An oil metal debris monitoring device and method

Abstract

The application discloses a lubricating oil metal debris monitoring device and method, which is applied to the technical field of signal detection and comprises a lubricating oil metal debris sensor, an excitation circuit, a routing circuit, an analog-digital conversion circuit, a collection circuit for outputting a received induction signal to the analog-digital conversion circuit after demodulation and amplification, and a processing circuit for applying an excitation signal through the excitation circuit in an adaptation mode, obtaining an induction signal from the lubricating oil metal debris sensor output by a first output end of the routing circuit through the analog-digital conversion circuit, and determining a phase difference between the excitation signal and the induction signal; in a monitoring mode, a reference signal for demodulation is generated based on the phase difference and sent to the collection circuit, and a detection result of the metal debris is obtained by analyzing an output signal of the analog-digital conversion circuit. The scheme of the application can be flexibly adapted to lubricating oil metal debris sensors of different manufacturers.

Description

Technical Field

[0001] This invention relates to the field of signal detection technology, and in particular to a device and method for monitoring lubricating oil metal shavings. Background Technology

[0002] The power system provides power to machinery. For example, the aircraft turbine engine provides power to the aircraft and is one of the important systems on the aircraft. The rotor speed of the turbine engine is as high as tens of thousands of revolutions per minute. Important components such as rotor support bearings, drive shafts, gears, and oil pumps operate in harsh environments with high temperature, high speed, high load, and alternating stress. The failure rate is high, and once these components wear abnormally, they may fail rapidly, leading to structural failure of the engine, a sharp drop or loss of aircraft thrust, or even a flight accident.

[0003] Lubricating oil metal shavings monitoring technology analyzes the metal shavings in the lubricating oil of the monitored equipment to obtain health information of the power system, thereby analyzing and predicting equipment failures and determining the cause, type, and location of the failure. Taking advantage of the ferromagnetic nature of wear metal shavings, a magnetoelectric online lubricating oil metal shavings monitoring sensor has been developed, which is currently a relatively successful method. The lubricating oil metal shavings monitoring device consists of a sensor, connecting cable, and demodulator; see reference [link / reference needed]. Figure 1 This is a schematic diagram of the structure of a lubricating oil metal shavings sensor. It consists of a pair of reverse-wound coils and a parallel capacitor forming an LC resonant system. An excitation signal is provided by a demodulator, which creates a balanced magnetic field in the middle of the two coils. An induction coil is placed between the two excitation coils to sense the magnetic field disturbance when metal particles pass through the solenoid, thereby realizing the detection of metal shavings.

[0004] For this type of sensor probe, although the sensor principles of different manufacturers are the same, the signal-to-noise ratio and phase angle are not completely consistent. Therefore, it is difficult to achieve a unified measurement standard for metal particles. In other words, each manufacturer's sensor can only be adapted to its own demodulator to realize its online monitoring function, resulting in high cost, insufficient flexibility and reduced reliability.

[0005] In summary, how to effectively monitor lubricating oil metal shavings and ensure the flexibility and reliability of the application is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a device and method for monitoring lubricating oil metal shavings, so as to effectively monitor lubricating oil metal shavings and ensure the flexibility and reliability of the application.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a lubricating oil metal shavings monitoring device, comprising: A lubricating oil metal shavings sensor used to detect metal shavings in lubricating oil and output a sensing signal; An excitation circuit for applying an excitation signal to the lubricating oil metal shavings sensor under the control of the processing circuit; Both the first and second input terminals are connected to the output terminal of the lubricating oil metal shavings sensor, forming a routing circuit for signal routing. An analog-to-digital converter circuit connected to the first output terminal of the routing circuit for performing analog-to-digital conversion; The acquisition circuit, whose input terminal is connected to the second output terminal of the routing circuit and whose output terminal is connected to the analog-to-digital conversion circuit, is used to demodulate and amplify the received induced signal based on the reference signal and then output it to the analog-to-digital conversion circuit. In adaptation mode, the processing circuit applies an excitation signal through the excitation circuit and obtains the sensing signal from the lubricating oil metal shavings sensor output from the first output terminal of the routing circuit through the analog-to-digital converter circuit, and determines the phase difference between the excitation signal and the sensing signal; in monitoring mode, it generates a reference signal for demodulation based on the phase difference and sends it to the acquisition circuit, and obtains the detection result of metal shavings by analyzing the output signal of the analog-to-digital converter circuit. The first input terminal of the routing circuit is connected to the first output terminal of the routing circuit, and the second input terminal of the routing circuit is connected to the second output terminal of the routing circuit.

[0008] In one embodiment, the acquisition circuit includes: A preamplifier circuit used to initially amplify the received induced signal; A demodulation circuit connected to the preamplifier circuit is used to demodulate the output signal of the preamplifier circuit based on a reference signal. The output signal of the demodulation circuit is connected to the analog-to-digital converter circuit and the high-pass filter amplifier circuit, respectively, so that in the monitoring mode, when the sensed signal is a large particle signal, the processing circuit detects metal shavings based on the output signal of the demodulation circuit, and when the sensed signal is a small particle signal, the processing circuit detects metal shavings based on the output signal of the high-pass filter amplifier circuit. A high-pass filter amplifier circuit is used to perform high-pass filtering and amplification on the output signal of the demodulation circuit; Specifically, when the amplitude of the particle signal in the sensing signal reaches a preset first threshold, the sensing signal belongs to a large particle signal; when the amplitude of the particle signal in the sensing signal is not greater than the first threshold, the sensing signal belongs to a small particle signal.

[0009] In one embodiment, the demodulation circuit is a single-channel demodulation circuit, and it demodulates the in-phase reference signal and the quadrature reference signal in the reference signal by time-division multiplexing.

