A differential double-coil oil wear particle detection device based on excitation current signal

Abstract

The present invention belongs to the technical field of oil detection of wind turbine gearboxes, and specifically relates to a differential double-coil oil wear particle detection device based on an excitation current signal, which includes: a series resonant excitation circuit and a parallel resonant excitation circuit, an excitation signal generating module, an excitation current sampling module, a differential amplifier, and a micro industrial computer. During use, when ferromagnetic abrasive particles pass through the excitation coil, the excitation current of the series resonant excitation circuit is significantly reduced, and the excitation current of the parallel resonant excitation circuit is significantly increased. The current change directions of the two resonant excitation circuits are opposite, and the two can form a differential structure. The differential amplifier is used to make a difference in the effective values ​​of the current signals output by the two excitation current sampling modules. When the oil containing ferromagnetic abrasive particles passes through the excitation coil, the device can output an excitation current signal that is more obvious than that of only a single excitation circuit, thereby improving the detection sensitivity of the oil wear particle detection device.

Description

Technical Field

[0001] The invention belongs to the technical field of oil detection of a fan gearbox, and in particular relates to a differential double-coil oil wear particle detection device based on an excitation current signal. Background Art

[0002] With the rapid advancement of the global industrialization process, human demand for energy is also growing continuously. However, the reserves of traditional fossil energy are gradually decreasing. Therefore, wind energy as a renewable clean energy has been widely recognized by various countries. Due to the relatively harsh working environment of the wind turbine, failures of various components occur from time to time. Among all the components, the failure rate caused by the gearbox is the highest. During the operation of the wind turbine, the mechanical parts inside the gearbox will inevitably wear out. As time goes by, the wear state will gradually increase. If the wear of the mechanical parts is not known in time, it may cause a serious accident. When the wear inside the gearbox is serious, the gearbox needs to be disassembled and returned to the factory for repair, and the repair cost is high.

[0003] Oil detection technology can obtain the working condition information of the gearbox wear state by analyzing the specific situation of the abrasive particles in the lubricating oil in the gearbox. Therefore, through the research on oil abrasive particle detection technology, it is possible to give early warning of fan failures caused by gearbox wear and effectively avoid the occurrence of potential fan failures.

[0004] Compared with the traditional offline oil detection method, the online oil detection technology can instantly obtain the abrasive particle information in the running gearbox lubricant. On-site staff can ensure that the gearbox can maintain a good lubrication state through real-time working condition detection without dismantling the gearbox, which greatly avoids wear and tear failure, thereby improving the reliability of the gearbox, reducing maintenance, and extending the service life. Management and maintenance personnel formulate maintenance and repair strategies based on the gearbox operating status and wear status fed back by the device, which greatly reduces the consumption of human resources and saves maintenance and repair costs, which is of great significance to the scientific management and maintenance of wind turbine gearboxes.

[0005] Online oil detection technology mainly detects and analyzes the concentration, quantity, shape and material of abrasive particles in the oil by detecting the physical properties of the oil. Online detection sensors are divided into acoustic sensors, optical sensors and inductive sensors according to the detection principle. Among them, the inductive sensor uses the principle that the ferromagnetic abrasive particles in the oil will enhance the magnetic field and increase the inductance under the action of the alternating magnetic field, and detects the concentration of abrasive particles by sensing the changes in the magnetic field in the oil. Compared with other online abrasive particle detection sensors, inductive abrasive particle detection sensors stand out among many online detection technologies because of their simple structural principle, low cost, good real-time performance, easy maintenance and high sensitivity. Most of the existing inductive sensors can only indirectly characterize the concentration by counting ferromagnetic abrasive particles, and their accuracy and sensitivity are poor. Summary of the invention

[0006] Aiming at the technical problem that most of the inductive sensors in the prior art can only indirectly characterize the concentration by counting the ferromagnetic wear particles, thus having poor accuracy and sensitivity, the present invention provides a differential double-coil oil wear particle detection device based on an excitation current signal;

[0007] According to the present invention, a differential double-coil oil wear particle detection device based on an excitation current signal comprises:

[0008] The series resonant excitation circuit and the parallel resonant excitation circuit, both coils are wound around the outer wall of the oil flow pipeline to be detected, for forming a differential structure;

[0009] An excitation signal generating module, used for outputting an excitation signal to the series resonant excitation circuit and the parallel resonant excitation circuit, so as to generate an alternating magnetic field acting on the oil flow pipeline to be detected;

[0010] An excitation current sampling module, used to be connected in series to the series resonant excitation circuit or the parallel resonant excitation circuit to collect two current signals;

[0011] A differential amplifier is used to calculate the difference between the effective values ​​of the two current signals when the oil containing ferromagnetic abrasive particles passes through the excitation coil; the difference is used to eliminate the influence of external interference on the excitation current signal, and is also used to output an excitation current signal with a more obvious change compared to a single series resonant excitation circuit or a single parallel resonant excitation circuit when the oil containing ferromagnetic abrasive particles passes through the excitation coil;

[0012] A micro industrial computer, used for receiving the difference of the effective values ​​of the two current signals obtained by the differential amplifier, and then performing effective value extraction on the difference every time a preset Δt passes, so as to obtain an effective value feature extraction result C for characterizing the concentration of ferromagnetic abrasive particles contained in the oil; and also used for performing a linear fitting on the time axis for the C values ​​obtained in two Δt time periods, so as to obtain a linear slope K value for characterizing the concentration growth rate of ferromagnetic abrasive particles contained in the oil and the abnormal wear phenomenon;

[0013] The early warning module is used to send out an alarm signal when the effective value feature extraction result C used to characterize the concentration of ferromagnetic abrasive particles contained in the oil exceeds a pre-calibrated concentration threshold, or when the slope K value of the straight line used to characterize the growth rate of the concentration of ferromagnetic abrasive particles contained in the oil and the abnormal wear phenomenon exceeds a pre-calibrated wear threshold.

[0014] Preferably, the series resonant excitation circuit comprises a series resonant excitation coil, an adjustable resonant capacitor C1 and an adjustable resistor R1 connected in series, and is used to cooperate with the excitation signal generating module and the excitation current sampling module;

[0015] The series resonant excitation coil is composed of an enameled wire tightly wound on a transparent nylon pipe, and is used to generate a high-frequency alternating magnetic field, and is connected in series with an adjustable resonant capacitor C1 to form a series resonant structure. In the series resonant structure, the adjustable resonant capacitor C1 is used to adjust the capacity so that the resonant frequency f1 of the series resonant excitation circuit is slightly smaller than the excitation signal frequency f0, so that the influence of the change in abrasive concentration on the excitation current is monotonic.

[0016] When the oil containing ferromagnetic abrasive particles passes through the excitation coil, the excitation current will shift toward the direction of frequency reduction along the frequency change curve, and the series resonant excitation circuit will further deviate from the resonant state, resulting in a significant decrease in the excitation current, thereby improving the detection sensitivity of ferromagnetic abrasive particles in the oil.

