An inductive oil abrasion debris sensor module value phase-sensitive detection demodulation system and method

Abstract

The application provides an inductive oil abrasion sensor module value phase-sensitive detection demodulation system and method, and belongs to the technical field of inductive oil abrasion sensors. The system comprises: a preamplification circuit, which is used for amplifying an induction signal to obtain an amplified signal; a module value processing circuit, which is used for processing the amplified signal in a module value mode to obtain a module value signal; a signal demodulation circuit, which is used for performing phase-sensitive detection demodulation on the module value signal to obtain a demodulated signal; and a low-pass filter circuit, which is used for filtering the demodulated signal to obtain a metal particle signal. The application can be applied to the sensor signal processing part of online oil abrasion monitoring, has simple circuit, fast operation speed, and convenient application, can obtain an output voltage with a larger amplitude, and is beneficial to reducing cost and improving the working speed of the system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of inductive oil debris sensors, in particular to an inductive oil debris sensor module value phase-sensitive detection demodulation system and method. BACKGROUND

[0002] In modern industry and mechanical equipment, monitoring of metal debris in lubricating oil is a key health monitoring technology. By detecting and analyzing metal debris in oil, signs of wear, corrosion and failure of mechanical parts can be detected in a timely manner, thereby preventing maintenance and avoiding sudden equipment failure and economic losses. In the fields of aerospace, automobile manufacturing, power generation equipment, etc., oil debris monitoring has been widely used and is an important means to ensure the safe and stable operation of equipment.

[0003] Traditional oil debris monitoring methods, such as optical detection and ultrasonic detection, have certain limitations, such as inability to detect in real time, low sensitivity or high cost. In contrast, inductive oil 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 susceptible to environmental noise interference, how to effectively extract and process these weak signals becomes a key challenge to improve the accuracy and reliability of the monitoring system. SUMMARY

[0004] The present application provides an inductive oil debris sensor module value phase-sensitive detection demodulation system and method, which aims to distinguish the phase of the modulated signal through a phase-sensitive detection circuit, and then determine the change in the measured phase, thereby distinguishing the properties of metal particles. At the same time, the phase-sensitive detection circuit also has the ability to select frequency, improving the anti-interference ability of the sensor circuit. Compared with traditional analog multiplier phase-sensitive detectors, the module value phase-sensitive detection demodulation has a large dynamic range, strong anti-overload ability, simplified circuit design, improved signal conditioning circuit stability, and is conducive to reducing costs and improving system speed.

[0005] The present application discloses an inductive oil debris sensor module value phase-sensitive detection demodulation system, comprising:

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

[0007] A module value processing circuit is used to process the amplified signal to obtain a module value signal;

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

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

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

[0011]

[0012] G1 is the amplification multiple of the first-stage amplification circuit, R2 is the feedback resistance of the first-stage amplification circuit, and R1 is the grounding resistance of the first-stage amplification circuit;

[0013] The second-stage amplification circuit of the preamplifier circuit amplifies the first-stage amplified signal by 100 times through an amplification chip U2 to obtain a second-stage amplified signal, and the amplification multiple is adjustable, and the calculation formula is:

[0014]

[0015] G2 is the amplification multiple of the second-stage amplification circuit, R4 is the feedback resistance of the second-stage amplification circuit, and R3 is the grounding resistance of the second-stage amplification circuit;

[0016] The preamplifier circuit comprises an amplification chip U1, an amplification chip U2, resistors R1, R2, R3, R4, R5, R6 and R7, and capacitors C1, C2, C3, C4, C5, C6 and C7.

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

[0018] In the specification, the module value processing circuit includes operational amplifier U3, operational amplifier U4, resistor R11, resistor R8, resistor R9, resistor R10, resistor R11, resistor R12, resistor R13, diode D3, diode D4; one end of the resistor R11 is connected to the second stage amplification 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, the other end of the resistor R10 is connected to pin 6 of the operational amplifier U4 and 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 negative electrode of the diode D4 and pin 3 of the operational amplifier U4, the negative electrode of the diode D3 is connected to the positive electrode 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 a-15V power supply, pin 7 of the operational amplifier U3 is connected to a+15V power supply, pin 4 of the operational amplifier U4 is connected to a-15V power supply, pin 7 of the operational amplifier U4 is connected to a+15V power supply, and pin 6 of the operational amplifier U4 outputs a module value signal.