[0010] In one embodiment, the demodulation circuit is a dual-channel demodulation circuit, and the demodulation circuit includes: The input terminal is connected to the output terminal of the preamplifier circuit, and is used to amplify the input signal by a factor of K; where K represents the amplification factor. The input terminal is connected to the output terminal of the pre-amplifier circuit, and is used to amplify the input signal by a factor of -K in the second amplifier circuit. A first switching circuit has its input terminal connected to the output terminal of the first amplifier circuit and its output terminal connected to the input terminal of the first low-pass filter circuit. The control terminal of the first switching circuit is used to receive the in-phase component reference signal in the reference signal, so as to control the on / off state of the first switching circuit through the in-phase component reference signal. A second switching circuit has its input terminal connected to the output terminal of the second amplifier circuit and its output terminal connected to the input terminal of the second low-pass filter circuit. The control terminal of the second switching circuit is used to receive the quadrature component reference signal in the reference signal, so as to control the on / off state of the second switching circuit through the quadrature component reference signal. The input terminal of the first low-pass filter circuit is connected to the output terminal of the first switching circuit. The input terminal is connected to the output terminal of the second low-pass filter circuit.

[0011] In one embodiment, the first amplifier circuit includes: a first operational amplifier, a first resistor, and a second resistor; the second amplifier circuit includes: a second operational amplifier, a third resistor, and a fourth resistor; The non-inverting input of the first operational amplifier is used as the input of the first amplifier circuit to connect to the output of the preamplifier circuit. The inverting input of the first operational amplifier is connected to the second end of the first resistor and the first end of the second resistor, respectively. The first end of the first resistor is grounded, and the second end of the second resistor is connected to the output of the first operational amplifier, with the connection end serving as the output of the first amplifier circuit. The first end of the third resistor serves as the input terminal of the second amplifier circuit and is connected to the output terminal of the preamplifier circuit. The second end of the third resistor is connected to the inverting input terminal of the second operational amplifier and the first end of the fourth resistor, respectively. The non-inverting input terminal of the second operational amplifier is grounded. The output terminal of the second operational amplifier is connected to the second end of the fourth resistor, and the connection terminal serves as the output terminal of the second amplifier circuit.

[0012] In one embodiment, the first low-pass filter circuit includes: a third operational amplifier, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a first capacitor, a second capacitor, and a third capacitor. The first terminal of the fifth resistor serves as the input terminal of the first low-pass filter circuit. The second terminal of the fifth resistor is connected to the first terminal of the first capacitor and the first terminal of the sixth resistor. The second terminal of the sixth resistor is connected to the first terminal of the seventh resistor and the first terminal of the second capacitor. The second terminal of the seventh resistor is connected to the first terminal of the third capacitor and the non-inverting input terminal of the third operational amplifier. The second terminal of the first capacitor is grounded, and the second terminal of the third capacitor is grounded. The inverting input terminal of the third operational amplifier is connected to the first terminal of the eighth resistor and the first terminal of the ninth resistor, respectively. The second terminal of the eighth resistor is grounded. The output terminal of the third operational amplifier is connected to the second terminal of the ninth resistor and the second terminal of the second capacitor, and the connection terminal serves as the output terminal of the first low-pass filter circuit.

[0013] In one embodiment, the high-pass filter amplifier circuit is a dual-channel high-pass filter amplifier circuit, and the high-pass filter amplifier circuit includes: A first high-pass filter circuit whose input terminal is connected to the output terminal of the first low-pass filter circuit; A third amplifier circuit whose input terminal is connected to the output terminal of the first high-pass filter circuit and whose output terminal is connected to the analog-to-digital converter circuit; A second high-pass filter circuit whose input terminal is connected to the output terminal of the second low-pass filter circuit; The input terminal is connected to the output terminal of the second high-pass filter circuit, and the output terminal is connected to the analog-to-digital converter circuit of the fourth amplifier circuit.

[0014] In one embodiment, the first high-pass filter circuit includes a fourth operational amplifier, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a fourteenth resistor, a fourth capacitor, a fifth capacitor, and a sixth capacitor. The first terminal of the fourth capacitor serves as the input terminal of the first high-pass filter circuit. The second terminal of the fourth capacitor is connected to the first terminal of the fifth capacitor and the first terminal of the tenth resistor. The second terminal of the tenth resistor is grounded. The second terminal of the fifth capacitor is connected to the first terminal of the sixth capacitor and the first terminal of the eleventh resistor. The second terminal of the sixth capacitor is connected to the first terminal of the twelfth resistor and the non-inverting input terminal of the fourth operational amplifier. The second terminal of the twelfth resistor is grounded. The inverting input terminal of the fourth operational amplifier is connected to the first terminal of the thirteenth resistor and the first terminal of the fourteenth resistor, respectively. The second terminal of the thirteenth resistor is grounded. The output terminal of the fourth operational amplifier is connected to the second terminal of the fourteenth resistor and the second terminal of the eleventh resistor, respectively, and the connection terminal serves as the output terminal of the first high-pass filter circuit.

[0015] In one embodiment, a fifth amplifier circuit is further provided between the first input terminal and the first output terminal of the routing circuit.

[0016] In one embodiment, the excitation circuit includes: a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, an eighteenth resistor, a fifth operational amplifier, and a first switching transistor; The first end of the fifteenth resistor serves as the control terminal of the excitation circuit and is connected to the processing circuit. The second end of the fifteenth resistor is connected to the non-inverting input terminal of the fifth operational amplifier and the first end of the sixteenth resistor. The inverting input terminal of the fifth operational amplifier is connected to a preset reference voltage. The output terminal of the fifth operational amplifier is connected to the second end of the sixteenth resistor and the control terminal of the first switching transistor. The second end of the first switching transistor is connected to the negative terminal of the first power supply. The first end of the first switching transistor is connected to the second end of the seventeenth resistor. The first end of the seventeenth resistor serves as the negative output terminal of the excitation circuit. The second end of the eighteenth resistor is connected to the positive terminal of the first power supply. The first end of the eighteenth resistor serves as the positive output terminal of the excitation circuit.

