is the phase.

[0079] When particles pass through the induction coil, a particle modulation signal is generated. for:

[0080]

[0081] Where mt1 is the waveform generated when the particle passes through, and the demodulated signal is obtained through phase demodulation.

[0082] Further calculations yielded the following:

[0083]

[0084] After low-pass filtering, the following is obtained:

[0085]

[0086] Finally, the waveforms generated when the particles pass through are obtained. Due to different magnetic effects, ferromagnetic particles and non-ferromagnetic particles have opposite phases. The signal of ferromagnetic particles is mt1, and the signal of non-ferromagnetic particles is -mt1. Specific Implementation

[0088] Specifically, the present invention provides an insertable gearbox lubricating oil debris online monitoring sensor, which can be inserted into a pipeline or oil tank, such as... Figure 1 As shown, it includes an excitation coil 2 and an induction coil 3, which are wound side-by-side on a silicon steel sheet 1, which has a cylindrical structure. The diameter of the silicon steel sheet 1 is 5mm-20mm, and the length of the silicon steel sheet 1 is 30mm-100mm.

[0089] The surface area of ​​the excitation coil 2 is larger than that of the induction coil 3. The excitation coil 2 and the induction coil 3 have the same inductance and, after being connected in parallel with the same capacitor, have the same LC resonant frequency. The excitation coil and the induction coil are connected in parallel with the capacitor to form an LC resonant circuit, and their resonant frequencies must be the same. Adjusting the inductance of the induction coil can improve the sensor's sensitivity in detecting debris. Increasing the inductance of the induction coil requires a proportional decrease in the value of the capacitor connected in parallel to ensure that the excitation coil and the induction coil have the same resonant frequency. In a more specific embodiment, the LC resonator can be a commonly used LC parallel resonant circuit such as an AC bridge, a transistor circuit, or a transformer. A cylindrical magnetic field shield is provided outside the induction coil 3. The magnetic field shield has multiple through holes for particles to pass through. In one embodiment, the magnetic field shield has four through holes with a diameter of 6mm-12mm. Excitation current flows in from the first end of excitation coil 2. The second end of excitation coil 2 is connected to the first end of induction coil 3. When particles pass through the magnetic field shield, they enter the inside of the magnetic field shield through the through hole. Induction coil 3 generates a modulation signal carrying particle information and outputs it to the processing circuit. The processing circuit extracts the particle modulation signal in the oil. The particle modulation signal is related to the particle size in the oil.

[0090] The processing circuit includes a primary amplifier circuit, a demodulation circuit, a high-gain amplifier, and a digital processing unit. The primary amplifier circuit is used to initially amplify the particle modulation signal. The demodulation circuit uses a multiplier or other phase-sensitive demodulation circuit to demodulate the amplified particle signal. The high-gain amplifier is used to amplify the demodulated particle signal a second time. The digital processing unit performs digital filtering on the particle signal and calculates the amplitude of the metal particle signal; the digital processing unit is a DSP processor or an FPGA processor. In specific applications, the inductance value, LC resonant frequency, and excitation current of the induction coil 3 are adjusted according to specific requirements. In one specific embodiment, the LC resonant frequency is 100kHz, and the excitation current is 35mA. The LC resonant parameters are consistently selected to achieve a better resonant frequency. The magnetic field shield, made of a conductive material with good conductivity, is used to reduce the disturbance of the magnetic field by the movement of metal particles other than metal shavings. The shield has four through holes with a diameter of 6mm-12mm.

[0091] When excitation coil 2 is working, it begins to resonate with the resonant circuit through the excitation circuit, forming the excitation circuit carrier wave. The formula for the carrier wave H is as follows:

[0092] H = Asin(ωt + φ)

[0093] Where ωt is the frequency.

[0094] ωt represents the frequency. The carrier frequency should be much higher than the frequency at which the particles appear, typically around 100kHz. When a particle passes through, an amplitude-modulated signal is generated. When a particle passes through the induction coil, a particle modulation signal is generated. for:

[0095]

[0096] Where mt1 is the waveform generated when the particle passes through:

[0097]

[0098] Where mt1 represents the effect of the particle passing through on the signal amplitude, and its frequency is relatively low. Due to the low energy utilization rate of the particle in the magnetic field, mt1 is much smaller than A, resulting in a relatively low modulation index. When processing with the processing circuit, a phase-sensitive demodulation method is used, employing the multiplication of functions with the same frequency and phase.

[0099] Calculations show that:

[0100]

[0101] Since cos 2ωt has a high frequency, after low-pass filtering, we get:

[0102]

[0103] Finally, the mt1 waveform generated when the particles pass through is obtained. Due to different magnetic effects, ferromagnetic particles and non-ferromagnetic particles have opposite phases. The signal of ferromagnetic particles is mt1, and the signal of non-ferromagnetic particles is -mt1.