[0019] In the specification, the module value processing circuit receives the second stage amplification signal, when the input signal is a positive half cycle, the diode D3 is turned on, the diode D4 is turned off, the reverse input end of the operational amplifier U3 is 0, due to virtual break, the same direction input end of the operational amplifier U4 does not flow current, so the current can only go through the AB path, at this time Vout=Vin; when the input signal is a negative half cycle, the diode D3 is turned off, the diode D4 is turned on, the reverse input end of the operational amplifier U3 is 0, at this time the current flowing from the reverse input end to the signal end has two main paths, the first path is from B point through the resistor R9 and then through the resistor R8 to pin 2 of the operational amplifier U3, the second path is from pin 6 of the operational amplifier U3 output, flows through the resistor R13 to pin 2 of the operational amplifier U3, due to virtual short, the potential of B point and pin 3 of the operational amplifier U4 is equal, at this time the B point voltage can be obtained according to Kirchhoff's current law, since the resistor R8, the resistor R9, the resistor R10 and the operational amplifier U4 constitute a same direction amplifier with a gain of 3 / 2, so Vout=Vin; wherein: Vin is the signal input of the module value processing circuit; Vout is the signal output of the module value processing circuit.

[0020] In the specification, the signal demodulation circuit carries out phase sensitive detection demodulation on the module value processed signal to obtain a demodulation signal; according to the analog multiplier type phase sensitive detection demodulation method, the output u p (t) of the analog multiplier type phase sensitive detector is the product of the two input signals, i.e.: up (t) = x(t) r(t);

[0021] x(t) and r(t) are both sine waves, and suppose the measured modulation signal is: x(t) = V s cos(ω0t + θ);

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

[0023] Wherein, ω0 is the frequency of the measured modulation signal and the reference signal, and θ is the phase difference of the measured modulation 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) = 0.5 V s V r cosθ + 0.5 V s V r cos(2ω0t + θ);

[0026] The output signal obtained after filtering is:

[0027] u0(t) = 0.5 V s V r cosθ;

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

[0029]

[0030] Wherein, a0 is the direct current 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 sine component, and ω0 is the angular frequency;

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

[0032]

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

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

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

[0036]

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

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

[0039] The specification also discloses a kind of induction type oil liquid abrasion sensor module value phase-sensitive detection demodulation method, it is realized by induction type oil liquid abrasion sensor module value phase-sensitive detection demodulation system described in any one of the above, the induction type oil liquid abrasion sensor module value phase-sensitive detection demodulation method comprises:

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

[0041] S2. Perform 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 the present specification can at least achieve the following beneficial effects:

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

[0046] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0047] Figure 1 It is a schematic diagram of the induction type oil abrasion sensor modulus phase-sensitive detection demodulation system involved in the present application.

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

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

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

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

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

[0053] Figure 7 It is a comparison schematic diagram of the analog multiplier type phase-sensitive detection and the modulus processing phase-sensitive detection output signal involved in the present application. DETAILED DESCRIPTION

[0054] Hereinafter, only certain exemplary embodiments are briefly described. As will be appreciated by those skilled in the art, 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 description are to be regarded as illustrative in nature and not restrictive.

[0055] The disclosure below provides many different embodiments or examples for implementing different structures of the embodiments of the present invention. In order to simplify the disclosure of the embodiments of the present invention, the components and configurations of specific examples are described below. Of course, these are merely examples and are not intended to limit the embodiments of the present invention. In addition, the embodiments of the present invention may repeat reference numerals and / or reference letters in different examples. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or configurations 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 debris 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, configured to perform 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 amplification factor 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 amplifier circuit of the preamplifier circuit amplifies the first-stage amplified signal by 100 times through the amplifier chip U2 to obtain the second-stage amplified signal. The amplification factor is adjustable, and the calculation formula is:

[0066]

[0067] G2 is the amplification factor of the second-stage amplification circuit, R4 is the feedback resistance of the second-stage amplification circuit, and R3 is the grounding resistance of the second-stage amplification circuit;