[0017] In one implementation, it further includes: A digital-to-analog converter circuit connected to the processing circuit, used to receive the simulation signal output by the processing circuit and output it to the third input terminal of the routing circuit after digital-to-analog conversion; The routing circuit also includes a switching switch. The first end of the switching switch serves as the second input terminal of the routing circuit, the second end of the switching switch serves as the third input terminal of the routing circuit, and the third end of the switching switch serves as the second output terminal of the routing circuit. In monitoring mode, the switching switch is in a first state, connecting the second input terminal and the second output terminal of the routing circuit. In simulation calibration mode, the switching switch is in a second state, connecting the third input terminal and the second output terminal of the routing circuit. The processing circuit is further configured to: in simulation calibration mode, send a first simulation signal to the third input terminal of the routing circuit for software calibration; in simulation calibration mode, send a second simulation signal to the third input terminal of the routing circuit for calibration of the low-pass filter circuit structure in the acquisition circuit; and in simulation calibration mode, send a third simulation signal to the third input terminal of the routing circuit for calibration of the high-pass filter circuit structure in the acquisition circuit.

[0018] In one embodiment, the first simulated signal is: the simulated induction signal generated by superimposing the particle signal output by the processing circuit through the particle signal generator and the carrier signal output by the processing circuit through the frequency synthesizer.

[0019] In one implementation, it further includes: The first input terminal is connected to the output terminal of the lubricating oil metal shavings sensor, the second input terminal is connected to the output terminal of the digital-to-analog converter circuit, and the output terminal is connected to the first input terminal of the routing circuit, which is used as a multiplier for signal superposition. The processing circuit is also used to: in simulation calibration mode, output a particle signal through a particle signal generator, and superimpose the particle signal output by the particle signal generator with the sensing signal output by the lubricating oil metal shavings sensor when no metal shavings are generated to obtain a fourth simulation signal for software calibration.

[0020] In one embodiment, the routing circuit further includes a fourth input terminal and a third output terminal, wherein the fourth input terminal of the routing circuit is connected to the third output terminal of the routing circuit, and the third output terminal of the routing circuit is connected to the analog-to-digital converter circuit, so that the output signal of the third output terminal of the routing circuit is sent to the processing circuit through the analog-to-digital converter circuit; the fourth input terminal of the routing circuit is connected to the excitation circuit. The processing circuit is also used in self-test mode to apply an excitation signal through the excitation circuit when performing an excitation circuit self-test, and to obtain the signal output by the third output terminal of the routing circuit through the analog-to-digital conversion circuit. When the signal output by the third output terminal of the routing circuit is abnormal, the excitation circuit self-test is determined to be abnormal. In self-test mode, when the sensing loop self-test is performed, an excitation signal is applied through the excitation circuit to control the self-test line of the sensing loop to be turned on, so that the excitation signal is applied to the output terminal of the lubricating oil metal shavings sensor through the self-test line of the sensing loop, and the signal output by the first output terminal of the routing circuit is obtained through the analog-to-digital conversion circuit. When the signal output by the first output terminal of the routing circuit is abnormal, it is determined that the self-test of the sensing loop is abnormal. The self-test circuit of the sensing circuit is connected between the output terminal of the excitation circuit and the output terminal of the lubricating oil metal shavings sensor, and is in an open circuit state by default, only in a conducting state during the self-test of the sensing circuit.

[0021] In one embodiment, when the excitation circuit self-test is performed, if the signal output from the third output terminal of the routing circuit is a DC signal, the processing circuit determines that the excitation circuit self-test is abnormal and the abnormality type is excitation circuit disconnection; if the signal output from the third output terminal of the routing circuit is a square wave signal, the processing circuit determines that the excitation circuit self-test is abnormal and the abnormality type is excitation circuit short circuit. When the induction circuit self-test is performed, if the signal output from the first output terminal of the routing circuit is a DC signal, the processing circuit determines that the induction circuit self-test is abnormal and the abnormality type is induction circuit disconnection; if the signal output from the first output terminal of the routing circuit is a square wave signal, the processing circuit determines that the induction circuit self-test is abnormal and the abnormality type is induction circuit short circuit.

[0022] In one embodiment, an attenuator is further provided between the fourth input terminal and the third output terminal of the routing circuit.

[0023] In a second aspect, the present invention provides a method for detecting lubricating oil metal shavings, applied to the processing circuit of the lubricating oil metal shavings monitoring device as described above, comprising: In the adaptation mode, an excitation signal is applied through the excitation circuit, and the induction signal from the lubricating oil metal shavings sensor is obtained through the analog-to-digital conversion circuit, and the phase difference between the excitation signal and the induction signal is determined. In monitoring mode, a reference signal for demodulation is generated based on the phase difference and sent to the acquisition circuit. The detection result of metal shavings is obtained by analyzing the output signal of the analog-to-digital conversion circuit.

[0024] Applying the technical solution provided in the embodiments of this invention, considering that if demodulation is performed directly using the excitation signal, the phase difference between the excitation signal and the sensing signal will lead to demodulation failure, and this phase difference may differ between different lubricating oil metal shavings sensors, this application's solution detects the phase difference in an adaptation mode, thereby achieving compensation. This allows the demodulator of this application's solution to be flexibly adapted to lubricating oil metal shavings sensors from different manufacturers.