[0017] Preferably, the parallel resonant excitation circuit comprises a parallel resonant excitation coil, an adjustable resonant capacitor C2 and an adjusting resistor R2 connected in parallel; and is used to cooperate with the excitation signal generating module and the excitation current sampling module;

[0018] The parallel resonant excitation coil is composed of an enameled wire tightly wound on the outside of the series resonant excitation coil, which is used to generate a high-frequency alternating magnetic field and is connected in parallel with the adjustable resonant capacitor C2 to form a parallel resonant structure. In the parallel resonant structure, the capacity of the adjustable resonant capacitor C2 is used to be adjusted so that the resonant frequency f1 of the parallel resonant excitation circuit is slightly less than the excitation signal frequency f0, so that the effect of the change in abrasive concentration on the excitation current is monotonic. When the oil containing ferromagnetic abrasives passes through the excitation coil, the excitation current will shift in the direction of frequency reduction along the frequency change curve, and the parallel resonant excitation circuit will further deviate from the resonant state, resulting in a significant increase in the excitation current, thereby improving the detection sensitivity of ferromagnetic abrasives in the oil.

[0019] Preferably, the excitation signal generating module includes a microprocessor, a DDS signal generator, a DA module, a signal conditioning circuit, an adjustable power amplifier 1, and an adjustable power amplifier 2;

[0020] A microprocessor, used for sending instructions including the amplitude and frequency of the excitation voltage signal to the DDS signal generator;

[0021] A DDS signal generator is used to decode the instruction and output the decoded excitation signal to the DA module to complete the conversion between the digital signal and the analog signal;

[0022] A signal conditioning circuit is used to switch the single-channel excitation voltage signal converted by the DA module into two-channel excitation voltage signals with the same amplitude, frequency and phase;

[0023] Adjusting the adjustable power amplifier 1 and the adjustable power amplifier 2 to output two high-frequency sinusoidal AC voltage signals with different amplitudes but the same frequency and phase to the series resonant excitation circuit and the parallel resonant excitation circuit respectively;

[0024] When pure oil without ferromagnetic abrasive particles passes through two sets of excitation coils, under the excitation of two sinusoidal alternating voltages, the excitation currents generated by the series resonant excitation circuit and the parallel resonant excitation circuit will reach the same reference value.

[0025] Preferably, the excitation current sampling module includes a precision potentiometer, a current acquisition chip, an amplifier circuit, a bandpass filter, and an effective value detection circuit;

[0026] A current acquisition chip is used to acquire the excitation current signal in the series resonant excitation circuit or the parallel resonant excitation circuit through a precision potentiometer;

[0027] an amplifier circuit, used for amplifying the excitation current signal;

[0028] A bandpass filter is used to filter out clutter and interference signals from the amplified excitation current signal, leaving an excitation current signal with the same frequency as the alternating voltage generated by the excitation signal generating module;

[0029] The effective value detection circuit is used for converting the remaining excitation current signal into an effective value.

[0030] The present invention also provides a differential double-coil oil wear particle detection method based on an excitation current signal, which is performed using the differential double-coil oil wear particle detection device based on an excitation current signal, and includes the following steps:

[0031] Step S1, winding the coils of the series resonant excitation circuit and the parallel resonant excitation circuit around the outer wall of the oil flow pipeline to be detected to form a differential structure;

[0032] Step S2, using an excitation signal generating module to output an excitation signal to the series resonant excitation circuit and the parallel resonant excitation circuit to generate an alternating magnetic field acting on the oil flow pipeline to be detected;

[0033] Step S3, using an excitation current sampling module connected in series to the series resonant excitation circuit or the parallel resonant excitation circuit to collect two current signals;

[0034] Step S4, using a differential amplifier to calculate the difference between the effective values ​​of the two current signals when the oil containing ferromagnetic abrasive particles passes through the excitation coil; the difference is used to eliminate the influence of external interference on the excitation current signal, and is also used to output an excitation current signal that is more obviously changed compared to a single series resonant excitation circuit or a single parallel resonant excitation circuit when the oil containing ferromagnetic abrasive particles passes through the excitation coil, so as to improve the detection sensitivity of the oil wear particle detection device;

[0035] Step S5, using a micro industrial computer to receive the difference in effective values ​​of the two current signals obtained by the differential amplifier, and then extracting the effective value of the difference once every preset Δt to obtain an effective value feature extraction result C for characterizing the concentration of ferromagnetic abrasive particles contained in the oil; and also performing a linear fitting on the time axis for the C values ​​obtained in the two Δt time periods to obtain a linear slope K value for characterizing the concentration growth rate of ferromagnetic abrasive particles contained in the oil and abnormal wear phenomenon;

[0036] Step S6, using the early warning module to issue an alarm signal when the effective value feature extraction result C used to characterize the concentration of ferromagnetic abrasive particles contained in the oil exceeds a preset concentration threshold, or when the slope K value of the straight line used to characterize the growth rate of the concentration of ferromagnetic abrasive particles contained in the oil and the abnormal wear phenomenon exceeds a preset wear threshold.

[0037] Preferably, the series resonant excitation circuit in step S1 includes a series resonant excitation coil, an adjustable resonant capacitor C1 and an adjustable resistor R1 connected in series, and is used to cooperate with the excitation signal generating module and the excitation current sampling module;

[0038] The parallel resonant excitation circuit includes a parallel resonant excitation coil, an adjustable resonant capacitor C2 and an adjustable resistor R2 connected in parallel; and is used to cooperate with the excitation signal generating module and the excitation current sampling module;

[0039] The step S1 also includes:

[0040] By adjusting the capacitance value of the adjustable resonant capacitor C1, the adjustable resonant capacitor C2, and the inductance value L of the excitation coil in the series resonant excitation circuit a And the inductance value L of the excitation coil in the parallel resonant excitation circuit b , ensuring that the resonant frequency f1 of the series resonant excitation circuit and the parallel resonant excitation circuit is slightly smaller than the excitation signal frequency f0, so that the effect of the change in abrasive concentration on the excitation current is monotonic.

[0041] Preferably, the excitation signal generating module in step S2 includes a microprocessor, a DDS signal generator, a DA module, a signal conditioning circuit, an adjustable power amplifier 1, and an adjustable power amplifier 2;

[0042] In step S2, the initial parameters in the microprocessor are first set, and the excitation currents generated by the series resonant excitation circuit and the parallel resonant excitation circuit are adjusted to the same reference value by adjusting the adjustable power amplifier 1 and the adjustable power amplifier 2;

[0043] The initial parameters set in the microprocessor include the amplitude A and the frequency f of the alternating voltage in the initial state, and then the excitation currents generated by the series resonant excitation circuit and the parallel resonant excitation circuit when the pure oil without ferromagnetic abrasive particles passes through the two sets of excitation coils are adjusted to the same reference value by adjusting the adjustable power amplifier 1 and the adjustable power amplifier 2;

[0044] The sampling parameters set in the excitation current sampling module include the sampling frequency f of the excitation current signal. a and sampling time interval Δt.

[0045] Preferably, the series resonant excitation circuit in step S1 includes a series resonant excitation coil, an adjustable resonant capacitor C1 and an adjustable resistor R1 connected in series, and is used to cooperate with the excitation signal generating module and the excitation current sampling module;

[0046] The parallel resonant excitation circuit includes a parallel resonant excitation coil, an adjustable resonant capacitor C2 and an adjustable resistor R2 connected in parallel; and is used to cooperate with the excitation signal generating module and the excitation current sampling module;

[0047] The step S1 further comprises:

[0048] The resistors R1 and R2 are adjusted to make the quality factor Q1 of the series resonant excitation circuit and the quality factor Q2 of the parallel resonant excitation circuit reach the maximum value. The larger the values ​​of Q1 and Q2, the steeper the curve of the excitation current changing with frequency will be, which is used to improve the detection sensitivity.

