Induction type oil abrasive dust sensor module value phase-sensitive detection demodulation system and method

Abstract

The invention provides a module value phase-sensitive detection demodulation system and method for an induction type oil abrasive dust sensor, and belongs to the technical field of induction type oil abrasive dust sensors, and the system comprises a pre-amplification circuit which is used for amplifying an induction signal to obtain an amplification signal; the module value processing circuit is used for performing module value processing on the amplified signal to obtain a module value signal; the signal demodulation circuit is used for performing phase-sensitive detection demodulation on the module value signal to obtain a demodulation signal; and the low-pass filter circuit is used for filtering the demodulation signal to obtain a metal particle signal. The device can be applied to a sensor signal processing part for online monitoring of oil abrasive particles, the circuit is simple, the operation speed is high, application is convenient, output voltage with larger amplitude can be obtained, the cost can be reduced, and the working speed of a system can be increased.

Description

Technical Field

[0001] The invention relates to the technical field of inductive oil wear debris sensors, and in particular to a module value phase-sensitive detection demodulation system and method for an inductive oil wear debris sensor. Background Art

[0002] In modern industrial and mechanical equipment, wear debris monitoring in lubricating oil is a key health monitoring technology. By detecting and analyzing metal wear debris in oil, wear, corrosion and failure signs of mechanical parts can be discovered in time, so as to perform preventive maintenance and avoid sudden equipment failures and economic losses. In the fields of aerospace, automobile manufacturing, power generation equipment, etc., oil wear debris monitoring has been widely used and is an important means to ensure the safe and stable operation of equipment.

[0003] Traditional oil wear debris monitoring methods, such as optical detection and ultrasonic detection, have certain limitations, such as the inability to detect in real time, low sensitivity or high cost. In contrast, inductive oil wear debris sensors have the advantages of non-contact measurement, real-time online monitoring and high sensitivity, and have gradually become an effective monitoring method. However, since the signals detected by the sensor are usually weak and easily interfered by environmental noise, how to effectively extract and process these weak signals has become a key challenge to improve the accuracy and reliability of the monitoring system. Summary of the invention

[0004] The present invention provides an analog phase-sensitive detection demodulation system and method for an inductive oil wear debris sensor, the purpose of which is to distinguish the phase of the modulation signal through a phase-sensitive detection circuit, and then judge the phase change of the measured value, so as to distinguish the properties of the metal particles. At the same time, the phase-sensitive detection circuit also has the ability to select frequencies, which improves the anti-interference ability of the sensor circuit. Compared with the traditional analog multiplier phase-sensitive detector, the analog phase-sensitive detection demodulation has a large dynamic range and strong overload resistance, simplifies the circuit design, improves the stability of the signal conditioning circuit, and is conducive to reducing costs and improving the working speed of the system.

[0005] This specification discloses an inductive oil wear chip sensor modulus phase-sensitive detection demodulation system, comprising:

[0006] A preamplifier circuit is used to amplify the sensing signal to obtain an amplified signal;

[0007] A modulus processing circuit, used for performing modulus processing on the amplified signal to obtain a modulus signal;

[0008] A signal demodulation circuit is used to perform phase-sensitive detection demodulation on the modulus signal to obtain a demodulated signal;

[0009] A low-pass filter circuit, used for filtering the demodulated signal to obtain a metal particle signal;

[0010] The first-stage amplifier circuit of the preamplifier circuit amplifies the sensing signal by 510 times through the amplifier chip U1 to obtain the first-stage amplified signal. The amplification factor is adjustable, and the calculation formula is:

[0011]

[0012] G1 is the gain of the first-stage amplifier circuit, R2 is the feedback resistor of the first-stage amplifier circuit, and R1 is the grounding resistor of the first-stage amplifier circuit;

[0013] The second stage amplification circuit of the preamplification circuit amplifies the first stage amplification signal by 100 times through the amplification chip U2 to obtain the second stage amplification signal. The amplification factor is adjustable, and the calculation formula is:

[0014]

[0015] G2 is the gain of the second-stage amplifier circuit, R4 is the feedback resistor of the second-stage amplifier circuit, and R3 is the grounding resistor of the second-stage amplifier circuit;

[0016] The preamplifier circuit includes an amplifier chip U1, an amplifier chip U2, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, and a capacitor C7;

[0017] One end of the capacitor C5 is connected to one end of the capacitor C3 and then receives the induction signal. The other end of the capacitor C5 is grounded. The other end of the capacitor C3 is connected to the pin 3 of the amplifier chip U1 and the grounded resistor R6. The pin 4 of the amplifier chip U1 is connected to the grounded capacitor C6 and then connected to an external -15V power supply. The pin 2 of the amplifier chip U1 is connected to one end of the resistor R2 and the grounded resistor R1. The other end of the resistor R2 is connected to the pin 6 of the amplifier chip U1 as the first stage amplified signal output end. The pin 7 of the amplifier chip U1 is connected to the grounded capacitor C1 and then connected to an external +15V power supply. One end of the resistor R5 is connected to pin 6 of the amplifier chip U1, the other end of the resistor R5 is connected to the capacitor C4, the other end of the capacitor C4 is connected to pin 3 of the amplifier chip U2 and a grounded resistor R7, pin 4 of the amplifier chip U2 is connected to the grounded capacitor C7 and then connected to an external -15V power supply, pin 2 of the amplifier chip U2 is connected to one end of the resistor R4 and the grounded resistor R3, the other end of the resistor R4 is connected to pin 6 of the amplifier chip U2 as a second-stage amplified signal output end, and pin 7 of the amplifier chip U2 is connected to the grounded capacitor C2 and then connected to an external +15V power supply.