[0025] Specifically, in the adaptation mode, an excitation signal is applied through the excitation circuit. The induced signal output by the lubricating oil metal shavings sensor can then be output through the first output terminal of the routing circuit and transmitted to the analog-to-digital converter circuit for analog-to-digital conversion. This signal is then received by the processing circuit, which determines the phase difference between the excitation signal and the induced signal, i.e., the phase offset between them. Based on this phase difference, a reference signal for demodulation is generated. In the monitoring mode, after the reference signal is sent to the acquisition circuit, demodulation is effectively achieved. Finally, the processing circuit accurately obtains the detection result of the metal shavings by analyzing the output signal of the analog-to-digital converter circuit. In summary, this application's solution determines the phase difference between the excitation signal and the induced signal through the adaptation mode, thereby generating a reference signal adapted to the current model of the lubricating oil metal shavings sensor, effectively achieving demodulation and ensuring the flexibility and reliability of this application's solution. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the structure of a lubricating oil metal shavings sensor; Figure 2 This is a schematic diagram of the structure of a lubricating oil metal shavings monitoring device provided in a specific embodiment of the present invention; Figure 3 A schematic diagram of the structure of a lubricating oil metal shavings monitoring device provided in another specific embodiment of the present invention; Figure 4 A characteristic diagram of the induced signal of lubricating oil metal shavings; Figure 5 This is a schematic diagram of the excitation circuit in another specific embodiment of the present invention; Figure 6 This is a schematic diagram of the connection structure of the acquisition circuit, routing circuit and processing circuit in one specific embodiment of the present invention; Figure 7 This is a schematic diagram of the preamplifier circuit in a specific embodiment of the present invention; Figure 8 This is a schematic diagram of the structure of the first amplifier circuit in a specific embodiment of the present invention; Figure 9 This is a schematic diagram of the structure of a first low-pass filter circuit in a specific embodiment of the present invention; Figure 10 This is a schematic diagram of the structure of a first high-pass filter circuit in a specific embodiment of the present invention; Figure 11 This is a schematic diagram of the routing circuit in a specific embodiment of the present invention; Figure 12 This is a schematic diagram of the structure of a simulation calibration mode implemented by a calibration circuit in a specific embodiment of the present invention; Figure 13 A schematic diagram of the lubricating oil metal shavings monitoring device provided in another specific embodiment of the present invention; Figure 14 This is a feature map of Fe and nFe particle signals generated by a particle signal generator in a specific embodiment of the present invention; Figure 15 This is a waveform diagram of the second simulated signal in a specific embodiment of the present invention; Figure 16 This is a waveform diagram of the third simulated signal in a specific embodiment of the present invention; Figure 17 This is a flowchart illustrating the implementation of a lubricating oil metal shavings monitoring method in a specific embodiment of the present invention. Detailed Implementation

[0028] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this application.

[0029] To enable those skilled in the art to better understand the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Please refer to Figure 2 , Figure 2 This is a schematic diagram of the structure of a lubricating oil metal shavings monitoring device according to a specific embodiment of the present invention. The lubricating oil metal shavings monitoring device may include: A lubricating oil metal shavings sensor 10 is used to detect metal shavings in lubricating oil and output a sensing signal. Excitation circuit 20 is used to apply an excitation signal to lubricating oil metal shaving sensor 10 under the control of processing circuit 60; Both the first and second input terminals are connected to the output terminal of the lubricating oil metal shavings sensor 10, which is used for the routing circuit 30 for signal routing. An analog-to-digital converter circuit 50 is connected to the first output terminal of the routing circuit 30 and is used for analog-to-digital conversion. The input terminal is connected to the second output terminal of the routing circuit 30, and the output terminal is connected to the analog-to-digital conversion circuit 50. The acquisition circuit 40 is used to demodulate and amplify the received induced signal based on the reference signal and then output it to the analog-to-digital conversion circuit 50. In the adaptation mode, the processing circuit 60 applies an excitation signal through the excitation circuit 20 and obtains the sensing signal from the lubricating oil metal shavings sensor 10 output by the first output terminal of the routing circuit 30 through the analog-to-digital converter circuit 50, and determines the phase difference between the excitation signal and the sensing signal; in the monitoring mode, it generates a reference signal for demodulation based on the phase difference and sends it to the acquisition circuit 40, and obtains the detection result of the metal shavings by analyzing the output signal of the analog-to-digital converter circuit 50. The first input terminal of the routing circuit 30 is connected to the first output terminal of the routing circuit 30, and the second input terminal of the routing circuit 30 is connected to the second output terminal of the routing circuit 30.

[0031] Specifically, the lubricating oil metal shavings sensor 10 can detect metal shavings in lubricating oil. Specific manufacturers and models can be selected according to actual needs, and the solutions in this application can be adapted accordingly. Figure 3 The diagram illustrates the structure of a commonly used lubricating oil metal shavings sensor 10, which outputs a sensing signal through its induction coil. (See reference...) Figure 4 The graph shows the characteristics of the lubricating oil metal shavings sensing signal. The horizontal axis represents time, and the vertical axis represents the signal amplitude. It can be seen that when no metal shavings pass through, the sensing signal is a sine wave, and its envelope is a DC signal. When metal shavings pass through, the amplitude of the sensing signal fluctuates, and therefore its envelope also changes. By analyzing the envelope of the sensing signal, the metal shavings can be detected.

[0032] The lubricating oil metal shavings monitoring device consists of a lubricating oil metal shavings sensor 10, a connecting cable, and a demodulator, for example... Figure 2 In this example, the demodulator specifically includes an excitation circuit 20, a routing circuit 30, an analog-to-digital conversion circuit 50, and a processing circuit 60. Of course, in other specific embodiments, the demodulator may also include other functional structures, such as... Figure 3 There is also a calibration circuit, which can be set according to actual needs, and will be explained in detail in the implementation method below.

[0033] The excitation circuit 20 is used to apply an excitation signal to the lubricating oil metal shavings sensor 10 under the control of the processing circuit 60. In other words, whether or not an excitation signal needs to be applied can be controlled by the processing circuit 60. In this application, the excitation circuit 20 is required to apply an excitation signal in both the adaptation mode and the monitoring mode. However, in some cases of the simulation calibration mode and some cases of the self-test mode described later, the excitation circuit 20 is not required to apply an excitation signal, as can be seen in the detailed description of the implementation method below. In short, whether or not the excitation circuit 20 needs to apply an excitation signal can be controlled by the processing circuit 60 to meet the current practical needs.