[0049] When oil containing ferromagnetic abrasive particles passes through the excitation coil, the excitation current frequency variation curve will shift toward the direction of frequency reduction, and the series and parallel resonant excitation circuits will further deviate from the resonant state. At this time, since the magnetic current frequency variation curve is steeper, the excitation current of the series resonant excitation circuit will decrease more significantly as the excitation current frequency variation curve shifts toward the direction of frequency reduction, and the excitation current of the parallel resonant excitation circuit will increase more significantly as the excitation current frequency variation curve shifts toward the direction of frequency reduction, ultimately further improving the detection sensitivity of the oil abrasive particle detection device to the concentration of ferromagnetic abrasive particles.

[0050] The theoretical basis for the conclusion that "the resistors R1 and R2 are adjusted to make the quality factor Q1 of the series resonant excitation circuit and the quality factor Q2 of the parallel resonant excitation circuit reach their maximum values, and the larger the Q1 and Q2, the steeper the curve of the excitation current changing with frequency" is as follows:

[0051] Assume that the length of the solenoid is l, the radius is r, the number of turns is N, the current passing through the solenoid is I, and the magnetic permeability of the vacuum is μ0. The magnetic induction intensity B at any point O on the axis of the solenoid is:

[0052]

[0053] Where β and α are the angles between the line connecting the left and right ends of the solenoid to point O on the axis and the axis.

[0054] It can be considered that the magnetic induction intensity B of the entire coil at any point on the axis is uniformly distributed. When the position of any point on the axis is different, its B value is also different. For the convenience of calculation, the average value can be taken.

[0055]

[0056] When the solenoid coil is air-core, the definition of inductance shows that:

[0057]

[0058] When l≥r, the above formula can be approximated as:

[0059]

[0060] When a ferromagnetic abrasive particle passes through the solenoid coil, the inductance of the part of the coil where it enters will increase due to the magnetization of the ferromagnetic abrasive particle. Assume that the radius of the ferromagnetic abrasive particle is r0 and the magnetic permeability of the ferromagnetic abrasive particle is μ r , the length of the ferromagnetic abrasive entering the coil is l0, then the inductance change is L2:

[0061]

[0062] Total inductance of a single excitation coil L:

[0063]

[0064] From formula (1-8), it can be seen that an important factor affecting the total inductance L is the magnetic permeability of the medium in the excitation coil, that is, the magnetic permeability of the fluid medium in the pipeline. Next, the relationship between abrasive concentration and magnetic permeability will be derived in detail.

[0065] When fluid flows through the excitation coil, the fluid containing ferromagnetic abrasive particles will rapidly undergo magnetization under the action of the alternating magnetic field, and the magnetized ferromagnetic abrasive particles will change the distribution of the original magnetic field in space. At this time, the ferromagnetic abrasive particles, as a magnetic medium, will generate a magnetization intensity M due to the magnetization of the magnetic field. For isotropic substances, the ratio of the magnetization intensity M to the original magnetic field intensity H is the magnetic susceptibility χ of the solution. The relationship between the three can be expressed as follows in SI (International System of Units):

[0066] M=χH (1-9)

[0067] After the ferromagnetic particles in the pipeline are magnetized, they will show magnetism and generate a magnetic field, which will increase the original magnetic induction intensity. At this time, the magnetic induction intensity B is as shown in the following formula:

[0068]

[0069] From the above formula, we know that 1+χ is the mixed magnetic permeability of the mixture of oil and ferromagnetic abrasive particles. Therefore, when the oil containing ferromagnetic abrasive particles passes through the excitation coil, the expression of the total inductance L is as follows:

[0070]

[0071] The relationship between the density of the abrasive oil and the magnetic susceptibility is derived from the following formula. The expression of the magnetic susceptibility χ is as follows: M is the molar magnetic susceptibility, M r is the relative molecular mass.

[0072]

[0073] From the above formula, we can see that the factors that affect the magnetic susceptibility of the medium are density, molar magnetic susceptibility and relative molecular mass. Since the relative molecular mass of the oil is fixed, the medium density and molar magnetic susceptibility become factors that change the magnetic susceptibility value. For oil containing ferromagnetic abrasive particles, the higher the concentration of ferromagnetic abrasive particles, the greater its density will be, and the molar magnetic susceptibility will also increase, which will lead to an increase in magnetic susceptibility, and the mixed magnetic permeability 1+χ will increase accordingly, which will eventually lead to an increase in total inductance.

[0074] The formula for the change of resonant frequency with inductance is shown as follows:

[0075]

[0076]

[0077] f1 is the resonant frequency before the inductance changes, f2 is the resonant frequency after the inductance changes, and Δf is the change in the resonant frequency. When the oil containing ferromagnetic abrasive particles passes through the excitation coil, the increase in total inductance eventually reduces the resonant frequency of the series resonant excitation circuit and the parallel resonant excitation circuit, from f1 to f2, which eventually causes the excitation current of the series resonant excitation circuit to change with frequency and the excitation current of the parallel resonant excitation circuit to change with frequency to shift in the direction of frequency reduction.

[0078] By adjusting the capacitance value of the adjustable resonant capacitor C1, the adjustable resonant capacitor C2, and the inductance value L of the excitation coil in the series resonant excitation circuit a And the inductance value L of the excitation coil in the parallel resonant excitation circuit b , ensuring that the resonant frequency f1 of the series resonant excitation circuit and the parallel resonant excitation circuit is slightly smaller than the excitation signal frequency f0, so that the effect of the change in abrasive concentration on the excitation current is monotonic.

[0079] Keeping the excitation frequency f0 unchanged, the excitation current of the series resonant excitation circuit decreases monotonically significantly in the process of the excitation current changing with frequency curve shifting toward the frequency decreasing direction, and the excitation current of the parallel resonant excitation circuit increases monotonically significantly in the process of the excitation current changing with frequency curve shifting toward the frequency decreasing direction.

[0080] The series resonance quality factor Q1 and the parallel resonance quality factor Q2 are calculated as follows:

[0081] ω=2πf0 (1-16)

[0082]

[0083] ω is the angular frequency, L ais the total inductance of the excitation coil in the series resonant excitation circuit, C1 is the adjustable resonant capacitor of the series resonant excitation, and R1 is the total inductance L of the excitation coil and the adjustable resonant capacitor C1 in the series resonant excitation circuit. a The series adjustment resistor, from the formula we can see that the smaller R1 is, the larger the quality factor is. By adjusting R1, the quality factor Q1 of the series resonant excitation circuit can reach the maximum value.

[0084]

[0085] L b is the total inductance of the excitation coil in the parallel resonant excitation circuit, C2 is the adjustable resonant capacitor of the parallel resonant excitation circuit, and R2 is the total inductance L between the adjustable resonant capacitor C2 and the excitation coil. b The parallel adjustment resistor, from the formula we can see that the larger R2 is, the larger the quality factor is. By controlling R2, the quality factor Q2 of the parallel resonant excitation circuit can reach the maximum value.

