A method of analyzing the effect of metal particle velocity on voltage signals in an inductive bridge

Abstract

This invention provides a method for analyzing the influence of metal particle velocity on voltage signals in an inductive bridge circuit. Utilizing the principle of electromagnetic induction, a lead screw and guide rail device controls the metal particles. When the metal particles pass through the induction coil in the inductive bridge circuit at different velocities, their inductive reactance changes. The voltage generated by the two arms of the bridge circuit has a voltage difference. These two voltages are rectified by the primary detection circuit module into two DC pulsating voltage signals. These two DC pulse voltage signals are filtered to remove high-frequency noise signals mixed in with the particle signal, then differentially amplified and filtered again by a terminal filter, thereby generating a differential voltage induced by the particles. The voltage data is acquired by a data acquisition card and displayed on a computer terminal for voltage signals generated by different particle velocities. This invention can analyze the influence mechanism and characteristics of different particle flow velocities and the corresponding differential voltage signals, providing theoretical support and technical assistance for improving the throughput of online oil detection.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil condition monitoring, in particular to a method for analyzing the influence of metal particle speed on voltage signal in an inductive bridge. BACKGROUND

[0002] Oil is an essential part of large mechanical systems and hydraulic systems. Hydraulic oil and lubricating oil, two types of working oil, are widely used in aerospace, automobile manufacturing, agricultural machinery, shipbuilding industry, metallurgy and other mechanical equipment, which have the functions of lubrication, cooling, sealing, cleaning and power transmission. However, during the long-term operation of mechanical equipment, especially in rotating machinery, friction between parts will cause phenomena such as abrasive wear. These worn metal particles flow into the oil, leading to the failure of the working oil, and thus affecting the normal operation of the mechanical equipment. In severe cases, it may cause equipment failure, economic loss and even endanger the safety of workers. Therefore, monitoring the working condition of oil to obtain relevant information parameters for the normal operation of the equipment can provide data support for fault diagnosis and remaining useful life prediction of mechanical equipment, and realize the health management of related equipment, which has extremely important research significance for predicting hidden safety hazards and providing safety protection.

[0003] The commonly used online oil condition monitoring methods at present include optical detection method, acoustic detection method, capacitance detection method and inductance detection method, etc. Among them, the inductive oil particle detection method has low cost, high sensitivity, easy integration and can distinguish ferromagnetic metal particles from non-ferromagnetic metal particles, but it is always weak in improving oil detection flux. The common method to improve oil detection flux is to optimize the sensor structure, such as increasing the size of oil channel, setting multiple oil channels or ring-shaped oil channels, etc. Although the above-mentioned methods of increasing size or oil channel can significantly improve the oil detection flux, they will also reduce the detection sensitivity of the sensor, causing some detection signals to be affected by noise signals, and the detection effect is seriously decreased.

[0004] Increasing the sampling speed of the oil to be detected is a method to increase the oil detection flux. However, the increase of the speed of the oil will also increase the speed of the metal particles. The movement speed of the metal particles that is too large or too small will affect the size of the detection signal, reduce the detection sensitivity of the sensor, and cause the detection effect to be seriously decreased. The specific mechanism of the influence of the movement speed of the metal particles on the detection signal is still rarely studied. SUMMARY

[0005] Based on the technical problems mentioned in the background section, this invention proposes an analytical method for studying the influence of metal particle velocity on the voltage signal in an inductive bridge. It is mainly applied to the detection of metal and non-metal particles in oil condition monitoring. Its function is to, under laboratory conditions, construct an inductive bridge detection circuit and, when metal particles pass through the induction coil in the inductive bridge at different velocities, analyze the relationship between the change in voltage signal amplitude and particle velocity based on the differential voltage signal data generated by the two arms of the bridge to explore the influence of velocity changes, thereby achieving the goal of improving detection sensitivity while increasing velocity.

[0006] The technical means employed in this invention are as follows:

[0007] A method for analyzing the effect of metal particle velocity on the voltage signal in an inductive bridge includes the following steps:

[0008] Step S1: Configure the detection unit and build the detection system;

[0009] Step S2: Glue the iron particles, copper particles, and aluminum particles to be tested onto the thin wire and fix them onto the lead screw and slide rail mechanism.