[0034] The specific circuit structure of the excitation circuit 20 can be set and adjusted according to actual needs. For example, in one specific embodiment of the present invention, see [reference needed]. Figure 5 The diagram below shows the structure of the excitation circuit 20. In this embodiment, the excitation circuit 20 includes: a fifteenth resistor R15, a sixteenth resistor R16, a seventeenth resistor R17, an eighteenth resistor R18, a fifth operational amplifier OP5, and a first switching transistor Q1.

[0035] The first terminal of the fifteenth resistor R15 serves as the control terminal of the excitation circuit 20, connecting to the processing circuit 60. The second terminal of the fifteenth resistor R15 is connected to the non-inverting input terminal of the fifth operational amplifier OP5 and the first terminal of the sixteenth resistor R16. The inverting input terminal of the fifth operational amplifier OP5 is connected to a preset reference voltage. Figure 5 The reference voltage is denoted as Vref, and its specific value can be set according to actual needs. The output terminal of the fifth operational amplifier OP5 is connected to the second terminal of the sixteenth resistor R16 and the control terminal of the first switching transistor Q1, respectively. The first switching transistor... Figure 5 In this example, a MOSFET is used, with its gate serving as the control terminal.

[0036] The second terminal of the first switching transistor Q1 is connected to the negative terminal of the first power supply. Figure 5 The negative terminal of the first power supply is denoted as VSS. The first terminal of the first switching transistor Q1 is connected to the second terminal of the seventeenth resistor R17, which serves as the negative output terminal of the excitation circuit 20. The second terminal of the eighteenth resistor R18 is connected to the positive terminal of the first power supply. Figure 5 The positive terminal of the first power supply is denoted as VCC. The first terminal of the eighteenth resistor R18 serves as the positive output terminal of the excitation circuit 20.

[0037] In this embodiment, the first terminal of the fifteenth resistor R15 serves as the control terminal of the excitation circuit 20, connected to the processing circuit 60. For example, the processing circuit 60 specifically outputs a square wave signal of 0~3.3V. The fifteenth resistor R15, the sixteenth resistor R16, and the fifth operational amplifier OP5 can form a hysteresis comparator circuit, converting the input 0~3.3V signal into a signal with an amplitude of VSS~VCC, used to drive the first switching transistor Q1. Because a hysteresis comparator circuit is formed, input signal interference can be effectively filtered out, thereby improving stability. Furthermore, in this embodiment, the fifth operational amplifier OP5 is used to drive the MOSFET; that is, a comparator is used to implement the MOSFET driving circuit, thus simplifying the MOSFET driving circuit and improving the reliability of the excitation circuit 20.

[0038] The processing circuit 60 uses a square wave signal to drive and control the excitation circuit 20. The frequency of the square wave signal is the same as the frequency of the excitation signal. Since the excitation circuit 20 is connected to the lubricating oil metal shavings sensor 10, the coil and capacitor in the lubricating oil metal shavings sensor 10 form an LC resonant system. This makes the signal in the connecting cable between the excitation circuit 20 and the lubricating oil metal shavings sensor 10 a sinusoidal signal. That is, the excitation signal applied by the excitation circuit 20 to the lubricating oil metal shavings sensor 10 and the induction signal fed back by the induction coil of the lubricating oil metal shavings sensor 10 are both sinusoidal signals. For example, in a specific case, the induction signal is a sinusoidal signal with the same frequency as the excitation signal and an amplitude of ±100mV.

[0039] The routing circuit 30 serves as a signal routing circuit. The first input terminal of the routing circuit 30 is connected to the first output terminal of the routing circuit 30, which is referred to as the first transmission channel of the routing circuit 30 in this application. The second input terminal of the routing circuit 30 is connected to the second output terminal of the routing circuit 30, which is referred to as the second transmission channel of the routing circuit 30 in this application.

[0040] The first transmission channel of the routing circuit 30 is connected to the ADC, i.e., OUT_1 is connected to the analog-to-digital converter circuit 50. The second transmission channel of the routing circuit 30 is connected to the acquisition circuit 40, and then to the analog-to-digital converter circuit 50, i.e., OUT_2 is connected to the acquisition circuit 40. In other words, the signal OUT_1 output from the first transmission channel of the routing circuit 30 directly reaches the analog-to-digital converter circuit 50, while the signal OUT_2 output from the second transmission channel of the routing circuit 30 needs to pass through the acquisition circuit 40 to reach the analog-to-digital converter circuit 50. The following explains the adaptation mode. In adaptation mode, the acquisition circuit 40 is not used; that is, only OUT_1 output from the first transmission channel of the routing circuit 30 is used.

[0041] Specifically, in the adaptation mode, an excitation signal needs to be applied through the excitation circuit 20, and then the sensing signal from the lubricating oil metal shavings sensor 10 is transmitted to the processing circuit 60 through the first transmission channel of the routing circuit 30, the routing circuit 30 and the analog-to-digital conversion circuit 50, and the processing circuit 60 can determine the phase difference between the excitation signal and the sensing signal accordingly.

[0042] See also Figure 6 This is a schematic diagram of the connection structure of the acquisition circuit 40, the routing circuit 30, and the processing circuit 60 in one specific embodiment. In this example, in the adaptation mode, the sensing signal of the lubricating oil metal shavings sensor 10 reaches the routing circuit 30 through the first input terminal IN_1, and is output through the first output terminal OUT_1 of the routing circuit 30, that is... Figure 6 Signal A5 is shown in the image. Figure 6 The analog-to-digital conversion circuit 50 is specifically a 1MHz ADC. After the signal A5 is converted from analog to digital by this ADC, it can be sent to the processing circuit 60, that is, specifically sent to... Figure 6 FPGA in the middle.