[0086] Since the increase in quality factor will make the curve of excitation current changing with frequency steeper, when the curve of excitation current changing with frequency shifts toward the direction of decreasing frequency, whether it is a series resonant excitation circuit or a parallel resonant excitation circuit, the change of excitation current will be more significant than that of a single-coil oil wear particle detection device without adding a resonant capacitor, thereby improving the sensitivity of the oil wear particle detection device, and the differential structure composed of the series resonant excitation circuit and the parallel resonant excitation circuit will further improve the detection sensitivity.

[0087] In summary, since the ferromagnetic abrasive oil is a relatively strong paramagnetic fluid medium, the increase in the concentration of ferromagnetic abrasive particles in the oil will increase the density and molar magnetic susceptibility of the abrasive oil, which will inevitably cause the magnetic susceptibility to increase and the mixed magnetic permeability to increase. 1 +χ increases, the total inductance increases, and the resonant frequency decreases, which eventually causes the excitation current to shift in the direction of frequency decrease as the frequency changes, causing the excitation current of the series resonant excitation circuit to decrease significantly and the excitation current of the parallel resonant excitation circuit to increase significantly. Similarly, the change of the excitation current when the abrasive concentration decreases can be obtained.

[0088] Due to the existence of quality factors Q1 and Q2, Q1 and Q2 can be increased by adjusting R1 and R2. The increase of Q1 and Q2 will make the curve of excitation current changing with frequency steeper. When the curve of excitation current changing with frequency shifts in the direction of frequency reduction, the change of excitation current will be more significant than before. The effective values ​​of the two excitation currents of the series resonant excitation circuit and the parallel resonant excitation circuit are subtracted to form a differential structure. The difference obtained will further amplify this change, thereby greatly improving the sensitivity of the oil wear particle detection device.

[0089] As a preference,

[0090] Step S5 includes:

[0091] During the operation of the oil wear particle detection device, the effective value data of the excitation current collected in real time by the two excitation current sampling modules are differentiated by a differential amplifier and uploaded to the micro industrial computer;

[0092] The effective value feature extraction is performed once every Δt, and the obtained effective value feature extraction result C is used to characterize the concentration of ferromagnetic abrasive particles contained in the oil;

[0093] The C values ​​obtained in the two Δt time periods are linearly fitted on the time axis, and the linear slope K value obtained is used to characterize the concentration growth rate of ferromagnetic abrasive particles contained in the oil and the abnormal wear phenomenon. Different K values ​​represent different growth rates and abnormal wear.

[0094] The characterization value C is used to calibrate different abrasive concentrations, and the characterization value K is used to calibrate different abrasive concentration growth rates and wear states, thereby obtaining a database of the characterization value C and the characterization value K;

[0095] The micro industrial computer calculates the characterization value K and the characterization value C in real time according to the collected excitation current signal, and obtains the concentration of ferromagnetic abrasive particles contained in the oil represented by the characterization value C and the characterization value K, the growth rate of the abrasive particle concentration, and the abnormal wear inside the gearbox by accessing the database.

[0096] Compared with the prior art, the present invention has the following beneficial effects:

[0097] 1. During use of the present invention, when ferromagnetic abrasive particles pass through the excitation coil, the excitation current of the series resonant excitation circuit is significantly reduced, and the excitation current of the parallel resonant excitation circuit is significantly increased. The current change directions of the two resonant excitation circuits are opposite, and the two can form a differential structure. The effective values ​​of the current signals output by the two excitation current sampling modules are subtracted by a differential amplifier. On the one hand, the difference can eliminate the influence of external electromagnetic fields, temperature fields and other interferences on the excitation current signal. On the other hand, when the oil containing ferromagnetic abrasive particles passes through the excitation coil, the device can output an excitation current signal that changes more significantly than that of only a single series resonant excitation circuit or a single parallel resonant excitation circuit, thereby improving the detection sensitivity of the oil abrasive particle detection device.

[0098] 2. The present invention connects two excitation current sampling modules in series in the parallel resonant excitation circuit and the series resonant excitation circuit respectively, so that the current signal of the excitation circuit under the action of the alternating voltage is collected in real time, and the effective values ​​of the two current signals are subtracted by the differential amplifier and the difference is transmitted to the micro industrial computer for time-frequency domain analysis, feature extraction and other data processing operations. The micro industrial computer retrieves the database to determine whether the concentration of ferromagnetic abrasive particles in the oil exceeds the set threshold and determines whether abnormal wear occurs inside the gearbox according to the growth rate of the abrasive particle concentration. If the threshold is exceeded or abnormal wear occurs, an alarm signal is issued.

[0099] 3. The present invention uses an excitation signal generating module, and the DDS signal generator decodes the instruction sent by the processor and outputs the decoded excitation signal to the DA module to complete the conversion between digital signals and analog signals. Subsequently, the signal conditioning circuit is used to switch the single-channel excitation voltage signal converted by the DA module into two-channel excitation voltage signals with the same amplitude, frequency and phase, and then output two high-frequency sinusoidal AC voltage signals with different amplitudes but the same frequency and phase.

[0100] 4. The present invention uses a current acquisition chip to collect the excitation current signal in the circuit through a precision potentiometer, then amplifies the signal through an amplifier circuit, and then passes through a bandpass filter to filter out clutter and interference signals, leaving the excitation current signal with the same frequency as the alternating voltage generated by the excitation signal generating module, and finally converts the amplified excitation current signal into an effective value through an effective value detection circuit.

[0101] 5. The present invention forms a series or parallel resonant excitation structure by connecting the excitation coil and the adjustable resonant capacitor in series or in parallel. By adjusting the inductance of the excitation coil and the capacity of the adjustable resonant capacitor, the resonant frequency of the resonant excitation circuit is ensured to be slightly less than the excitation signal frequency, so that the influence of the change in abrasive concentration on the excitation current is monotonic. When the oil containing ferromagnetic abrasive passes through the excitation coil, the excitation current will shift in the direction of frequency reduction along the frequency change curve, and the series-parallel resonant excitation circuit will further deviate from the resonant state, causing a significant change in the excitation current.

[0102] 6. The present invention adjusts the excitation current generated by the series resonant excitation circuit and the parallel resonant excitation circuit to the same reference value when the pure oil without ferromagnetic abrasive particles passes through two sets of excitation coils by adjusting the adjustable power amplifier 1 and the adjustable power amplifier 2. BRIEF DESCRIPTION OF THE DRAWINGS

[0103] Figure 1 A schematic structural diagram of a differential dual-coil oil wear particle detection device based on an excitation current signal provided by an embodiment of the present invention;

[0104] Figure 2 for Figure 1Schematic diagram of the structure of the excitation coil;

[0105] Figure 3 for Figure 1 Schematic diagram of the structure of the excitation signal generation module

[0106] Figure 4 for Figure 1 Schematic diagram of the structure of the current sampling module

[0107] Figure 5 Flow chart of excitation current signal processing in an embodiment of the present invention. DETAILED DESCRIPTION

[0108] To make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be described clearly and completely in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them.