[0018] In this specification, the modulus processing circuit includes an operational amplifier U3, an operational amplifier U4, a resistor R11, a resistor R8, a resistor R9, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a diode D3, and a diode D4; one end of the resistor R11 is connected to the second-stage amplified signal, the other end of the resistor R11 is connected to pin 2 of the operational amplifier U3, one end of the resistor R8 is connected to pin 2 of the operational amplifier U3, the other end of the resistor R8 is connected to the positive electrode of the diode D3 and one end of the resistor R9, the other end of the resistor R9 is connected to pin 2 of the operational amplifier U4 and one end of the resistor R10, and the other end of the resistor R10 is connected to Pin 6 of the operational amplifier U4 is connected to one end of the resistor R12, one end of the resistor R13 is connected to pin 2 of the operational amplifier U3, the other end of the resistor R13 is connected to the cathode of the diode D4 and pin 3 of the operational amplifier U4, the cathode of the diode D3 is connected to the anode of the diode D4 and pin 6 of the operational amplifier U3, pin 3 of the operational amplifier U3 is grounded, pin 4 of the operational amplifier U3 is connected to an external -15V power supply, pin 7 of the operational amplifier U3 is connected to an external +15V power supply, pin 4 of the operational amplifier U4 is connected to an external -15V power supply, pin 7 of the operational amplifier U4 is connected to an external +15V power supply, and pin 6 of the operational amplifier U4 outputs a modulus signal.

[0019] In this specification, the modulus processing circuit receives the second-stage amplified signal. When the input signal is in the positive half cycle, the diode D3 is turned on, the diode D4 is turned off, and the reverse input terminal of the operational amplifier U3 is 0. Due to the virtual disconnection, no current flows into the same-direction input terminal of the operational amplifier U4, so the current can only take the AB path, and Vout = Vin at this time; when the input signal is in the negative half cycle, the diode D3 is turned off, the diode D4 is turned on, and the reverse input terminal of the operational amplifier U3 is 0. At this time, there are two main paths for the current flowing from the reverse input terminal to the signal terminal. The first path is from point B through resistor R9 and then through resistor R8 to pin 2 of the operational amplifier U3. The second path is output from pin 6 of the operational amplifier U3 through resistor R13 to pin 2 of the operational amplifier U3. Due to the virtual short, the potential of point B and pin 3 of the operational amplifier U4 are equal. At this time, the voltage at point B can be obtained according to Kirchhoff's current law. Since resistors R8, R9, R10 and the operational amplifier U4 form a same-direction amplifier with a gain of 3 / 2, Vout = Vin; wherein: Vi n is the signal input of the analog value processing circuit; Vout is the signal output of the analog value processing circuit.

[0020] In this specification, the signal demodulation circuit performs phase-sensitive detection demodulation on the signal after the modulus processing to obtain a demodulated signal; according to the analog multiplier type phase-sensitive detection demodulation method, the output u of the analog multiplier type phase-sensitive detector is obtained. p (t), is the product of the measured modulation signal x(t) and the reference signal r(t) of the two input signals, that is: up (t) = x(t)r(t);

[0021] Both x(t) and r(t) are sine waves. Assume that the modulated signal to be measured is: x(t) = V s cos(ω0t+θ);

[0022] The reference signal is: r(t) = V r cos(ω0t);

[0023] Where ω0 is the frequency of the measured modulated signal and the reference signal, and θ is the phase difference between the measured modulated signal and the reference signal;

[0024] After calculation and simplification, we can get:

[0025] u p (t) = x(t)r(t) = V s cos(ω0t+θ)V r cos(ω0t)=0.5V s V r cosθ+0.5V s V r cos(2ω0t+θ);

[0026] The output signal after filtering is:

[0027] u0(t)=0.5V s V r cosθ;

[0028] Modulus phase-sensitive detection is equivalent to adjusting the reference signal to:

[0029]

[0030] Among them, a0 is the DC component after being expanded into Fourier series, a m is the Fourier coefficient of the cosine component, b m is the Fourier coefficient of the sinusoidal component, ω0 is the angular frequency;

[0031] After calculation and simplification, the output signal is:

[0032]

[0033] Where: u0(t) is the output voltage signal, V s is the amplitude of the modulated signal being measured, V r is the amplitude of the reference signal.

[0034] In this specification, the signal demodulation circuit includes a chip U5, a resistor R12, a capacitor C9, and a capacitor C14; one end of the resistor R12 is connected to the analog signal, and the other end of the resistor R12 is connected to pin 1, pin 10, and pin 16 of the chip U5, pin 8 of the chip U5 is connected to the grounded capacitor C9 and then connected to an external -15V power supply, pin 9 of the chip U5 is grounded, pin 11 of the chip U5 is connected to the grounded capacitor C14 and then connected to an external +15V power supply, pin 14 and pin 17 of the chip U5 are grounded, and pin 15, pin 19, and pin 20 of the chip U5 are connected.