[0043] The processing circuit 60 of this application needs to control each circuit module and perform related data parsing and calculation. In practical applications, this can be achieved using an FPGA+CPU structure. For example, in one specific scenario, the FPGA provides control signals for each circuit module, while the CPU provides the control logic and handles tasks such as processing particle signal types. Of course, in other specific embodiments, the processing circuit 60 can adopt other structures, as long as they can effectively fulfill the functional requirements of the processing circuit 60 of this application, without affecting the implementation of the present invention.

[0044] Once the phase difference between the excitation signal and the induced signal is obtained, a suitable reference signal for demodulation can be generated, for example... Figure 6In a specific implementation, the reference signal includes an in-phase reference signal I and a quadrature reference signal Q. The in-phase reference signal I should be in phase and frequency with the induced signal, while I and Q should be 90° out of phase. Therefore, it is understandable that if the excitation signal is directly used as the in-phase reference signal I instead of being adapted according to the scheme of this application, a phase difference will exist between the in-phase reference signal I and the induced signal, resulting in ineffective synchronous demodulation. Furthermore, the value of this phase difference may differ for lubricating oil metal chip sensors 10 from different manufacturers and models. In this application, the phase difference can be obtained in the adaptation mode. For example, in one specific embodiment, in the adaptation mode, if the phase difference between the excitation signal and the sensing signal is determined to be 30°, then the in-phase component reference signal I and the quadrature component reference signal Q before adjustment can be obtained based on the excitation signal. Then, both the in-phase component reference signal I and the quadrature component reference signal Q are delayed by 30° to obtain the adjusted in-phase component reference signal I and the quadrature component reference signal Q required by the lubricating oil metal shavings sensor 10. At this time, the in-phase component reference signal I is in phase and frequency with the sensing signal generated by the lubricating oil metal shavings sensor 10, which can effectively achieve synchronous demodulation.

[0045] Furthermore, it is understood that for a specific model of lubricating oil metal shavings sensor 10, the aforementioned phase difference is fixed. Therefore, in practical applications, when a lubricating oil metal shavings sensor 10 is first connected to the demodulator, it needs to enter the adaptation mode to complete the calculation of the aforementioned phase difference. In subsequent use of the lubricating oil metal shavings monitoring device, no further adaptation is required. In other words, in subsequent normal operation, the phase shift of the reference signal can be performed according to the phase difference obtained in the adaptation mode.

[0046] In monitoring mode, the acquisition circuit 40 can effectively demodulate based on the adjusted reference signal and send the result to the analog-to-digital converter circuit 50. The processing circuit 60 can then analyze the output signal of the analog-to-digital converter circuit 50 to obtain the detection result of the metal shavings. The specific structure of the acquisition circuit 40 can be set and adjusted according to actual needs, as long as it can meet the functional requirements of the present application. For example, in one specific embodiment of the present invention, the acquisition circuit 40 may include: The preamplifier circuit INA is used to initially amplify the received induced signal. A demodulation circuit connected to the preamplifier circuit INA is used to demodulate the output signal of the preamplifier circuit INA based on a reference signal. The output signal of the demodulation circuit is connected to the analog-to-digital converter circuit 50 and the high-pass filter amplifier circuit, respectively. This allows the processing circuit 60 to detect metal shavings based on the output signal of the demodulation circuit when the sensed signal is a large particle signal, and to detect metal shavings based on the output signal of the high-pass filter amplifier circuit when the sensed signal is a small particle signal. A high-pass filter amplifier circuit used for high-pass filtering and amplification of the output signal of the demodulation circuit; Among them, when the amplitude of the particle signal in the sensing signal reaches the preset first threshold, the sensing signal belongs to the large particle signal; when the amplitude of the particle signal in the sensing signal is not greater than the first threshold, the sensing signal belongs to the small particle signal.

[0047] In this embodiment, the preamplifier circuit INA can initially amplify the received induced signal. The specific structure of the preamplifier circuit INA can be set as needed, for example... Figure 7 The structure of the preamplifier circuit INA in one specific embodiment is a preamplifier circuit implemented using an instrumentation amplifier. It has a simple structure, is easy to implement, and has high reliability. Figure 7 The INA_OUT shown in the diagram represents the output terminal of the preamplifier circuit INA. Figure 7 The left side is the positive / negative input terminal of the preamplifier circuit INA, which is specifically connected to the second transmission channel OUT_2 of the routing circuit 30, that is, connected to the positive and negative terminals of the second output terminal OUT_2 of the routing circuit 30 respectively.

[0048] It should be noted that the typical sensitivity specifications of the lubricating oil metal shavings sensor 10 are as follows: the sensing signal is a sinusoidal signal with the same frequency as the excitation signal, ranging from ±100mV. The range of Fe particle signals is 100μm to 500μm, which is reflected in the sensing signal as 20μV to 5000μV. The range of nFe particle signals is 300μm to 900μm, which is reflected in the sensing signal as 50μV to 500μV. Therefore, according to the working principle, the particle signal is modulated onto the sensing signal with a modulation depth of 20μV / (200mV). 1000)~5000μV / (200mV) (1000), or 0.01‰ to 25‰, shows that for small particle signals, the reflected value in the induced signal is too weak to be directly digitally demodulated. In other words, a fully digital demodulation scheme is only suitable for larger particle signals. Furthermore, since the induced signal is a ±100mV carrier signal, it cannot be amplified excessively, otherwise it will exceed the operating range of the relevant operational amplifier in the demodulator or the sampling range of the ADC. For example, if the induced signal is amplified 3000 times through the acquisition circuit 40, the smallest particle signal of 20μV will only be 60mV when acquired by the ADC, and the largest particle signal of 5000μV will be amplified to 15000mV. This causes the amplified small particle signal to be submerged in background noise, while the large particle signal exceeds the typical ADC operating range (±10V).

[0049] To address this issue, this implementation method employs different processing approaches for cases with weak (small particle signals) and strong (large particle signals).