[0104] This embodiment provides a high-sensitivity insertion-type online monitoring sensor for lubricating oil debris based on the signal modulation principle, such as... Figure 1 As shown, the excitation coil 2 and the induction coil 3 are mounted on the silicon steel sheet 1 using the same parameters and processes. According to Lenz's theorem, the direction of the induced current is opposite to the direction of the excitation current. A magnetic field shield 5 is installed outside the induction coil 3. The magnetic field shield 5 has multiple large through holes 6 that allow particles to flow freely. When a metal particle 4 enters the magnetic field shield 5 through the large through holes 6, it will interact with the magnetic field of the excitation coil 2, generating a modulation signal, which is output through the induction coil 3 and then processed by a dedicated processing circuit.

[0105] like Figure 3 As shown, excitation coil 2 and capacitor 9 form an LC parallel resonance, and induction coil 3 and capacitor 10 form an LC parallel resonance. The resonant frequencies of excitation coil 2 and induction coil 3 must be the same, but their inductance values ​​can be different. In practical applications, increasing the inductance value of induction coil 3 can appropriately increase the sensitivity. Therefore, the inductance value of induction coil 3 can be adjusted as needed.

[0106] like Figure 2 As shown, the processing circuit includes a primary amplifier circuit, a demodulation circuit, a high-gain amplifier, and a data processing unit. The primary amplifier circuit includes amplifier A, amplifier B, and a DC blocking capacitor 7. The demodulation circuit includes a demodulator 8 and a low-pass filter. The high-gain amplifier includes high-gain amplifier A and high-gain amplifier B. The data processing unit includes an ADC acquisition unit and a DSP data processor. Due to the divergence of the magnetic field, the modulation index of the modulation signal in the induction coil 3 is relatively low. Amplifier A, DC blocking capacitor 7, and amplifier B perform primary amplification and shaping of the modulation signal. After passing through demodulator 8 and low-pass filtering, high-gain amplifiers A and B are used for high-gain amplification to improve sensitivity. Demodulator 8 can be composed of a multiplier or a phase-sensitive demodulator. The amplification factor of high-gain amplifiers A and B can be set between 1000x and 10000x as needed.

[0107] The diameter and length of the silicon steel sheet 1 can be configured according to actual conditions. Generally, the diameter can be set to around 10mm and the length to around 50mm. The excitation coil 2 and the induction coil 3 use copper enameled wire, with a copper diameter of around 0.22mm. Under normal circumstances, the number of turns in the excitation coil 2 and the induction coil 3 can be equal. In this embodiment, the number of turns in both the excitation coil 2 and the induction coil 3 is set to around 100 turns.

[0108] This invention mounts the excitation coil 2 and induction coil 3 on a silicon steel sheet 1, using the soft magnetic material of silicon steel to replace permanent magnets. This results in a weaker magnetic field, which does not attract particles, allowing for long-term operation without cleaning, making it more convenient to use and extending the overall sensor's lifespan. When a particle enters the magnetic field, the magnetic field of the excitation coil and the magnetic field generated by the particle interact, modulating the output signal in the induction coil. The processing circuit then detects metal debris particles with higher precision. Furthermore, because ferromagnetic and non-ferromagnetic metal debris affect the magnetic field differently—ferromagnetic particles can enhance the magnetic field strength, while non-ferromagnetic particles can reduce it—this invention can also detect non-ferromagnetic metal debris, expanding its application scenarios.