[0109] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents some embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0110] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features and technical solutions therein can be combined with each other. It should be noted that similar numbers and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0111] like Figure 1 As shown, the differential double-coil oil wear particle detection device based on the excitation current signal includes a series resonant excitation circuit, a parallel resonant excitation circuit, an excitation signal generation module, an excitation current sampling module, a differential amplifier and a micro industrial computer. The two excitation current sampling modules are respectively connected in series in the parallel resonant excitation circuit and the series resonant excitation circuit to collect the current signal of the excitation circuit under the action of the alternating voltage in real time. Through the differential amplifier, the difference between the effective values ​​of the two current signals is transmitted to the micro industrial computer for time-frequency domain analysis, feature extraction and other data processing operations. The micro industrial computer determines whether the concentration of ferromagnetic abrasive particles in the oil exceeds the set threshold value based on the processing results of the excitation current signal data collected on site, and judges whether abnormal wear occurs inside the gearbox based on the increase rate of the abrasive particle concentration. When the threshold value is exceeded or abnormal wear occurs, an alarm signal is issued.

[0112] like Figure 2As shown, the excitation coil is composed of a series resonant excitation coil and a parallel resonant excitation coil, which is used to generate a high-frequency alternating magnetic field. The series and parallel resonant excitation coils are wound outside the oil flow pipeline in the form of a single layer of several turns, and the parallel resonant excitation coil is wound outside the series resonant excitation coil. The input end of the excitation coil winding is connected to the output end of the excitation signal generating module, which is used to receive a high-frequency sinusoidal AC voltage signal and generate an alternating magnetic field acting on the oil flow pipeline. The output end of the excitation coil winding is connected in series with the input end of the excitation current sampling module, and the excitation current reflecting the concentration of ferromagnetic abrasive particles in the oil can be collected through the current sampling module. In addition, the series resonant excitation coil and the adjustable resonant capacitor C1 are connected in series, and the parallel resonant excitation coil and the adjustable resonant capacitor C2 are connected in parallel. By adjusting the values ​​of the adjustable resonant capacitor C1 and the adjustable resonant capacitor C2, it can be ensured that the resonant frequency is slightly less than the excitation signal frequency, so that the change of the abrasive particle concentration has a monotonic effect on the excitation current. When the ferromagnetic abrasive oil passes through the excitation coil, the excitation current will shift in the direction of frequency reduction along the frequency change curve, and the resonant excitation circuit will further deviate from the resonant state, causing the excitation current to change significantly.

[0113] like Figure 3 As shown, the excitation signal generating module includes a microprocessor, a DDS signal generator, a DA module, a signal conditioning circuit, an adjustable power amplifier circuit 1, and an adjustable power amplifier circuit 2. The microprocessor is used to send instructions containing the amplitude and frequency of the excitation voltage signal to the DDS signal generator, and the DDS signal generator decodes the instructions and outputs the decoded excitation signal to the DA module to complete the conversion between digital signals and analog signals. Subsequently, the signal conditioning circuit is used to switch the single excitation voltage signal converted by the DA module into two excitation voltage signals with the same amplitude, frequency, and phase, and the adjustable power amplifier 1 and the adjustable power amplifier 2 are adjusted to output two high-frequency sinusoidal AC voltage signals with different amplitudes but the same frequency and phase. When pure oil without ferromagnetic abrasive particles passes through two sets of excitation coils, under the excitation of the two sinusoidal alternating voltages, the excitation currents generated by the series resonant excitation circuit and the parallel resonant excitation circuit will reach the same reference value.

[0114] like Figure 4 As shown, the excitation current sampling module includes a precision potentiometer, a current acquisition chip, an amplifier circuit, a bandpass filter, and an effective value detection circuit. First, the current acquisition chip acquires the excitation current signal in the circuit through the precision potentiometer, then amplifies the signal through the amplifier circuit, and then passes through the bandpass filter to filter out clutter and interference signals, leaving the excitation current signal with the same frequency as the alternating voltage generated by the excitation signal generation module, and finally converts the amplified excitation current signal into an effective value through the effective value detection circuit.

[0115] like Figure 5As shown in the figure, the excitation current signal processing process can be specifically described as follows: before the oil wear particle detection device starts running, the characterization value of the ferromagnetic abrasive particle concentration contained in the oil is set to C, its initial value is set to 0, and the total number of cycles is set to 2. During the operation, the original data of the effective value of the excitation current collected in real time by the two excitation current sampling modules are subtracted by a differential amplifier and uploaded to the micro-industrial computer. The effective value feature extraction is performed once every Δt, and the effective value feature extraction result C obtained can characterize the concentration of ferromagnetic abrasive particles contained in the oil. Then, the number of cycles is increased by 1, and the above steps are repeated until the preset number of cycles is reached 2 times. The C value outputted twice is linearly fitted on the time axis to obtain the slope K to characterize the abrasive particle concentration growth rate and abnormal wear, and the cycle ends at this time.

[0116] Combined with the differential double-coil oil wear particle detection method based on the excitation current signal, the specific implementation steps of the differential double-coil oil wear particle detection device are introduced:

[0117] Step 1) The initial parameters set in the microprocessor include the amplitude A and frequency f of the alternating voltage in the initial state, where A is 5Vpp and f is 2MHz. The sampling parameters set in the excitation current sampling module include the sampling frequency f of the excitation current signal. a And the sampling time interval Δt, the sampling frequency f of the current signal a The excitation current generated by the series resonant excitation circuit and the parallel resonant excitation circuit when the pure oil without ferromagnetic abrasive particles passes through the two sets of excitation coils is adjusted to 100mA. (A, f, f can be adjusted according to the specific working conditions.) a , Δt is adjusted appropriately).

[0118] Step 2) By adjusting the capacitance value of the adjustable resonant capacitor C1, the adjustable resonant capacitor C2, and the inductance value L of the excitation coil in the series resonant excitation circuit a And the inductance value L of the excitation coil in the parallel resonant excitation circuit b , ensuring that the resonant frequency f1 of the series resonant excitation circuit and the parallel resonant excitation circuit is slightly smaller than the excitation signal frequency f0, so that the effect of the change in abrasive concentration on the excitation current is monotonic.

[0119] Step 3) Adjust the resistors R1 and R2 to make the quality factor Q1 of the series resonant excitation circuit and the quality factor Q2 of the parallel resonant excitation circuit reach the maximum value. The larger the Q1 and Q2 are, the steeper the curve of the excitation current changing with frequency will be. When the oil containing ferromagnetic abrasive particles passes through the excitation coil, the curve of the excitation current changing with frequency will shift in the direction of frequency reduction, and the series and parallel resonant excitation circuits will further deviate from the resonant state. At this time, since the curve of the magnetic current changing with frequency is steeper, when the curve of the excitation current changing with frequency shifts in the direction of frequency reduction, the change of the excitation current will be more significant than before. The difference between the effective values ​​of the two excitation currents of the series resonant excitation circuit and the parallel resonant excitation circuit can form a differential structure, and the difference obtained will further amplify this change, thereby greatly improving the sensitivity of the oil abrasive particle detection device.