[0050] Specifically, when the amplitude of the particle signal in the induced signal reaches a preset first threshold, the induced signal is considered a large particle signal; when the amplitude of the particle signal in the induced signal is not greater than the first threshold, the induced signal is considered a small particle signal. For example, in one scenario, 300uV is used as the dividing line. That is, when the amplitude of the particle signal in the induced signal reaches 300uV, the induced signal is considered a large particle signal and is therefore processed using the large particle processing method; conversely, when it is less than 300uV, it is a small particle signal and is processed using the small particle processing method. In practical applications, the processing circuit 60 can easily and quickly determine whether the induced signal belongs to a large particle signal or a small particle signal through the various outputs of the ADC.

[0051] First, we will explain the case of particles with a signal sensitivity of 300μV or higher, i.e., the induced signal belongs to the category of large particle signals. Because it is a large particle signal, in this embodiment, the induced signal is transmitted to the ADC after passing through the pre-amplifier circuit INA and the demodulation circuit. The processing circuit 60 then detects metal scraps based on the output signal of the demodulation circuit. Figure 6 For example, in the case of large-particle signals, the processing circuit 60 essentially utilizes... Figure 6 A1 and A4 in the code enable the detection of metal shavings.

[0052] For particles with a signal sensitivity of less than 300μV, i.e., when the induced signal is a small particle signal, in this embodiment, the induced signal is amplified by a pre-amplifier circuit INA and a demodulation circuit, and then further amplified by a high-pass filter amplifier circuit. This ensures the small particle signal is amplified sufficiently so that the processing circuit 60 detects metal chips based on the output signal of the high-pass filter amplifier circuit. Figure 6 For example, in the case of small particle signals, the processing circuit 60 essentially utilizes... Figure 6 In this context, A2 and A3 are used to detect metal shavings. For example, in a specific scenario, the FPGA is based on A2 and A3 after analog-to-digital conversion. After calculating the square root of the signals of the two, the CPU then determines the particles.

[0053] As can be seen, in this implementation, small particle signals need to be processed by a demodulation circuit and a high-pass filter amplification circuit to achieve sufficient amplification, so that the processing circuit 60 can effectively detect metal shavings. For large particle signals, only the demodulation circuit is needed, so large particle signals are less likely to exceed the ADC's operating range.

[0054] The specific structures of the demodulation circuit and the high-pass filter amplifier circuit can be set and adjusted according to actual needs. For example, in one specific embodiment of the present invention, the demodulation circuit is a dual-channel demodulation circuit, and more details can be found in [reference needed]. Figure 6 The demodulation circuit specifically includes: The input terminal is connected to the output terminal of the preamplifier circuit INA, and is used to amplify the input signal by a factor of K in the first amplifier circuit 401; where K represents the amplification factor, for example, in a specific case, K is set to 2.

[0055] The input terminal is connected to the output terminal of the preamplifier circuit INA, and is used by the second amplifier circuit 402 to amplify the input signal by -K times; A first switching circuit 403 has its input terminal connected to the output terminal of the first amplifier circuit 401 and its output terminal connected to the input terminal of the first low-pass filter circuit 405. The control terminal of the first switching circuit 403 is used to receive the in-phase component reference signal in the reference signal, so as to control the on / off state of the first switching circuit 403 through the in-phase component reference signal. The input terminal is connected to the output terminal of the second amplifier circuit 402, and the output terminal is connected to the input terminal of the second low-pass filter circuit 406. The control terminal of the second switch circuit 404 is used to receive the quadrature component reference signal in the reference signal, so as to control the on / off state of the second switch circuit 404 through the quadrature component reference signal. A first low-pass filter circuit 405 whose input terminal is connected to the output terminal of the first switching circuit 403; The input terminal is connected to the output terminal of the second switching circuit 404, which is a second low-pass filter circuit 406.

[0056] In this embodiment, taking K=2 as an example, the output signal of the preamplifier circuit INA is amplified by a factor of 2 by the first amplifier circuit 401, and the output signal of the preamplifier circuit INA is amplified by a factor of -2 by the second amplifier circuit 402. The specific structures of the first amplifier circuit 401 and the second amplifier circuit 402 can be set and adjusted according to actual needs. For example, in a specific embodiment of the present invention, see [reference needed]. Figure 8 The first amplifier circuit 401 includes: a first operational amplifier OP1, a first resistor R1 and a second resistor R2; the second amplifier circuit 402 includes: a second operational amplifier OP2, a third resistor R3 and a fourth resistor R4. The non-inverting input of the first operational amplifier OP1 is used as the input of the first amplifier circuit 401 to connect to the output of the preamplifier circuit INA. The inverting input of the first operational amplifier OP1 is connected to the second end of the first resistor R1 and the first end of the second resistor R2 respectively. The first end of the first resistor R1 is grounded. The second end of the second resistor R2 is connected to the output of the first operational amplifier OP1 and the connection end is used as the output of the first amplifier circuit 401. The first end of the third resistor R3 serves as the input terminal of the second amplifier circuit 402 and is connected to the output terminal of the preamplifier circuit INA. The second end of the third resistor R3 is connected to the inverting input terminal of the second operational amplifier OP2 and the first end of the fourth resistor R4. The non-inverting input terminal of the second operational amplifier OP2 is grounded. The output terminal of the second operational amplifier OP2 is connected to the second end of the fourth resistor R4, and the connection terminal serves as the output terminal of the second amplifier circuit 402.

[0057] Figure 8 In this implementation method, 2x amplification is achieved by using co-directional amplification and -2x amplification is achieved by using reverse amplification. The structure is simple and easy to implement.

[0058] The input terminal of the first switching circuit 403 is connected to the output terminal of the first amplifier circuit 401. The on / off state of the first switching circuit 403 is controlled by the in-phase component reference signal I. The first low-pass filter circuit 405 is connected to the output terminal of the first switching circuit 403. The input terminal of the second switching circuit 404 is connected to the output terminal of the second amplifier circuit 402. The on / off state of the second switching circuit 404 is controlled by the quadrature component reference signal Q. The second low-pass filter circuit 406 is connected to the output terminal of the second switching circuit 404.