[0068] As shown in Figure 2 , the preamplification circuit includes an amplification chip U1, an amplification 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 connected to the sensing 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 amplification chip U1 and the resistor R6 grounded, the pin 4 of the amplification chip U1 is connected to the capacitor C6 grounded and then connected to a -15V power supply externally, the pin 2 of the amplification chip U1 is connected to one end of the resistor R2 and the resistor R1 grounded, the other end of the resistor R2 is connected to the pin 6 of the amplification chip U1 and then serves as a first-stage amplification signal output end, the pin 7 of the amplification chip U1 is connected to the capacitor C1 grounded and then connected to a +15V power supply externally, one end of the resistor R5 is connected to the pin 6 of the amplification 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 the pin 3 of the amplification chip U2 and the resistor R7 grounded, the pin 4 of the amplification chip U2 is connected to the capacitor C7 grounded and then connected to a -15V power supply externally, the pin 2 of the amplification chip U2 is connected to one end of the resistor R4 and the resistor R3 grounded, the other end of the resistor R4 is connected to the pin 6 of the amplification chip U2 and then serves as a second-stage amplification signal output end, and the pin 7 of the amplification chip U2 is connected to the capacitor C2 grounded and then connected to a +15V power supply externally.

[0070] In some embodiments, as Figure 3As shown, the modulus processing circuit includes operational amplifier U3, operational amplifier U4, resistor R11, resistor R8, resistor R9, resistor R10, resistor R11, resistor R12, resistor R13, diode D3, 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 anode 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, the other end of the resistor R10 is connected to pin 6 of the operational amplifier U4 and 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 a -15V power supply, pin 7 of the operational amplifier U3 is connected to a +15V power supply, pin 4 of the operational amplifier U4 is connected to a -15V power supply, pin 7 of the operational amplifier U4 is connected to a +15V power supply, pin 6 of the operational amplifier U4 outputs the modulus signal.

[0071] In some embodiments, the modulus processing circuit receives the second stage amplified signal, when the input signal is positive half cycle, the diode D3 is turned on, the diode D4 is turned off, the reverse input end of the operational amplifier U3 is 0, due to virtual break, the same direction input end of the operational amplifier U4 does not flow current, so the current can only go through the AB path, at this time Vout=Vin; when the input signal is negative half cycle, the diode D3 is turned off, the diode D4 is turned on, the reverse input end of the operational amplifier U3 is 0, at this time the current flowing from the reverse input end to the signal end has two main paths, the first path is from B point through R9 and then through R8 to pin 2 of U3, the second path is from pin 6 of U3 output and flows through R13 to pin 2 of U3, due to virtual short, the potential of B point and pin 3 of U4 is equal, at this time the B point voltage can be obtained according to Kirchhoff's current law, since the resistor R8, the resistor R9, the resistor R10 and the operational amplifier U4 constitute a same direction amplifier with a gain of 3 / 2, so Vout=Vin; wherein: Vin is the signal input of the modulus processing circuit; Vout is the signal output of the modulus processing circuit.

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

[0073] x(t) and r(t) are sinusoidal waves, and let the measured modulation signal be: 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 modulation signal and the reference signal, and θ is the phase difference of the measured modulation 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) = 0.5 V s V r cosθ + 0.5 V s V r cos(2ω0t+θ) ;

[0078] The output signal obtained after filtering is:

[0079] u0(t) = 0.5 V s V r cosθ ;

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

[0081]

[0082] where a0 is the direct current component after expansion into Fourier series, a m is the Fourier coefficient of the cosine component, b m is the Fourier coefficient of the sine component, and 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 measured modulation signal, and V r is the amplitude of the reference signal.

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

[0087] In some embodiments, the low-pass filter circuit adopts four-order low-pass filter to filter the demodulation signal to obtain the metal particle signal, and the low-pass frequency is adjustable, and the calculation formula is:

[0088]

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

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

[0091] The embodiment of the present specification also provides a demodulation method for a module value phase-sensitive detection of an inductive oil abrasion debris sensor, which is realized by the inductive oil abrasion debris sensor module value phase-sensitive detection demodulation system in any one of the above, and the demodulation method comprises the following steps:

[0092] S1. The inductive signal is amplified by a preamplifier circuit to obtain an amplified signal;

[0093] S2. The amplified signal is processed by a module value processing circuit to obtain a module value signal;

[0094] S3. The module value signal is phase-sensitive detection demodulated by a signal demodulation circuit to obtain a demodulated signal;

[0095] S4. The demodulated signal is filtered by a low-pass filter circuit to obtain a metal particle signal.