[0035] In this specification, the low-pass filter circuit uses a fourth-order low-pass filter to filter the demodulated signal to obtain a metal particle signal. The low-pass frequency is adjustable, and the calculation formula is:

[0036]

[0037] Where: f0 is the cut-off frequency, R is the resistance value, and C is the capacitance value.

[0038] In this specification, the low-pass filter circuit includes a chip U6, a resistor R14, a resistor R15, a resistor R16, a resistor R20, a resistor R25, a capacitor C8, a capacitor C10, a capacitor C11, a capacitor C12, a capacitor C13, a capacitor C15, and a capacitor C16; one end of the resistor R14 is connected to the chip end signal, the other end of the resistor R14 is connected to one end of the capacitor C10 and one end of the resistor R15, the other end of the capacitor C10 is connected to pin 1 of the chip U6, the other end of the resistor R15 is connected to the grounded capacitor C12 and the pin 3 of the chip U6, the pin 4 of the chip U6 is connected to the grounded capacitor C13 and then externally connected to - 15V power supply, one end of the resistor R20 is connected to pin 1 and pin 2 of the chip U6, the other end of the resistor R20 is connected to one end of the capacitor C11 and one end of the resistor R16, the other end of the capacitor C11 is connected to pin 7 of the chip U6 and one end of the capacitor C16, the other end of the resistor R16 is connected to the grounded capacitor C15 and pin 5 of the chip U6, pin 1 and pin 2 of the chip U6 are connected, pin 6 and pin 7 of the chip U6 are connected, pin 8 of the chip U6 is connected to the grounded capacitor C8 and then connected to an external +15V power supply, and the other end of the capacitor C16 is connected to the grounded resistor R25.

[0039] This specification also discloses a method for modulus phase-sensitive detection and demodulation of an inductive oil wear chip sensor, which is implemented by any one of the above-mentioned modulus phase-sensitive detection and demodulation systems of the inductive oil wear chip sensor. The method comprises:

[0040] S1. Amplify the sensing signal through the preamplifier circuit to obtain an amplified signal;

[0041] S2. Performing modulus processing on the amplified signal through a modulus processing circuit to obtain a modulus signal;

[0042] S3. Perform phase-sensitive detection demodulation on the modulus signal through a signal demodulation circuit to obtain a demodulated signal;

[0043] S4. Filter the demodulated signal through a low-pass filter circuit to obtain a metal particle signal.

[0044] The embodiments of this specification can at least achieve the following beneficial effects:

[0045] The phase-sensitive detection circuit of the present invention can distinguish the phase of the modulated signal and has the ability of frequency selection, thereby improving the anti-interference ability of the sensor circuit, having a large demodulation dynamic range, strong anti-overload ability, a simple circuit structure, and strong stability of the signal conditioning circuit, which is conducive to reducing costs and improving the working speed of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0047] Figure 1 It is a schematic diagram of the modulus phase-sensitive detection and demodulation system of the inductive oil wear debris sensor involved in the present invention.

[0048] Figure 2 It is a schematic diagram of the preamplifier circuit involved in the present invention.

[0049] Figure 3 It is a schematic diagram of the modulus processing circuit involved in the present invention.

[0050] Figure 4 It is a schematic diagram of a signal demodulation circuit involved in the present invention.

[0051] Figure 5 It is a schematic diagram of the low-pass filter circuit involved in the present invention.

[0052] Figure 6 It is a schematic diagram comparing the original signal waveform and the modulus signal waveform involved in the present invention.

[0053] Figure 7 It is a schematic diagram comparing the output signals of the analog multiplier phase-sensitive detection and the analog value processing phase-sensitive detection involved in the present invention. DETAILED DESCRIPTION

[0054] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the embodiments of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0055] The disclosure below provides many different embodiments or examples to implement different structures of the embodiments of the present invention. In order to simplify the disclosure of the embodiments of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the embodiments of the present invention. In addition, the embodiments of the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed.

[0056] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0057] like Figure 1 As shown, the embodiment of this specification provides an inductive oil wear chip sensor modulus phase-sensitive detection demodulation system, including:

[0058] The preamplifier circuit is used to amplify the sensing signal (the output signal of the inductive oil wear debris sensor) to obtain an amplified signal;

[0059] A modulus processing circuit, used for performing modulus processing on the amplified signal to obtain a modulus signal;

[0060] A signal demodulation circuit is used to perform phase-sensitive detection demodulation on the modulus signal to obtain a demodulated signal;

[0061] A low-pass filter circuit, used for filtering the demodulated signal to obtain a metal particle signal;

[0062] The first-stage amplifier circuit of the preamplifier circuit amplifies the sensing signal by 510 times through the amplifier chip U1 to obtain the first-stage amplified signal. The amplification factor is adjustable, and the calculation formula is:

[0063]

[0064] G1 is the gain of the first-stage amplifier circuit, R2 is the feedback resistor of the first-stage amplifier circuit, and R1 is the grounding resistor of the first-stage amplifier circuit;

[0065] The second stage amplification circuit of the preamplification circuit amplifies the first stage amplification signal by 100 times through the amplification chip U2 to obtain the second stage amplification signal. The amplification factor is adjustable, and the calculation formula is:

[0066]

[0067] G2 is the gain of the second-stage amplifier circuit, R4 is the feedback resistor of the second-stage amplifier circuit, and R3 is the grounding resistor of the second-stage amplifier circuit;

[0068] like Figure 2 As shown, the preamplifier circuit includes an amplifier chip U1, an amplifier chip U2, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, and a capacitor C7;

[0069] One end of the capacitor C5 is connected to one end of the capacitor C3 and then receives the induction signal. The other end of the capacitor C5 is grounded. The other end of the capacitor C3 is connected to the pin 3 of the amplifier chip U1 and the grounded resistor R6. The pin 4 of the amplifier chip U1 is connected to the grounded capacitor C6 and then connected to an external -15V power supply. The pin 2 of the amplifier chip U1 is connected to one end of the resistor R2 and the grounded resistor R1. The other end of the resistor R2 is connected to the pin 6 of the amplifier chip U1 as the first stage amplified signal output end. The pin 7 of the amplifier chip U1 is connected to the grounded capacitor C1 and then connected to an external +15V power supply. One end of the resistor R5 is connected to pin 6 of the amplifier chip U1, the other end of the resistor R5 is connected to the capacitor C4, the other end of the capacitor C4 is connected to pin 3 of the amplifier chip U2 and a grounded resistor R7, pin 4 of the amplifier chip U2 is connected to the grounded capacitor C7 and then connected to an external -15V power supply, pin 2 of the amplifier chip U2 is connected to one end of the resistor R4 and the grounded resistor R3, the other end of the resistor R4 is connected to pin 6 of the amplifier chip U2 as a second-stage amplified signal output end, and pin 7 of the amplifier chip U2 is connected to the grounded capacitor C2 and then connected to an external +15V power supply.

[0070] In some embodiments, Figure 3As shown, the modulus processing circuit includes an operational amplifier U3, an operational amplifier U4, a resistor R11, a resistor R8, a resistor R9, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a diode D3, and a diode D4; one end of the resistor R11 is connected to the second-stage amplified signal, the other end of the resistor R11 is connected to pin 2 of the operational amplifier U3, one end of the resistor R8 is connected to pin 2 of the operational amplifier U3, the other end of the resistor R8 is connected to the positive electrode of the diode D3 and one end of the resistor R9, the other end of the resistor R9 is connected to pin 2 of the operational amplifier U4 and one end of the resistor R10, and the other end of the resistor R10 is connected to the Pin 6 of the operational amplifier U4 is connected to one end of the resistor R12, one end of the resistor R13 is connected to pin 2 of the operational amplifier U3, the other end of the resistor R13 is connected to the cathode of the diode D4 and the pin 3 of the operational amplifier U4, the cathode of the diode D3 is connected to the anode of the diode D4 and the pin 6 of the operational amplifier U3, the pin 3 of the operational amplifier U3 is grounded, the pin 4 of the operational amplifier U3 is externally connected to a -15V power supply, the pin 7 of the operational amplifier U3 is externally connected to a +15V power supply, the pin 4 of the operational amplifier U4 is externally connected to a -15V power supply, the pin 7 of the operational amplifier U4 is externally connected to a +15V power supply, and the pin 6 of the operational amplifier U4 outputs a modulus signal.

[0071] In some embodiments, the modulus processing circuit receives the second-stage amplified signal. When the input signal is in the positive half cycle, the diode D3 is turned on, the diode D4 is turned off, and the reverse input terminal of the operational amplifier U3 is 0. Due to the virtual disconnection, no current flows into the same-direction input terminal of the operational amplifier U4, so the current can only take the AB path, and Vout=Vi n at this time; when the input signal is in the negative half cycle, the diode D3 is turned off, the diode D4 is turned on, and the reverse input terminal of the operational amplifier U3 is 0. At this time, there are two main paths for the current flowing from the reverse input terminal to the signal terminal. The first path is from point B through R9 and then through R8 to pin 2 of U3. The second path is output from pin 6 of U3 through R13 to pin 2 of U3. Due to the virtual short, the potential of point B and pin 3 of U4 are equal. At this time, the voltage at point B can be obtained according to Kirchhoff's current law. Since resistors R8, R9, R10 and the operational amplifier U4 form a same-direction amplifier with a gain of 3 / 2, Vout=Vi n; wherein: Vi n is the signal input of the analog value processing circuit; Vout is the signal output of the analog value processing circuit.

[0072] In some embodiments, the signal demodulation circuit performs phase-sensitive detection demodulation on the signal after the modulus processing to obtain a demodulated signal; according to the analog multiplier type phase-sensitive detection demodulation method, the output u of the analog multiplier type phase-sensitive detector is obtained. p (t), is the product of the two input signals, the measured modulation signal x(t) and the reference signal r(t), that is: p (t) = x(t)r(t);

[0073] Both x(t) and r(t) are sine waves. Assume that the modulated signal to be measured is: x(t) = V s cos(ω0t+θ);

[0074] The reference signal is: r(t) = V r cos(ω0t);

[0075] Where ω0 is the frequency of the measured modulated signal and the reference signal, and θ is the phase difference between the measured modulated signal and the reference signal;

[0076] After calculation and simplification, we can get:

[0077] u p (t) = x(t)r(t) = V s cos(ω0t+θ)V r cos(ω0t)=0.5V s V r cosθ+0.5V s V r cos(2ω0t+θ);

[0078] The output signal after filtering is:

[0079] u0(t)=0.5V s V r cosθ;

[0080] Modulus phase-sensitive detection is equivalent to adjusting the reference signal to:

[0081]

[0082] Among them, a0 is the DC component after being expanded into Fourier series, a m is the Fourier coefficient of the cosine component, b m is the Fourier coefficient of the sinusoidal component, ω0 is the angular frequency;

[0083] After calculation and simplification, the output signal is:

[0084]

[0085] Where: u0(t) is the output voltage signal, V s is the amplitude of the modulated signal being measured, V r is the amplitude of the reference signal.