[0010] Step S3: Turn on the DC power supply; use a waveform generator to provide an excitation signal for the inductor bridge circuit and balance the bridge.

[0011] Step S4: Pass the metal particle to be detected through the detection oil channel and place it in the inductor coil L x At the center position, the control screw drives the metal particles at a constant speed within the inductor coil L. x The device performs reciprocating motion inside, while the data acquisition card collects voltage signal data and displays it on the computer.

[0012] Step S5: Change the running speed of the lead screw in the lead screw guide mechanism, and repeat step S4;

[0013] Step S6: Compare and analyze the voltage signal graphs of iron particles, copper particles, and aluminum particles at different velocities.

[0014] Further, in step S1, the detection unit includes: an oil passage through which the oil to be detected flows, and a spiral inductor L arranged in a circumferential manner on the inner wall of the oil passage. x In the inductor coil L x Solenoid reference coil L with leads connected at both ends n and potentiometer R a In the reference coil L n and potentiometer R a The resistor R connected to the other end of the lead b The inductor coil L x With reference coil L nThe lead wire is connected with the primary detection circuit module; the primary detection circuit module is connected with the terminal filter; the primary detection circuit module comprises a rectifier, a low-pass filter and a differential amplifier; the rectifier is connected with the low-pass filter; the low-pass filter is connected with the differential amplifier; the inductor coil L x , the reference coil L n , the potentiometer R a , the resistance R b , the primary detection circuit module and the terminal filter constitute an inductive bridge circuit.

[0015] Further, in the step S1, the inductive bridge circuit is connected with a direct current power supply; the inductive bridge circuit is connected with a waveform generator; the inductive bridge circuit is connected with a data acquisition card; and the data acquisition card is connected with a computer.

[0016] Further, in the step S4, the particles to be detected are driven to pass through the solenoid inductor coil L x at different speeds by a screw slide rail mechanism.

[0017] The solenoid inductor coil L x The angle difference between the magnetic induction lines at the entrance and exit and the magnetic induction lines inside the solenoid coil, when the particles pass through the place, cut the magnetic induction lines, generate a dynamic electromotive force, and the influence trend of the dynamic electromotive force can be observed in the voltage signal diagram, so as to analyze the relationship between the amplitude change amount of the voltage signal and the speed increase amount.

[0018] Compared with the prior art, the present application has the following advantages:

[0019] The inductive bridge method is applied to oil pollution detection to analyze the influence of the metal particle speed on the voltage signal.

[0020] The present application establishes a relationship model between the metal particle speed and the inductance change amount, and a relationship model between the metal particle speed and the output voltage of the bridge.

[0021] The present application solves the problem of the influence mechanism of the metal particle speed on the voltage signal to a certain extent. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0023] Figure 1 The flow chart is used for the implementation of the present application.

[0024] Figure 2 For the detection system device of the present application;

[0025] Figure 3 For the inductance bridge circuit diagram of the present application;

[0026] Figure 4 The voltage signal diagram affected by the electrokinetic electromotive force generated by iron, copper and aluminum particles;

[0027] Figure 5 For the voltage signal diagram collected when iron particles pass through the inductance coil at different speeds;

[0028] Figure 6 For the voltage signal diagram collected when copper particles pass through the inductance coil at different speeds;

[0029] Figure 7 For the voltage signal diagram collected when aluminum particles pass through the inductance coil at different speeds.

[0030] In the figure: 1, waveform generator; 2, DC power supply; 3, screw slide rail mechanism; 4, acquisition card; 5, computer; 6, inductance bridge; 7, primary detection circuit module; 8, terminal filter; 9, inductance coil L x ; 10, reference coil L n ; 11, potentiometer R a ; 12, resistance R b ; 13, rectifier; 14, low-pass filter; 15, differential amplifier. DETAILED DESCRIPTION

[0031] In order for those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the present application.