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

[0097] As shown in Figure 1 , the present application processes the sensor output signal, so that the signal enters the preamplification part, the signal is amplified by the two-stage amplifier of OPA627 and OP37, and the amplitude and definition of the signal are enhanced; then, the signal passing through the module value processing circuit is sent to the demodulation part, the phase demodulation is performed by using AD630, and the effective signal is extracted; the demodulated signal is filtered by the low-pass filter to remove the high-frequency noise, and the smooth signal output is obtained; finally, the processed signal is output from the output end, and a stable signal output is provided for subsequent analysis.

[0098] As shown in Figure 3 , the module value processing circuit processes the input signal in the module value, and constitutes a module value phase-sensitive detection circuit with the signal demodulation circuit as shown in Figure 4 .

[0099] The module value phase-sensitive detection is a signal demodulation method based on and optimized from the analog multiplier type phase-sensitive detection, which can improve the amplitude and stability of the output signal. The output u p (t) of the analog multiplier type phase-sensitive detector is the product of its two input signals (the measured modulation 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), and the reference input is r(t)=V r cos(ω0t), wherein ω0 is the frequency of the measured modulation signal and the reference signal, and θ is the phase difference between them. After calculation and simplification, 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 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 can be larger, while the structure is simpler and the stability is higher.

[0100] like Figure 6 As shown in the figure, after the pre-amplified signal is modulated, the original signal waveform and the waveform after modulo processing are compared, and it can be found that the signals are both 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, 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, and 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-sensitive detection circuit distinguishes the phase of the modulated signal, and then determines the phase change of the measured value, 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 embodiments are intended to illustrate the present invention, not to limit the present invention. Therefore, changes in illustrative values ​​or substitutions of equivalent components should still fall within the scope of the present invention.

[0104] From the above detailed description, it will be clear to 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] While the preferred embodiments of the application have been described, additional variations and modifications can be made to these embodiments by those skilled in the art once they have the benefit of the foregoing description. It is intended that the appended claims shall cover all such modifications and changes as fall within the true spirit and scope of the application. The above description is therefore not to be taken in a limiting sense. It is to be understood that features of the embodiments of the application can be combined, substituted, or modified, where appropriate, with features of other embodiments, without departing from the scope of the present application.

[0106] It should be noted that the description of the flow is merely illustrative and explanatory and does not limit the scope of the present specification. Various modifications and changes can be made to the flow by those skilled in the art under the guidance of the present specification. However, these modifications and changes are still within the scope of the present specification.

[0107] The above description has described the basic concepts, and it is obvious to those skilled in the art after reading this application that the above disclosure of the application is only as an example and does not constitute a limitation on the present application. Although it is not explicitly stated here, those skilled in the art can make various modifications, improvements and modifications to the present application. Such modifications, improvements and modifications are suggested in the present application, so such modifications, improvements and modifications are still within the spirit and scope of the exemplary embodiments of the present application.

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

[0109] In addition, those skilled in the art can understand that aspects of the present application can be described and illustrated by several patentable categories or cases, including any new and useful processes, machines, products or combinations of matter, or any new and useful improvements to them. Therefore, various aspects of the present application can 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 can be referred to as "unit", "module" or "system". In addition, aspects of the present application can 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] Computer program code for carrying out operations of various aspects of the present application can be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Scala, Smalltalk, Eiffel, JADE, Emerald, C++, C#, VB.NET, Python, conventional procedural programming languages, such as the C programming language, Visual Basic, Fortran 2103, Perl, COBOL 2102, PHP, ABAP, dynamic programming languages, such as Python, Ruby and Groovy, or another programming language. The program code can execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer can be connected to the user's computer through any form of network, such as a local area network (LAN) or a wide area network (WAN), or the connection can be made to an external computer (for example, through the Internet) or within a cloud computing environment or as a service, such as software as a service (SaaS).

[0111] Furthermore, the order of presentation of the processing elements and sequences, use of nomenclature, or other descriptive terms herein are not intended to limit the scope of the embodiments or the application in any way. Although the above disclosure discusses some presently preferred embodiments of the application, and although various configurations have been set forth, it is understood that the embodiments maybe embodied with various changes, substitutions, and equivalents, without departing from the spirit and essential scope of this application. For example, although the implementation of the various components described above can be embodied in hardware, it can also be embodied in software that is installed on an existing server or mobile device.