[0120] Furthermore, the theoretical basis for the conclusion in step 3 of "adjusting the resistors R1 and R2 so that the quality factor Q1 of the series resonant excitation circuit and the quality factor Q2 of the parallel resonant excitation circuit reach the maximum value, and the larger the values ​​of Q1 and Q2, the steeper the curve of the excitation current changing with frequency" is as follows:

[0121] Assume that the length of the solenoid is l, the radius is r, the number of turns is N, the current passing through the solenoid is I, and the magnetic permeability of the vacuum is μ0. The magnetic induction intensity B at any point O on the axis of the solenoid is:

[0122]

[0123] Where β and α are the angles between the line connecting the left and right ends of the solenoid to point O on the axis and the axis.

[0124] It can be considered that the magnetic induction intensity B of the entire coil at any point on the axis is uniformly distributed. When the position of any point on the axis is different, its B value is also different. For the convenience of calculation, the average value can be taken.

[0125]

[0126] When the solenoid coil is air-core, the definition of inductance shows that:

[0127]

[0128] When l≥r, the above formula can be approximated as:

[0129]

[0130] When a ferromagnetic abrasive particle passes through the solenoid coil, the inductance of the part of the coil where it enters will increase due to the magnetization of the ferromagnetic abrasive particle. Assume that the radius of the ferromagnetic abrasive particle is r0 and the magnetic permeability of the ferromagnetic abrasive particle is μ r, the length of the ferromagnetic abrasive entering the coil is l0, then the inductance change is L2:

[0131]

[0132] Total inductance of a single excitation coil L:

[0133]

[0134] From formula (1-8), it can be seen that an important factor affecting the total inductance L is the magnetic permeability of the medium in the excitation coil, that is, the magnetic permeability of the fluid medium in the pipeline. Next, the relationship between abrasive concentration and magnetic permeability will be derived in detail.

[0135] When fluid flows through the excitation coil, the fluid containing ferromagnetic abrasive particles will rapidly undergo magnetization under the action of the alternating magnetic field, and the magnetized ferromagnetic abrasive particles will change the distribution of the original magnetic field in space. At this time, the ferromagnetic abrasive particles, as a magnetic medium, will generate a magnetization intensity M due to the magnetization of the magnetic field. For isotropic substances, the ratio of the magnetization intensity M to the original magnetic field intensity H is the magnetic susceptibility χ of the solution. The relationship between the three can be expressed as follows in SI (International System of Units):

[0136] M=χH(1-9)

[0137] After the ferromagnetic particles in the pipeline are magnetized, they will show magnetism and generate a magnetic field, which will increase the original magnetic induction intensity. At this time, the magnetic induction intensity B is as shown in the following formula:

[0138]

[0139] From the above formula, we know that 1+χ is the mixed magnetic permeability of the mixture of oil and ferromagnetic abrasive particles. Therefore, when the oil containing ferromagnetic abrasive particles passes through the excitation coil, the expression of the total inductance L is as follows:

[0140]

[0141] The relationship between the density of the abrasive oil and the magnetic susceptibility is derived from the following formula. The expression of the magnetic susceptibility χ is as follows: M is the molar magnetic susceptibility, M r is the relative molecular mass.

[0142]

[0143] From the above formula, we can see that the factors that affect the magnetic susceptibility of the medium are density, molar magnetic susceptibility and relative molecular mass. Since the relative molecular mass of the oil is fixed, the medium density and molar magnetic susceptibility become factors that change the magnetic susceptibility value. For oil containing ferromagnetic abrasive particles, the higher the concentration of ferromagnetic abrasive particles, the greater its density will be, and the molar magnetic susceptibility will also increase, which will lead to an increase in magnetic susceptibility, and the mixed magnetic permeability 1+χ will increase accordingly, which will eventually lead to an increase in total inductance.

[0144] The formula for the change of resonant frequency with inductance is shown as follows:

[0145]

[0146] f1 is the resonant frequency before the inductance changes, f2 is the resonant frequency after the inductance changes, and Δf is the change in the resonant frequency. When the oil containing ferromagnetic abrasive particles passes through the excitation coil, the increase in total inductance eventually reduces the resonant frequency of the series resonant excitation circuit and the parallel resonant excitation circuit, from f1 to f2, which eventually causes the excitation current of the series resonant excitation circuit to change with frequency and the excitation current of the parallel resonant excitation circuit to change with frequency to shift in the direction of frequency reduction.

[0147] By adjusting the capacitance value of the adjustable resonant capacitor C1, the adjustable resonant capacitor C2, and the inductance value L of the excitation coil in the series resonant excitation circuit a And the inductance value L of the excitation coil in the parallel resonant excitation circuit b , ensuring that the resonant frequency f1 of the series resonant excitation circuit and the parallel resonant excitation circuit is slightly smaller than the excitation signal frequency f0, so that the effect of the change in abrasive concentration on the excitation current is monotonic.

[0148] Keeping the excitation frequency f0 unchanged, the excitation current of the series resonant excitation circuit decreases monotonically significantly in the process of the excitation current changing with frequency curve shifting toward the frequency decreasing direction, and the excitation current of the parallel resonant excitation circuit increases monotonically significantly in the process of the excitation current changing with frequency curve shifting toward the frequency decreasing direction.

[0149] The series resonance quality factor Q1 and the parallel resonance quality factor Q2 are calculated as follows:

[0150] ω=2πf0 (1-16)

[0151]

[0152] ω is the angular frequency, L a is the total inductance of the excitation coil in the series resonant excitation circuit, C1 is the adjustable resonant capacitor of the series resonant excitation circuit, and R1 is the total inductance L of the excitation coil and the adjustable resonant capacitor C1 in the series resonant excitation circuit. aThe series adjustment resistor, from the formula we can see that the smaller R1 is, the larger the quality factor is. By adjusting R1, the quality factor Q1 of the series resonant excitation circuit can reach the maximum value.

[0153]

[0154] L b is the total inductance of the excitation coil in the parallel resonant excitation circuit, C2 is the adjustable resonant capacitor of the parallel resonant excitation circuit, and R2 is the total inductance L between the adjustable resonant C2 and the excitation coil. b The parallel adjustment resistor, from the formula we can see that the larger R2 is, the larger the quality factor is. By controlling R2, the quality factor Q2 of the parallel resonant excitation circuit can reach the maximum value.

[0155] Since the increase in quality factor will make the curve of excitation current changing with frequency steeper, when the curve of excitation current changing with frequency shifts toward the direction of decreasing frequency, whether it is a series resonant excitation circuit or a parallel resonant excitation circuit, the change of excitation current will be more significant than that of a single-coil oil wear particle detection device without adding a resonant capacitor, thereby improving the sensitivity of the oil wear particle detection device, and the differential structure composed of the series resonant excitation circuit and the parallel resonant excitation circuit will further improve the detection sensitivity.

[0156] In summary, since the ferromagnetic abrasive oil is a relatively strong paramagnetic fluid medium, the increase in the concentration of ferromagnetic abrasive in the oil will increase the density and molar magnetic susceptibility of the abrasive oil, which will inevitably cause the magnetic susceptibility to increase, the mixed magnetic permeability 1+χ to increase, the total inductance to increase, and the resonant frequency to decrease, which will eventually cause the excitation current to shift in the direction of frequency decrease as the frequency changes, thereby causing the excitation current of the series resonant excitation circuit to decrease significantly and the excitation current of the parallel resonant excitation circuit to increase significantly. Similarly, the change of the excitation current when the abrasive concentration decreases can be obtained.