[0109] The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. An insertable online monitoring sensor for lubricating oil debris in gearboxes, capable of being inserted into a pipeline or oil tank, characterized in that: It includes an excitation coil and an induction coil, which are wound in parallel on a silicon steel sheet. The surface area of ​​the excitation coil is larger than that of the induction coil. The excitation coil and the induction coil have the same LC resonant frequency after being connected in parallel with a capacitor. A cylindrical magnetic field shield is provided outside the induction coil. The magnetic field shield has multiple through holes for particles to pass through. The excitation current flows in from the first end of the excitation coil. The second end of the excitation coil is connected to the first end of the induction coil. When the particles pass through the magnetic field shield, they enter the inside of the magnetic field shield through the through holes. The induction coil generates a modulation signal carrying particle information and outputs it to the processing circuit. The processing circuit extracts the particle modulation signal in the oil. The particle modulation signal is related to the particle size in the oil. The processing circuit includes a primary amplifier circuit, a demodulation circuit, a high-gain amplifier, and a digital processing unit. The primary amplifier circuit is used to initially amplify the particle modulation signal. The demodulation circuit uses a multiplier or other phase-sensitive demodulation circuit to demodulate the amplified particle signal. The high-gain amplifier is used to amplify the demodulated particle signal a second time. The digital processing unit performs digital filtering on the particle signal and calculates the amplitude of the metal particle signal, and obtains the signal waveform generated when the particle passes through. Ferromagnetic and non-ferromagnetic signals are out of phase. The waveform of the ferromagnetic particle signal is mt1, and the waveform of the non-ferromagnetic particle signal is -mt1. The particle can be determined as a ferromagnetic particle or a non-ferromagnetic particle by the waveform. When the excitation coil is working, it begins to resonate with the resonant circuit through the excitation circuit, forming the excitation circuit carrier wave. The carrier wave H is formulated as follows: H = Asin(ωt + φ) Where ωt is the frequency, A is the amplitude, and φ is the phase; When particles pass through the induction coil, a particle modulation signal is generated. for; Where mt1 is the waveform generated when the particle passes through, and the demodulated signal is obtained through phase demodulation. Further calculations yielded the following: After low-pass filtering, the following is obtained: Finally, the waveforms generated when the particles pass through are obtained. Due to different magnetic effects, ferromagnetic particles and non-ferromagnetic particles have opposite phases. The signal of ferromagnetic particles is mt1, and the signal of non-ferromagnetic particles is -mt1.

2. The insertion-type gearbox lubricating oil debris online monitoring sensor according to claim 1, characterized in that: The inductance of the induction coil, the LC resonant frequency, and the excitation current can be adjusted according to specific requirements. The sensitivity of the sensor can be adjusted by adjusting the inductance of the induction coil.

3. The insertion-type gearbox lubricating oil debris online monitoring sensor according to claim 1, characterized in that: The magnetic field shield has four through holes, the diameter of which is 6mm-12mm.

4. The insertion-type gearbox lubricating oil debris online monitoring sensor according to claim 1, characterized in that: The silicon steel sheet has a cylindrical structure.

5. The insertion-type gearbox lubricating oil debris online monitoring sensor according to claim 4, characterized in that: The diameter of the silicon steel sheet is 5mm-20mm, and the length of the silicon steel sheet is 30mm-100mm.

6. The insertion-type gearbox lubricating oil debris online monitoring sensor according to claim 1, characterized in that: The digital processing unit is a DSP processor or an FPGA processor.

7. The insertion-type gearbox lubricating oil debris online monitoring sensor according to claim 2, characterized in that: The LC resonant frequency is 100kHz and the excitation current is 35mA.

8. The insertion-type gearbox lubricating oil debris online monitoring sensor according to claim 1, characterized in that: The induction coil and the excitation coil are each connected in parallel with a capacitor to form an LC resonant circuit.

9. A monitoring method based on the insert-type gearbox lubricating oil debris online monitoring sensor according to claim 1, characterized in that: It includes the following steps: S1. Apply excitation current. The excitation current flows into the first end of the excitation coil and further into the induction coil. S2. When the particles pass through the magnetic field shield, they enter the inside of the magnetic field shield through the through hole. The induction coil will generate a modulation signal carrying the particle information and output it to the processing circuit. S3. The processing circuit extracts the particle modulation signal from the oil. S4. The primary amplifier circuit is used to initially amplify the particle modulation signal. The demodulation circuit uses a multiplier or other phase-sensitive demodulation circuit to demodulate the amplified particle signal. The high-gain amplifier is used to amplify the demodulated particle signal a second time. The digital processing unit performs digital filtering on the particle signal and calculates the amplitude of the metal particle signal to obtain the signal waveform generated when the particle passes through. Ferromagnetic and non-ferromagnetic signals are out of phase. The ferromagnetic signal waveform is mt1, and the non-ferromagnetic particle signal waveform is -mt1.

10. The monitoring method according to claim 9, characterized in that: In step S4, the amplitude of the metal particle signal is calculated, and the signal waveform generated when the particle passes through is obtained as follows: When the excitation coil is working, it begins to resonate with the resonant circuit through the excitation circuit, forming the excitation circuit carrier wave. The carrier wave H is formulated as follows: H = Asin(ωt + φ) Where ωt is the frequency, A is the amplitude, and φ is the phase; When particles pass through the induction coil, a particle modulation signal is generated. for: Where mt1 is the waveform generated when the particle passes through, and the demodulated signal is obtained through phase demodulation. Further calculations yielded the following: After low-pass filtering, the following is obtained: Finally, the waveforms generated when the particles pass through are obtained. Due to different magnetic effects, ferromagnetic particles and non-ferromagnetic particles have opposite phases. The signal of ferromagnetic particles is mt1, and the signal of non-ferromagnetic particles is -mt1.

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