[0032] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0033] like Figures 1-7 As shown, this invention provides a method for analyzing the influence of metal particle velocity on the voltage signal in an inductor bridge. The steps of this method are described in detail below with reference to the accompanying drawings:

[0034] Step S1: Configure the detection unit and build the detection system;

[0035] Specifically, the detection unit includes an oil passage through which the oil to be detected flows, and a spiral inductor L arranged in a circumferential pattern on the inner wall of the oil passage. x In the inductor coil L x The two ends of the lead wire are respectively connected to a solenoid reference coil L. n and potentiometer R a In the reference coil L n and potentiometer R a The resistor R connected to the other end of the lead b The inductor coil L x With reference coil L n The lead wire is connected to the primary detection circuit module; the primary detection circuit module is connected to the terminal filter; the primary detection circuit module includes a rectifier, a low-pass filter, and a differential amplifier; the rectifier is connected to the low-pass filter; the low-pass filter is connected to the differential amplifier; the inductor L... x Reference coil L n Potentiometer R a Resistance R b The primary detection circuit module and the terminal filter constitute an inductor bridge circuit.

[0036] Setting up the detection system: The inductor bridge circuit is connected to a DC power supply; the inductor bridge circuit is connected to a waveform generator; the inductor bridge circuit is connected to a data acquisition card; the data acquisition card is connected to a computer.

[0037] S2: the to be detected iron particles, copper particles, aluminum particles are respectively adhered to the fine wire with glue and fixed on the screw slide rail mechanism;

[0038] S3: the direct current power supply is connected to supply power, the supply voltage is set to ±15V; the waveform generator is opened to provide an excitation signal for the inductive bridge circuit, the excitation signal is a sine wave signal, the excitation voltage is set to 10V, and the excitation frequency is set to 1.3MHZ; the inductive coil L x composes the first bridge arm in the bridge circuit, and the inductive coil L x is the to-be-detected inductance of the bridge arm; the potentiometer R a composes the second bridge arm in the bridge circuit; the reference coil L n composes the third bridge arm in the bridge circuit, and the resistor R b composes the fourth bridge arm in the bridge circuit; the alternating current power supply is connected at the connection point A of the first and third bridge arms and the connection point C of the second and fourth bridge arms; the connection point B of the first and second bridge arms and the connection point D of the third and fourth bridge arms serve as the output, and the output voltage is U BD , and the analysis circuit structure can obtain:

[0039]

[0040] wherein U i is the power supply voltage value, ω is the angular frequency of the alternating excitation, R x is the inductance coil resistance, and R n is the reference coil resistance. It can be known from the formula that the output voltage of the inductive bridge circuit can be zero by adjusting the resistance value of the potentiometer R a , and the inductive bridge reaches balance at this time.

[0041] S4: the to-be-detected metal particles are placed at the center position of the inductive coil L x , and the screw slide rail mechanism is controlled to drive the metal particles to reciprocate in the inductive coil L x at a constant speed. In step 3), when the inductive coil L x is connected to the alternating excitation, an alternating magnetic field is excited in the coil, and when the metal particles pass through the inlet and outlet of the inductive coil L x , the angle difference exists between the magnetic induction lines at the inlet and outlet of the solenoid coil and the magnetic induction lines inside the solenoid, the particles cut the magnetic induction lines when passing through the place, and the motional electromotive force ε m is generated, and the formula is:

[0042]

[0043] ε = ε t + ε m ;

[0044] wherein dl is the length differential of the eddy current loop inside the metal particle, is the magnetic induction between the metal particle and the inductive coil, is the movement speed of the metal particle in the magnetic field, ε is the induced electromotive force generated by the particle passing through the coil, ε t is the induced electromotive force changed by the change of the magnetic field. And from the definition of inductance, the change of inductance ΔL is:

[0045]

[0046] From the formula, the inductive coil L x induced electromotive force increases with the increase of the speed vector module of the metal particle passing through the magnetic field. That is, the greater the speed, the greater the induced electromotive force containing the dynamic electromotive force, and the greater the change of inductance caused by it. The inductive coil L x itself impedance value ΔL changes, breaks the original balance state of the bridge circuit, so that the output voltage U BD changes. The output voltage U BD The primary detection circuit module generates a voltage signal after rectification, denoising and amplification, and then the terminal filter filters to generate the final differential voltage. The differential voltage signal data is collected by the acquisition card and displayed on the computer side;

[0047] S5: Change the running speed of the lead screw slide rail mechanism, and repeat step S4;

[0048] S6: Compare and analyze the voltage signal graphs generated by the metal particles moving at different speeds obtained in the above steps.