[0086] In some embodiments, Figure 4As shown, the signal demodulation circuit includes a chip U5, a resistor R12, a capacitor C9, and a capacitor C14; one end of the resistor R12 is connected to the analog value signal, and the other end of the resistor R12 is connected to pin 1, pin 10, and pin 16 of the chip U5, and pin 8 of the chip U5 is connected to the grounded capacitor C9 and then connected to an external -15V power supply, pin 9 of the chip U5 is grounded, and pin 11 of the chip U5 is connected to the grounded capacitor C14 and then connected to an external +15V power supply, pin 14 and pin 17 of the chip U5 are grounded, and pin 15, pin 19, and pin 20 of the chip U5 are connected.

[0087] In some embodiments, the low-pass filter circuit uses a fourth-order low-pass filter to filter the demodulated signal to obtain a metal particle signal. The low-pass frequency is adjustable, and the calculation formula is:

[0088]

[0089] Where: f0 is the cut-off frequency, R is the resistance value, and C is the capacitance value.

[0090] In some embodiments, Figure 5 As shown, the low-pass filter circuit includes a chip U6, a resistor R14, a resistor R15, a resistor R16, a resistor R20, a resistor R25, a capacitor C8, a capacitor C10, a capacitor C11, a capacitor C12, a capacitor C13, a capacitor C15, and a capacitor C16; one end of the resistor R14 is connected to the chip end signal, the other end of the resistor R14 is connected to one end of the capacitor C10 and one end of the resistor R15, the other end of the capacitor C10 is connected to pin 1 of the chip U6, the other end of the resistor R15 is connected to the grounded capacitor C12 and pin 3 of the chip U6, the pin 4 of the chip U6 is connected to the grounded capacitor C13 and then connected to an external -1 5V power supply, one end of the resistor R20 is connected to pin 1 and pin 2 of the chip U6, the other end of the resistor R20 is connected to one end of the capacitor C11 and one end of the resistor R16, the other end of the capacitor C11 is connected to pin 7 of the chip U6 and one end of the capacitor C16, the other end of the resistor R16 is connected to the grounded capacitor C15 and pin 5 of the chip U6, pin 1 and pin 2 of the chip U6 are connected, pin 6 and pin 7 of the chip U6 are connected, pin 8 of the chip U6 is connected to the grounded capacitor C8 and then connected to an external +15V power supply, and the other end of the capacitor C16 is connected to the grounded resistor R25.

[0091] The embodiment of the present specification also provides a method for modulus phase-sensitive detection and demodulation of an inductive oil wear chip sensor, which is implemented by any one of the above-mentioned modulus phase-sensitive detection and demodulation systems of the inductive oil wear chip sensor. The method for modulus phase-sensitive detection and demodulation of the inductive oil wear chip sensor includes:

[0092] S1. Amplify the sensing signal through the preamplifier circuit to obtain an amplified signal;

[0093] S2. Performing modulus processing on the amplified signal through a modulus processing circuit to obtain a modulus signal;

[0094] S3. Perform phase-sensitive detection demodulation on the modulus signal through a signal demodulation circuit to obtain a demodulated signal;

[0095] S4. Filter the demodulated signal through a low-pass filter circuit to obtain a metal particle signal.

[0096] The technical concept of the present invention is as follows:

[0097] like Figure 1 As shown, the present invention processes the sensor output signal so that the signal enters the preamplifier part, and amplifies the signal through the two-stage amplifier OPA627 and OP37 to enhance the amplitude and clarity of the signal; then, the signal after the modulus processing circuit is sent to the demodulation part, and AD630 is used for phase demodulation to extract the effective signal; the demodulated signal is filtered out of high-frequency noise through a low-pass filter to obtain a smooth signal output; finally, the processed signal is output from the output end to provide a stable signal output for subsequent analysis.

[0098] like Figure 3 As shown, the modulus processing circuit performs modulus processing on the input signal, which is similar to Figure 4 The signal demodulation circuit shown constitutes a modulus phase-sensitive detection circuit.