[0157] Due to the existence of quality factors Q1 and Q2, Q1 and Q2 can be increased by adjusting R1 and R2. The increase of Q1 and Q2 will make the curve of excitation current changing with frequency steeper. When the curve of excitation current changing with frequency shifts in the direction of frequency reduction, the change of excitation current will be more significant than before. The effective values ​​of the two excitation currents of the series resonant excitation circuit and the parallel resonant excitation circuit are subtracted to form a differential structure. The difference obtained will further amplify this change, thereby greatly improving the sensitivity of the oil wear particle detection device.

[0158] Step 4) During the operation of the oil wear particle detection device, the excitation current effective value data collected in real time by the two excitation current sampling modules are differentiated by a differential amplifier and uploaded to the micro industrial computer. The micro industrial computer performs effective value feature extraction once every Δt, and the effective value feature extraction result C obtained can characterize the concentration of ferromagnetic abrasive particles contained in the oil. The C values ​​obtained in the two Δt time periods are linearly fitted on the time axis, and the linear slope K value obtained can characterize the concentration growth rate of ferromagnetic abrasive particles contained in the oil and abnormal wear phenomenon.

[0159] Step 5) Establish a database, obtain the characterization value through data collection, calibrate different abrasive concentrations with the characterization value C, calibrate different abrasive concentration growth rates and wear states with the characterization value K, and obtain a database about the characterization value C and the characterization value K. At the industrial site, the micro-industrial computer calculates the characterization value K and the characterization value C in real time according to the collected excitation current signal, and obtains the concentration of ferromagnetic abrasive contained in the oil represented by the characterization value C and the characterization value K, the growth rate of the abrasive concentration, and the abnormal wear inside the gearbox by calling the database.

[0160] The above embodiments are only used to illustrate the present invention, rather than to limit the technical solutions described therein. Although the above embodiments are described in detail in this specification, the present invention is not limited to the above specific implementation modes, and therefore any technical solutions and improvements thereof that are modified or equivalently substituted for the present invention but do not depart from the scope of the present invention are all included in the scope of the claims of the present invention.

[0161] It is easy to understand that those skilled in the art can combine, split, reorganize, etc. the embodiments of the present application to obtain other embodiments based on one or several embodiments provided in the present application, and these embodiments do not exceed the protection scope of the present application.

[0162] The present invention and its implementation methods are described schematically above, and the description is not restrictive. The embodiments shown in the embodiments are only part of the implementation methods of the present invention, and the actual structure is not limited thereto. Therefore, if a person skilled in the art is inspired by the embodiments and designs a structure and an implementation method similar to the technical solution without creativity without departing from the purpose of the invention, they should all fall within the protection scope of the present invention.

Claims

1. A differential double-coil oil wear particle detection device based on excitation current signal, characterized in that: include: The series resonant excitation circuit and the parallel resonant excitation circuit, both coils are wound around the outer wall of the oil flow pipe to be detected, for forming a differential structure; and the parallel resonant excitation coil is wound around the outside of the series resonant excitation coil; An excitation signal generating module, used for outputting an excitation signal to the series resonant excitation circuit and the parallel resonant excitation circuit, so as to generate an alternating magnetic field acting on the oil flow pipeline to be detected; An excitation current sampling module, used to be connected in series to the series resonant excitation circuit or the parallel resonant excitation circuit to collect two current signals; A differential amplifier is used to calculate the difference between the effective values ​​of the two current signals when the oil containing ferromagnetic abrasive particles passes through the excitation coil; the difference is used to eliminate the influence of external interference on the excitation current signal, and is also used to output an excitation current signal with a more obvious change compared to a single series resonant excitation circuit or a single parallel resonant excitation circuit when the oil containing ferromagnetic abrasive particles passes through the excitation coil; A micro industrial computer, used for receiving the difference of the effective values ​​of the two current signals obtained by the differential amplifier, and then performing effective value extraction on the difference every time a preset Δt passes, so as to obtain an effective value feature extraction result C for characterizing the concentration of ferromagnetic abrasive particles contained in the oil; and also used for performing a linear fitting on the time axis for the C values ​​obtained in two Δt time periods, so as to obtain a linear slope K value for characterizing the concentration growth rate of ferromagnetic abrasive particles contained in the oil and the abnormal wear phenomenon; The early warning module is used to send out an alarm signal when the effective value feature extraction result C used to characterize the concentration of ferromagnetic abrasive particles contained in the oil exceeds a pre-calibrated concentration threshold, or when the slope K value of the straight line used to characterize the growth rate of the concentration of ferromagnetic abrasive particles contained in the oil and the abnormal wear phenomenon exceeds a pre-calibrated wear threshold.

2. The differential double-coil oil wear particle detection device based on excitation current signal according to claim 1, characterized in that: The series resonant excitation circuit includes a series resonant excitation coil, an adjustable resonant capacitor C1 and an adjustable resistor R1 connected in series, and is used to cooperate with the excitation signal generating module and the excitation current sampling module; The series resonant excitation coil is composed of enameled wire tightly wound on a transparent nylon pipe, which is used to generate a high-frequency alternating magnetic field and is connected in series with an adjustable resonant capacitor C1 to form a series resonant structure. In the series resonant structure, the capacity of the adjustable resonant capacitor C1 is used to be adjusted so that the resonant frequency f1 of the series resonant structure is slightly smaller than the excitation signal frequency f0, so that the effect of the change in abrasive concentration on the excitation current is monotonic.

3. The differential double-coil oil wear particle detection device based on excitation current signal according to claim 1, characterized in that: The parallel resonant excitation circuit includes a parallel resonant excitation coil, an adjustable resonant capacitor C2 and an adjustable resistor R2 connected in parallel; and is used to cooperate with the excitation signal generating module and the excitation current sampling module; The parallel resonant excitation coil is composed of an enameled wire tightly wound on the outside of the series resonant excitation coil, which is used to generate a high-frequency alternating magnetic field and is connected in parallel with the adjustable resonant capacitor C2 to form a parallel resonant structure. In the parallel resonant structure, the capacity of the adjustable resonant capacitor C2 is used to be adjusted so that the resonant frequency f1 of the parallel resonant excitation circuit is slightly smaller than the excitation signal frequency f0, so that the effect of the change in abrasive concentration on the excitation current is monotonic.

4. The differential double-coil oil wear particle detection device based on excitation current signal according to claim 1, characterized in that: The excitation signal generating module includes a microprocessor, a DDS signal generator, a DA module, a signal conditioning circuit, an adjustable power amplifier 1, and an adjustable power amplifier 2; A microprocessor, used for sending instructions including the amplitude and frequency of the excitation voltage signal to the DDS signal generator; A DDS signal generator is used to decode the instruction and output the decoded excitation signal to the DA module to complete the conversion between the digital signal and the analog signal; A signal conditioning circuit is used to switch the single-channel excitation voltage signal converted by the DA module into two-channel excitation voltage signals with the same amplitude, frequency and phase; Adjusting the adjustable power amplifier 1 and the adjustable power amplifier 2 to output two high-frequency sinusoidal AC voltage signals with different amplitudes but the same frequency and phase to the series resonant excitation circuit and the parallel resonant excitation circuit respectively; When pure oil without ferromagnetic abrasive particles passes through two sets of excitation coils, under the excitation of two sinusoidal alternating voltages, the excitation currents generated by the series resonant excitation circuit and the parallel resonant excitation circuit will reach the same reference value.