[0049] In the above step S4, when the metal particle is stationary at the center axis of the inductive coil L x The change of inductance is:

[0050]

[0051] wherein Δz max is the impedance output by the coil detecting the particle, ω is the angular frequency of the alternating excitation, μ0 is the vacuum permeability, N is the number of turns of the inductive coil, w is the axial length of the inductive coil, d is the inner diameter of the inductive coil, k p is the magnetic factor of the metal particle. And the magnetic factor of the ferromagnetic metal particle is:

[0052]

[0053] The magnetic factor of the non-ferromagnetic metal particle is:

[0054]

[0055] wherein r is the radius of the particle, μ r is the relative permeability of the particle, the present patent assumes that the relative permeability of the particle is a real number and is not affected by frequency. σ is the conductivity. When the inductive coil L x is connected with AC excitation, an alternating magnetic field is generated inside the coil. Since the relative permeability of the ferromagnetic metal particle is much greater than 1, when the ferromagnetic metal particle passes through the inductive coil L x , it is magnetized, and the increased magnetic flux in the coil is much greater than the magnetic flux generated in the particle in the opposite direction of the magnetic flux to hinder the increase of the magnetic flux, so the change in the inductance of the coil caused by the ferromagnetic metal particle is positive.

[0056] Since the relative permeability of the non-ferromagnetic metal particle is slightly less than 1, when the particle enters the inductive coil L x , an electric current is generated inside the particle which can generate a magnetic flux in the opposite direction of the original magnetic flux, and when the excitation connected to the coil is high-frequency AC excitation, the magnetic flux of the original magnetic induction intensity is increased, so the change in the inductance of the coil caused by the ferromagnetic metal particle is negative.

[0057] The above-mentioned embodiment numbers of the present application are only for description, not representing the advantages and disadvantages of the embodiments.

[0058] In the above-mentioned embodiments of the present application, the description of each embodiment has its own emphasis, and the parts not described in detail in a certain embodiment can be referred to the related description of other embodiments.

[0059] Finally, it should be pointed out that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the above-mentioned embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the above-mentioned embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method of analyzing the effect of metal particle velocity on a voltage signal in an inductive bridge, characterized by, It comprises the following steps: S1: configure detection unit and build detection system; S2: the iron particles, copper particles, aluminum particles to be detected are respectively adhered to the fine wire with glue and fixed on the screw slide rail mechanism; S3: Connect the DC power supply; use a waveform generator to provide an excitation signal to the inductor bridge circuit and balance the bridge; turn on the waveform generator to provide an excitation signal to the inductor bridge circuit. The excitation signal is a sine wave signal, the excitation voltage is set to 10V, and the excitation frequency is set to 1.3MHz; inductor coil The inductor coil forms the first arm of the bridge circuit. The inductance to be measured in this bridge arm; potentiometer The second arm of the bridge circuit; reference coil The resistor forms the third arm of the bridge circuit. It forms the fourth arm of the bridge circuit; AC power is connected at the connection point A of the first and third arms and the connection point C of the second and fourth arms; the connection point B of the first and second arms and the connection point D of the third and fourth arms serve as the output, and its output voltage is... Analysis of the circuit structure reveals the following: ； wherein, is the AC supply voltage value, is the angular frequency of the AC supply, is the inductance coil internal resistance, is the reference coil internal resistance; from the formula, by adjusting the potentiometer resistance value can make the inductance bridge circuit output voltage to zero, at this time the inductance bridge reaches equilibrium; S4: the metal particles to be detected are placed in the inductor coil through the detection oil channel At the center position, the control screw drives the metal particles to reciprocate in the inductor coil at a constant speed, while the data acquisition card collects voltage signal data and displays it on the computer; the inductor coil When connected to an AC power source, it generates an alternating magnetic field inside the coil. When the metal particles pass through the inductor coil At the entrance and exit, due to the angle difference between the magnetic induction lines at the entrance and exit of the solenoid coil and the magnetic induction lines inside the solenoid, the particles cut the magnetic induction lines when passing through this place, generating a motional electromotive force The formula is: ； ； wherein, is the length differential of the eddy current loop inside the metal particle, is the magnetic induction between the metal particle and the inductive coil, is the velocity of the metal particle in the magnetic field, is the induced electromotive force generated by the particle passing through the coil, is the induced electromotive force changed by the change of the magnetic field; and the change amount of the inductance is: ； As can be seen from the formula, the inductance caused by metal particles is... The induced electromotive force increases with the velocity vector magnitude of the metal particles passing through the magnetic field; that is, the greater the velocity, the greater the induced electromotive force, including the motional electromotive force, and the greater the change in inductance it causes; the inductor coil Self-impedance value The change disrupts the original balance of the bridge circuit, causing the bridge output voltage to... Changes occur; output voltage The primary detection circuit module generates a voltage signal that has been rectified, denoised, and amplified. This signal is then filtered by a terminal filter to produce the final differential voltage. The acquisition card collects this differential voltage signal data and displays it on a computer. When the metal particles are stationary in the inductor coil... The change in inductance at the central axis is: ； wherein, is the impedance output by the coil for detecting the particles, is the angular frequency of the alternating current power supply, is the vacuum permeability, is the number of turns of the inductive coil, is the axial length of the inductive coil, is the inner diameter of the inductive coil, is the magnetization factor of the metal particles; and the magnetization factor of the ferromagnetic metal particles is: ； The magnetization factor of the non-ferromagnetic metal particles is: ； wherein, is the radius of the particle, is the relative permeability of the particle, assuming the relative permeability of the particle is a real number and is not affected by frequency; , is the electrical conductivity; when the inductive coil is connected to an alternating current source, an alternating magnetic field is generated inside the coil; because the relative permeability of the ferromagnetic metal particles is much greater than 1, when the ferromagnetic metal particles pass through the inductive coil they are magnetized, and the increased magnetic flux in the coil is much greater than the magnetic flux generated by the ferromagnetic metal particles in the opposite direction to the magnetic flux generated by the coil, so the change in inductance of the coil caused by the ferromagnetic metal particles is positive; Since the relative permeability of the non-ferromagnetic metal particles is slightly less than 1, when the particles enter the inductor coil , the current in the particles is generated in the opposite direction of the magnetic induction lines of the original magnetic field, and when the excitation of the coil is a high-frequency alternating current source, the magnetic flux of the original magnetic induction intensity that is offset increases, so the inductance change caused by the ferromagnetic metal particles is negative. S5: change the running speed of the screw in the screw slide rail mechanism, and repeat step S4; S6: compare and analyze the voltage signal graphs of the iron particles, copper particles and aluminum particles at different speeds.