[0099] Analog phase-sensitive detection is a signal demodulation method based on and optimized analog multiplier phase-sensitive detection. It can improve the amplitude and stability of the output signal. p (t) is the product of its two input signals (the measured modulated signal x(t) and the reference signal r(t)), that is, u p (t) = x(t)r(t), x(t) and r(t) are both sine waves, and the measured modulation signal is x(t) = V s cos(ω0t+θ), the reference input is r(t)=V r cos(ω0t), where ω0 is the frequency of the measured modulated signal and the reference signal, and θ is the phase difference between them. After calculation simplification, we can get u p (t) = x(t)r(t) = Vs cos(ω0t+θ)V r cos(ω0t)=0.5V s V r cosθ+0.5V s V r cos(2ω0t+θ), the output signal after filtering is u0(t)=0.5V s V r cosθ. The modulus phase-sensitive detection is based on the change and optimization of the reference input signal. The reference input is After calculation and simplification, the output signal is: Therefore, the amplitude of the output signal of the modulus phase-sensitive detection is larger, and the structure is simpler and the stability is higher.

[0100] like Figure 6 As shown, after the pre-amplified signal is processed by analog value, the original signal waveform and the waveform after analog value processing are compared, and it can be obtained that the signals are all presented in the positive half cycle. Then the signal is input as a reference signal, and the next step of demodulation can be carried out.

[0101] like Figure 7 As shown in the figure, the amplitude of the output signal of the analog phase-sensitive detection is larger than that of the analog multiplier phase-sensitive detection, which is consistent with the result derived from the previous formula, which is approximately times.

[0102] In summary, the present invention provides a phase-sensitive demodulation system and method for an inductive oil wear debris sensor. The phase of the modulation signal is distinguished by a phase-sensitive detection circuit, and then the phase change of the measured value is determined, thereby distinguishing the properties of the metal particles. At the same time, the phase-sensitive detection circuit also has the ability to select frequencies, which improves the anti-interference ability of the sensor circuit. Figure 7 As shown, compared with the traditional analog multiplier phase-sensitive detector, the analog phase-sensitive detection demodulation has a large dynamic range and strong overload resistance, simplifies the circuit design, improves the stability of the signal conditioning circuit, and is conducive to reducing costs and increasing the operating speed of the system.

[0103] The above-described embodiments are used to illustrate the present invention, not to limit the present invention, so changes in the exemplified values ​​or replacement of equivalent elements should still fall within the scope of the present invention.

[0104] From the above detailed description, it can be understood by those skilled in the art that the present invention can indeed achieve the aforementioned objectives and is in compliance with the provisions of the Patent Law.

[0105] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic creative concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention. The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. It should be pointed out that any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

[0106] It should be noted that the above description of the relevant process is only for example and explanation, and does not limit the scope of application of this specification. For those skilled in the art, various modifications and changes can be made to the process under the guidance of this specification. However, these modifications and changes are still within the scope of this specification.

[0107] The basic concepts have been described above. Obviously, for those of ordinary skill in the art who have read this application, the above invention disclosure is only for example and does not constitute a limitation of this application. Although not explicitly stated here, those of ordinary skill in the art may make various modifications, improvements and amendments to this application. Such modifications, improvements and amendments are suggested in this application, so such modifications, improvements and amendments still belong to the spirit and scope of the exemplary embodiments of this application.

[0108] At the same time, the present application uses specific words to describe the embodiments of the present application. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.

[0109] In addition, it will be appreciated by those skilled in the art that various aspects of the present application may be illustrated and described by a number of patentable categories or situations, including any new and useful combination of processes, machines, products or substances, or any new and useful improvements thereto. Therefore, various aspects of the present application may be implemented entirely by hardware, entirely by software (including firmware, resident software, microcode, etc.), or by a combination of hardware and software. The above hardware or software may all be referred to as "units", "modules" or "systems". In addition, various aspects of the present application may take the form of a computer program product embodied in one or more computer-readable media, wherein computer-readable program code is contained therein.

[0110] The computer program code required for the operation of each part of the application can be written in any one or more programming languages, including object-oriented programming languages ​​such as Java, Scala, Smalltalk, Eiffel, JADE, Emerald, C++, C#, VB.NET, Python, etc., such as C programming language, VisualBasic, Fortran2103, Perl, COBOL2102, PHP, ABAP, such as Python, Ruby and Groovy dynamic programming language or other programming languages. The program code can be run completely on the user's computer, or run on the user's computer as an independent software package, or run partly on the user's computer and partly on the remote computer, or run completely on the remote computer or server. In the latter case, the remote computer can be connected to the user's computer through any network form, such as a local area network (LAN) or a wide area network (WAN), or connected to an external computer (e.g., via the Internet), or in a cloud computing environment, or used as a service such as software as a service (SaaS).

[0111] In addition, unless explicitly stated in the claims, the order of the processing elements and sequences described in this application, the use of alphanumeric characters, or the use of other names are not intended to limit the order of the processes and methods of this application. Although the above disclosure discusses some invention embodiments that are currently considered useful through various examples, it should be understood that such details are only for illustrative purposes, and the attached claims are not limited to the disclosed embodiments. On the contrary, the claims are intended to cover all modifications and equivalent combinations that are consistent with the essence and scope of the embodiments of this application. For example, although the implementation of the various components described above can be embodied in a hardware device, it can also be implemented as a pure software solution, for example, installation on an existing server or mobile device.

[0112] Similarly, it should be noted that in order to simplify the description disclosed in this application and thus help understand one or more embodiments of the invention, in the above description of the embodiments of the application, multiple features are sometimes combined into one embodiment, figure or description thereof. However, this method of the application should not be interpreted as reflecting the intention that the claimed object requires more features than those explicitly stated in each claim. On the contrary, the subject of the invention should have fewer features than the above single embodiment.