5. The differential double-coil oil wear particle detection device based on excitation current signal according to claim 4, characterized in that: The excitation current sampling module includes a precision potentiometer, a current acquisition chip, an amplifier circuit, a bandpass filter, and an effective value detection circuit; A current acquisition chip is used to acquire the excitation current signal in the series resonant excitation circuit or the parallel resonant excitation circuit through a precision potentiometer; an amplifier circuit, used for amplifying the excitation current signal; A bandpass filter is used to filter out clutter and interference signals from the amplified excitation current signal, leaving an excitation current signal with the same frequency as the alternating voltage generated by the excitation signal generating module; The effective value detection circuit is used for converting the remaining excitation current signal into an effective value.

6. A differential double-coil oil wear particle detection method based on excitation current signal, characterized in that: The method is carried out by using a differential double-coil oil wear particle detection device based on an excitation current signal as described in any one of claims 1 to 5, which comprises the following steps: Step S1, winding the coils of the series resonant excitation circuit and the parallel resonant excitation circuit around the outer wall of the oil flow pipeline to be detected to form a differential structure; Step S2, using an excitation signal generating module to output an excitation signal to the series resonant excitation circuit and the parallel resonant excitation circuit to generate an alternating magnetic field acting on the oil flow pipeline to be detected; Step S3, using an excitation current sampling module connected in series to the series resonant excitation circuit or the parallel resonant excitation circuit to collect two current signals; Step S4, using a differential amplifier to calculate the difference between the effective values ​​of the two current signals when the oil containing ferromagnetic abrasive particles passes through the excitation coil; the difference is used to eliminate the influence of external interference on the excitation current signal, and is also used to output an excitation current signal that is more obviously changed compared to a single series resonant excitation circuit or a single parallel resonant excitation circuit when the oil containing ferromagnetic abrasive particles passes through the excitation coil, so as to improve the detection sensitivity of the oil wear particle detection device; Step S5, using a micro industrial computer to receive the difference in effective values ​​of the two current signals obtained by the differential amplifier, and then extracting the effective value of the difference once every preset Δt to obtain an effective value feature extraction result C for characterizing the concentration of ferromagnetic abrasive particles contained in the oil; and also performing a linear fitting on the time axis for the C values ​​obtained in the two Δt time periods to obtain a linear slope K value for characterizing the concentration growth rate of ferromagnetic abrasive particles contained in the oil and abnormal wear phenomenon; Step S6, using the early warning module to issue an alarm signal when the effective value feature extraction result C used to characterize the concentration of ferromagnetic abrasive particles contained in the oil exceeds a preset concentration threshold, or when the slope K value of the straight line used to characterize the growth rate of the concentration of ferromagnetic abrasive particles contained in the oil and the abnormal wear phenomenon exceeds a preset wear threshold.

7. The differential double-coil oil wear particle detection method based on excitation current signal according to claim 6, characterized in that: The series resonant excitation circuit in step S1 includes a series resonant excitation coil, an adjustable resonant capacitor C1 and an adjustable resistor R1 connected in series, and is used to cooperate with the excitation signal generating module and the excitation current sampling module; The parallel resonant excitation circuit includes a parallel resonant excitation coil, an adjustable resonant capacitor C2 and an adjustable resistor R2 connected in parallel; and is used to cooperate with the excitation signal generating module and the excitation current sampling module; The step S1 also includes: By adjusting the capacitance value of the adjustable resonant capacitor C1, the adjustable resonant capacitor C2, and the inductance value L of the excitation coil in the series resonant excitation circuit a And the inductance value L of the excitation coil in the parallel resonant excitation circuit b , ensuring that the resonant frequency f1 of the series resonant excitation circuit and the parallel resonant excitation circuit is slightly smaller than the excitation signal frequency f0, so that the effect of the change in abrasive concentration on the excitation current is monotonic.

8. The differential double-coil oil wear particle detection method based on excitation current signal according to claim 6, characterized in that: The excitation signal generating module in step S2 includes a microprocessor, a DDS signal generator, a DA module, a signal conditioning circuit, an adjustable power amplifier 1, and an adjustable power amplifier 2; In step S2, the initial parameters in the microprocessor are first set, and the excitation currents generated by the series resonant excitation circuit and the parallel resonant excitation circuit are adjusted to the same reference value by adjusting the adjustable power amplifier 1 and the adjustable power amplifier 2; The initial parameters set in the microprocessor include the amplitude A and the frequency f of the alternating voltage in the initial state, and then the excitation currents generated by the series resonant excitation circuit and the parallel resonant excitation circuit when the pure oil without ferromagnetic abrasive particles passes through the two sets of excitation coils are adjusted to the same reference value by adjusting the adjustable power amplifier 1 and the adjustable power amplifier 2; The sampling parameters set in the excitation current sampling module include the sampling frequency f of the excitation current signal. a and sampling time interval Δt.

9. The differential double-coil oil wear particle detection method based on excitation current signal according to claim 6, characterized in that: The series resonant excitation circuit in step S1 includes a series resonant excitation coil, an adjustable resonant capacitor C1 and an adjustable resistor R1 connected in series, and is used to cooperate with the excitation signal generating module and the excitation current sampling module; The parallel resonant excitation circuit comprises a parallel resonant excitation coil, an adjustable resonant capacitor C2 and an adjustable resistor R2 connected in parallel; And used to cooperate with the excitation signal generating module and the excitation current sampling module; The step S1 further comprises: The resistors R1 and R2 are adjusted to make the quality factor Q1 of the series resonant excitation circuit and the quality factor Q2 of the parallel resonant excitation circuit reach the maximum value. The larger the values ​​of Q1 and C2, the steeper the curve of the excitation current changing with frequency will be, which is used to improve the detection sensitivity.

10. The differential double-coil oil wear particle detection method based on excitation current signal according to claim 6, characterized in that: Step S5 includes: During the operation of the oil wear particle detection device, the effective value data of the excitation current collected in real time by the two excitation current sampling modules are differentiated by a differential amplifier and uploaded to the micro industrial computer; The effective value feature extraction is performed once every Δt, and the obtained effective value feature extraction result C is used to characterize the concentration of ferromagnetic abrasive particles contained in the oil; The C values ​​obtained in the two Δt time periods are linearly fitted on the time axis, and the linear slope K value obtained is used to characterize the concentration growth rate of ferromagnetic abrasive particles contained in the oil and the abnormal wear phenomenon. Different K values ​​represent different growth rates and abnormal wear. The characterization value C is used to calibrate different abrasive concentrations, and the characterization value K is used to calibrate different abrasive concentration growth rates and wear states, thereby obtaining a database of the characterization value C and the characterization value K; The micro industrial computer calculates the characterization value K and the characterization value C in real time according to the collected excitation current signal, and obtains the concentration of ferromagnetic abrasive particles contained in the oil represented by the characterization value C and the characterization value K, the growth rate of the abrasive particle concentration, and the abnormal wear inside the gearbox by accessing the database.

Images