2. The method of claim 1, wherein the step S1 comprises: connecting the inductance bridge circuit with a direct current power supply; connecting the inductance bridge circuit with a waveform generator; connecting the inductance bridge circuit with a data acquisition card; and connecting the data acquisition card with a computer. The detection unit in step S1 comprises an oil passage through which the oil liquid to be detected flows, and a solenoid inductor coil arranged around the inner wall of the oil passage , the inductor coil , the reference coil , the potentiometer , the reference coil , the potentiometer , the resistor ; the inductor coil , the reference coil , the lead wire is connected to the primary detection circuit module; the primary detection circuit module is connected to the terminal filter; the primary detection circuit module comprises a rectifier, a low-pass filter and a differential amplifier; the rectifier is connected to the low-pass filter; the low-pass filter is connected to the differential amplifier; the inductor coil , the reference coil , the potentiometer , the resistor , the primary detection circuit module and the terminal filter constitute an inductor bridge circuit.

3. The method of claim 1, wherein the step S1 comprises: connecting the inductance bridge circuit with a direct current power supply; connecting the inductance bridge circuit with a waveform generator; connecting the inductance bridge circuit with a data acquisition card; and connecting the data acquisition card with a computer.

4. The method of claim 1, wherein the step S1 comprises: connecting the inductance bridge circuit with a direct current power supply; connecting the inductance bridge circuit with a waveform generator; connecting the inductance bridge circuit with a data acquisition card; and connecting the data acquisition card with a computer. ​ In the step S4, the particles to be detected are driven through the solenoid inductance coil at different speeds by a screw slide rail mechanism ; The solenoid inductor The angle difference between the magnetic induction lines at the entrance and exit and the magnetic induction lines inside the solenoid, the particles cut the magnetic induction lines when passing through the place, generate the dynamic electromotive force, and the influence trend of the dynamic electromotive force can be observed in the voltage signal diagram, so as to analyze the relationship between the amplitude change amount of the voltage signal and the speed increase amount.

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