Claims

1. An inductive oil wear debris sensor modulus phase-sensitive detection demodulation system, characterized in that: include: A preamplifier circuit is used to amplify the sensing signal to obtain an amplified signal; A modulus processing circuit, used for performing modulus processing on the amplified signal to obtain a modulus signal; A signal demodulation circuit is used to perform phase-sensitive detection demodulation on the modulus signal to obtain a demodulated signal; A low-pass filter circuit, used for filtering the demodulated signal to obtain a metal particle signal; The first-stage amplifier circuit of the preamplifier circuit amplifies the sensing signal by 510 times through the amplifier chip U1 to obtain the first-stage amplified signal. The amplification factor is adjustable, and the calculation formula is: G1 is the gain of the first-stage amplifier circuit, R2 is the feedback resistor of the first-stage amplifier circuit, and R1 is the grounding resistor of the first-stage amplifier circuit; The second stage amplification circuit of the preamplification circuit amplifies the first stage amplification signal by 100 times through the amplification chip U2 to obtain the second stage amplification signal. The amplification factor is adjustable, and the calculation formula is: G2 is the gain of the second-stage amplifier circuit, R4 is the feedback resistor of the second-stage amplifier circuit, and R3 is the grounding resistor of the second-stage amplifier circuit; The preamplifier circuit includes an amplifier chip U1, an amplifier chip U2, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, and a capacitor C7; One end of the capacitor C5 is connected to one end of the capacitor C3 and then receives the induction signal. The other end of the capacitor C5 is grounded. The other end of the capacitor C3 is connected to the pin 3 of the amplifier chip U1 and the grounded resistor R6. The pin 4 of the amplifier chip U1 is connected to the grounded capacitor C6 and then connected to an external -15V power supply. The pin 2 of the amplifier chip U1 is connected to one end of the resistor R2 and the grounded resistor R1. The other end of the resistor R2 is connected to the pin 6 of the amplifier chip U1 as the first stage amplified signal output end. The pin 7 of the amplifier chip U1 is connected to the grounded capacitor C1 and then connected to an external +15V power supply. One end of the resistor R5 is connected to pin 6 of the amplifier chip U1, the other end of the resistor R5 is connected to the capacitor C4, the other end of the capacitor C4 is connected to pin 3 of the amplifier chip U2 and a grounded resistor R7, pin 4 of the amplifier chip U2 is connected to the grounded capacitor C7 and then connected to an external -15V power supply, pin 2 of the amplifier chip U2 is connected to one end of the resistor R4 and the grounded resistor R3, the other end of the resistor R4 is connected to pin 6 of the amplifier chip U2 as a second-stage amplified signal output end, and pin 7 of the amplifier chip U2 is connected to the grounded capacitor C2 and then connected to an external +15V power supply.

2. The inductive oil wear debris sensor modulus phase-sensitive detection demodulation system according to claim 1 is characterized in that: The modulus processing circuit includes an operational amplifier U3, an operational amplifier U4, a resistor R11, a resistor R8, a resistor R9, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a diode D3, and a diode D4; one end of the resistor R11 is connected to the second-stage amplified signal, the other end of the resistor R11 is connected to pin 2 of the operational amplifier U3, one end of the resistor R8 is connected to pin 2 of the operational amplifier U3, the other end of the resistor R8 is connected to the positive electrode of the diode D3 and one end of the resistor R9, the other end of the resistor R9 is connected to pin 2 of the operational amplifier U4 and one end of the resistor R10, and the other end of the resistor R10 is connected to the operational amplifier U4. Pin 6 of the operational amplifier U4 is connected to one end of the resistor R12, one end of the resistor R13 is connected to pin 2 of the operational amplifier U3, the other end of the resistor R13 is connected to the cathode of the diode D4 and pin 3 of the operational amplifier U4, the cathode of the diode D3 is connected to the anode of the diode D4 and pin 6 of the operational amplifier U3, pin 3 of the operational amplifier U3 is grounded, pin 4 of the operational amplifier U3 is externally connected to a -15V power supply, pin 7 of the operational amplifier U3 is externally connected to a +15V power supply, pin 4 of the operational amplifier U4 is externally connected to a -15V power supply, pin 7 of the operational amplifier U4 is externally connected to a +15V power supply, and pin 6 of the operational amplifier U4 outputs a modulus signal.

3. The inductive oil wear debris sensor modulus phase-sensitive detection demodulation system according to claim 2 is characterized in that: The modulus processing circuit receives the second-stage amplified signal. When the input signal is in the positive half cycle, the diode D3 is turned on, the diode D4 is turned off, and the reverse input terminal of the operational amplifier U3 is 0. Due to the virtual disconnection, no current flows into the same-direction input terminal of the operational amplifier U4, so the current can only take the AB path. At this time, Vout = Vin; when the input signal is in the negative half cycle, the diode D3 is turned off, the diode D4 is turned on, and the reverse input terminal of the operational amplifier U3 is 0. At this time, there are two paths for the current flowing from the reverse input terminal to the signal terminal. The first path is from point B through the resistor R 9 then passes through resistor R8 to pin 2 of op amp U3. The second line is output from pin 6 of op amp U3 through resistor R13 to pin 2 of op amp U3. Due to the virtual short, the potential of point B is equal to that of pin 3 of op amp U4. At this time, the voltage of point B is obtained according to Kirchhoff's current law. Since resistors R8, R9, R10 and op amp U4 form a unidirectional amplifier with a gain of 3 / 2, Vout = Vin; wherein: Vin is the signal input of the analog value processing circuit; Vout is the signal output of the analog value processing circuit.