[0112] Similarly, it is to be noticed that the term "comprising", used in the description, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression should be commensurate to the disclosure and defined by the claims. Moreover, although the application has been described in some regard with reference to only a limited number of embodiments, it is clear that the scope of the application is not limited to the described embodiments, but rather covers all possible embodiments falling within the scope of the present application.

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, configured to perform 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 amplification factor 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 amplifier circuit of the preamplifier circuit amplifies the first-stage amplified signal by 100 times through the amplifier chip U2 to obtain the second-stage amplified signal. The amplification factor is adjustable, and the calculation formula is: ； G2 is the amplification factor 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 pin 3 of the amplifier chip U1 and the grounded resistor R6. Pin 4 of the amplifier chip U1 is connected to the grounded capacitor C6 and then connected to an external -15V power supply. 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 pin 6 of the amplifier chip U1. After the connection, it serves 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 the 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 the pin 3 of the amplifier chip U2 and the grounded resistor R7, the pin 4 of the amplifier chip U2 is connected to the grounded capacitor C7 and then connected to an external -15V power supply, the 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 the pin 6 of the amplifier chip U2 and serves as the second-stage amplified signal output end, the pin 7 of the amplifier chip U2 is connected to the grounded capacitor C2 and then connected to an external +15V power supply; 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 op amp U4 is connected to one end of the resistor R12, one end of the resistor R13 is connected to pin 2 of the op amp U3, the other end of the resistor R13 is connected to the cathode of the diode D4 and pin 3 of the op amp U4, the cathode of the diode D3 is connected to the anode of the diode D4 and pin 6 of the op amp U3, pin 3 of the op amp U3 is grounded, pin 4 of the op amp U3 is externally connected to a -15V power supply, pin 7 of the op amp U3 is externally connected to a +15V power supply, pin 4 of the op amp U4 is externally connected to a -15V power supply, pin 7 of the op amp U4 is externally connected to a +15V power supply, and pin 6 of the op amp U4 outputs a modulus signal.

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 receives the second-stage amplified signal. When the input signal is in the positive half cycle, the diode D3 is turned on and the diode D4 is turned off. 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 and the diode D4 is turned on. 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 R9 and then through the resistor R8 to the pin 2 of the operational amplifier U3. The second path is output from the pin 6 of the operational amplifier U3 through the resistor R13 to the pin 2 of the operational amplifier U3. Due to the virtual short, the potential of point B and the pin 3 of the operational amplifier U4 are equal. At this time, the voltage at point B is obtained according to Kirchhoff's current law. Since the resistors R8, R9, R10 and the operational amplifier U4 form a same-direction amplifier with a gain of 3 / 2, Vout =Vin; where: Vin is the signal input of the analog value processing circuit; Vout is the signal output of the analog value processing circuit.

3. 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 of the analog multiplier type phase-sensitive detector is obtained. , are the two input signals and the modulated signals to be measured and reference signal The product of , that is: ; and All are sine waves. Assume that the modulated signal to be measured is: ; The reference signal is: ; in, are the frequencies of the modulated signal under test and the reference signal, is the phase difference between the modulated signal under test and the reference signal; After calculation and simplification, we can get: ； The output signal after filtering is: ； Modulus phase-sensitive detection is equivalent to adjusting the reference signal to: ； in, is the DC component after being expanded into a Fourier series, are the Fourier coefficients of the cosine components, are the Fourier coefficients of the sinusoidal components; After calculation and simplification, the output signal is: ； in: is the output voltage signal, is the amplitude of the modulated signal being measured, is the amplitude of the reference signal.

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 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.

5. The inductive oil wear debris sensor modulus phase-sensitive detection and 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: ； in: is the cutoff frequency, is the resistance value, is the capacitance value.

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 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 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 the 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.

7. A method for modulus phase-sensitive detection and demodulation of an inductive oil wear debris sensor, characterized in that: The method is implemented by the inductive oil wear debris sensor modulus phase-sensitive detection and demodulation system according to any one of claims 1 to 6, wherein the inductive oil wear debris sensor modulus phase-sensitive detection and demodulation method comprises: S1. Amplify the sensing signal through a preamplifier circuit to obtain an amplified signal; S2. Modulus processing circuit performs modulus processing on the amplified signal to obtain a modulus signal; S3. Phase-sensitive demodulation is performed on the modulus signal by the 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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