4. The inductive oil wear debris sensor modulus phase-sensitive detection demodulation system according to claim 1 is characterized in that: The signal demodulation circuit performs phase-sensitive detection demodulation on the signal after the modulus processing to obtain a demodulated signal; according to the analog multiplier type phase-sensitive detection demodulation method, the output u of the analog multiplier type phase-sensitive detector is obtained. p (t), is the product of the measured modulation signal x(t) and the reference signal r(t) of the two input signals, that is: u p (t)=x(t)r(t); Both x(t) and r(t) are sine waves. Assume that the modulated signal to be measured is: x(t) = V s cos(ω0t+θ); The reference signal is: r(t) = V r cos(ω0t); Where ω0 is the frequency of the measured modulated signal and the reference signal, and θ is the phase difference between the measured modulated signal and the reference signal; After calculation and simplification, we can get: u p (t)=x(t)r(t)=V s cos(ω0t+θ)V r cos(ω0t)=0.5V s V r cosθ+0.5V s V r cos(2ω0t+θ); The output signal after filtering is: u0(t)=0.5V s V r cosθ; Modulus phase-sensitive detection is equivalent to adjusting the reference signal to: Among them, a0 is the DC component after being expanded into Fourier series, a m are the Fourier coefficients of the cosine components, b m are the Fourier coefficients of the sinusoidal components; After calculation and simplification, the output signal is: Where: u0(t) is the output voltage signal, V s is the amplitude of the modulated signal being measured, V r is the amplitude of the reference signal.

5. The inductive oil wear debris sensor modulus phase-sensitive detection demodulation system according to claim 1 is characterized in that: The signal demodulation circuit includes a chip U5, a resistor R12, a capacitor C9, and a capacitor C14; one end of the resistor R12 is connected to the analog value signal, and the other end of the resistor R12 is connected to pin 1, pin 10, and pin 16 of the chip U5. Pin 8 of the chip U5 is connected to the grounded capacitor C9 and then connected to an external -15V power supply. Pin 9 of the chip U5 is grounded. Pin 11 of the chip U5 is connected to the grounded capacitor C14 and then connected to an external +15V power supply. Pin 14 and pin 17 of the chip U5 are grounded, and pin 15, pin 19, and pin 20 of the chip U5 are connected.

6. The inductive oil wear debris sensor modulus phase-sensitive detection demodulation system according to claim 1 is characterized in that: The low-pass filter circuit uses a fourth-order low-pass filter to filter the demodulated signal to obtain a metal particle signal. The low-pass frequency is adjustable, and the calculation formula is: Where: f0 is the cut-off frequency, R is the resistance value, and C is the capacitance value.

7. The inductive oil wear debris sensor modulus phase-sensitive detection demodulation system according to claim 1 is characterized in that: The low-pass filter circuit includes a chip U6, a resistor R14, a resistor R15, a resistor R16, a resistor R20, a resistor R25, a capacitor C8, a capacitor C10, a capacitor C11, a capacitor C12, a capacitor C13, a capacitor C15, and a capacitor C16; one end of the resistor R14 is connected to the chip end signal, the other end of the resistor R14 is connected to one end of the capacitor C10 and one end of the resistor R15, the other end of the capacitor C10 is connected to pin 1 of the chip U6, the other end of the resistor R15 is connected to the grounded capacitor C12 and pin 3 of the chip U6, and pin 4 of the chip U6 is connected to the grounded capacitor C13 and then connected to an external -15V power supply, one end of the resistor R20 is connected to pin 1 and pin 2 of the chip U6, the other end of the resistor R20 is connected to one end of the capacitor C11 and one end of the resistor R16, the other end of the capacitor C11 is connected to pin 7 of the chip U6 and one end of the capacitor C16, the other end of the resistor R16 is connected to the grounded capacitor C15 and pin 5 of the chip U6, pin 1 and pin 2 of the chip U6 are connected, pin 6 and pin 7 of the chip U6 are connected, pin 8 of the chip U6 is connected to the grounded capacitor C8 and then connected to an external +15V power supply, and the other end of the capacitor C16 is connected to the grounded resistor R25.

8. A method for modulus phase-sensitive detection and demodulation of an inductive oil wear debris sensor, characterized in that: The inductive oil wear chip sensor modulus phase-sensitive detection demodulation system according to any one of claims 1 to 7 is implemented, and the inductive oil wear chip sensor modulus phase-sensitive detection demodulation method comprises: S1. Amplify the sensing signal through the preamplifier circuit to obtain an amplified signal; S2. Performing modulus processing on the amplified signal through a modulus processing circuit to obtain a modulus signal; S3. Perform phase-sensitive detection demodulation on the modulus signal through a signal demodulation circuit to obtain a demodulated signal; S4. Filter the demodulated signal through a low-pass filter circuit to obtain a metal particle signal.

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