[0059] Figure 6The output signals of the first low-pass filter circuit 405 and the second low-pass filter circuit 406 are denoted as A1 and A4, respectively. These are signals that have been demodulated. As described above, for large particles, after signals A1 and A4 are transmitted to the processing circuit 60 through the ADC, the processing circuit 60 can detect the metal shavings accordingly.

[0060] The specific structures of the first low-pass filter circuit 405 and the second low-pass filter circuit 406 can be set and adjusted according to actual needs. For example, in one specific embodiment of the present invention, see [reference needed]. Figure 9 The first low-pass filter circuit 405 includes: a third operational amplifier OP3, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a first capacitor C1, a second capacitor C2, and a third capacitor C3.

[0061] The first terminal of the fifth resistor R5 serves as the input terminal of the first low-pass filter circuit 405. The second terminal of the fifth resistor R5 is connected to the first terminal of the first capacitor C1 and the first terminal of the sixth resistor R6. The second terminal of the sixth resistor R6 is connected to the first terminal of the seventh resistor R7 and the first terminal of the second capacitor C2. The second terminal of the seventh resistor R7 is connected to the first terminal of the third capacitor C3 and the non-inverting input terminal of the third operational amplifier OP3. The second terminal of the first capacitor C1 is grounded, and the second terminal of the third capacitor C3 is grounded. The inverting input terminal of the third operational amplifier OP3 is connected to the first terminal of the eighth resistor R8 and the first terminal of the ninth resistor R9, respectively. The second terminal of the eighth resistor R8 is grounded. The output terminal of the third operational amplifier OP3 is connected to the second terminal of the ninth resistor R9 and the second terminal of the second capacitor C2, and the connection terminal serves as the output terminal of the first low-pass filter circuit 405.

[0062] Figure 9 The left side is the input terminal of the first low-pass filter circuit 405, and the right side is the output terminal of the first low-pass filter circuit 405. Using a third-order active filter circuit can effectively filter out the 107kHz carrier signal in the induced signal (the resonant frequency of the lubricating oil metal shavings sensor 10 is typically 107kHz). Furthermore, in this embodiment, a single operational amplifier is used to implement the third-order low-pass filter, ensuring both filtering effectiveness and reducing circuit complexity. Compared to some solutions that use a single operational amplifier to implement second-order filtering or dual operational amplifiers to implement fourth-order filtering, the insufficient attenuation of a second-order filter can lead to incomplete filtering of the 107kHz signal, while the circuit complexity of a fourth-order filter is too high.

[0063] Furthermore, it is understandable that, for the sake of design simplification, the structures of the first low-pass filter circuit 405 and the second low-pass filter circuit 406 can often be the same; that is, the second low-pass filter circuit 406 can also be... Figure 9The design.

[0064] If a dual-channel demodulation circuit is selected as the demodulation circuit, then a dual-channel high-pass filter amplifier circuit can also be selected, and the specific structure can be set according to actual needs. For example, in one specific embodiment of the present invention, see [reference needed]. Figure 6 The high-pass filter amplifier circuit specifically includes: The input terminal is connected to the output terminal of the first low-pass filter circuit 405; the first high-pass filter circuit 407 is connected to the input terminal of the first low-pass filter circuit 405. The input terminal is connected to the output terminal of the first high-pass filter circuit 407, and the output terminal is connected to the third amplifier circuit 409, which is connected to the analog-to-digital converter circuit 50. A second high-pass filter circuit 408 whose input terminal is connected to the output terminal of the second low-pass filter circuit 406; The input terminal is connected to the output terminal of the second high-pass filter circuit 408, and the output terminal is connected to the fourth amplifier circuit 410, which is connected to the analog-to-digital converter circuit 50.

[0065] In this embodiment, high-pass filtering is effectively achieved through the first high-pass filter circuit 407 and the second high-pass filter circuit 408, while the signal can be further amplified through the third amplifier circuit 409 and the fourth amplifier circuit 410, which is suitable for small particle signals. Of course, the specific structures of the first high-pass filter circuit 407, the second high-pass filter circuit 408, the third amplifier circuit 409, and the fourth amplifier circuit 410 can be set and adjusted according to actual needs. For example, in one case, the third amplifier circuit 409 and the fourth amplifier circuit 410 can both adopt the structure of the first amplifier circuit 401 mentioned above. Of course, the models of the corresponding components can be adjusted as needed to achieve the required amplification factor. For example, in one case, the third amplifier circuit 409 and the fourth amplifier circuit 410 can both amplify the signal by 20 times.

[0066] Figure 6 The output signals of the third amplifier circuit 409 and the fourth amplifier circuit 410 are denoted as A2 and A3, respectively. As described above, for small particles, after signals A2 and A3 are transmitted to the processing circuit 60 through the ADC, the processing circuit 60 can detect the metal shavings.

[0067] In one specific embodiment of the present invention, see [reference needed]. Figure 10 The first high-pass filter circuit 407 includes a fourth operational amplifier OP4, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14, a fourth capacitor C4, a fifth capacitor C5, and a sixth capacitor C6.

[0068] The first terminal of the fourth capacitor C4 serves as the input terminal of the first high-pass filter circuit 407. The second terminal of the fourth capacitor C4 is connected to the first terminal of the fifth capacitor C5 and the first terminal of the tenth resistor R10. The second terminal of the tenth resistor R10 is grounded. The second terminal of the fifth capacitor C5 is connected to the first terminal of the sixth capacitor C6 and the first terminal of the eleventh resistor R11. The second terminal of the sixth capacitor C6 is connected to the first terminal of the twelfth resistor R12 and the non-inverting input terminal of the fourth operational amplifier OP4. The second terminal of the twelfth resistor R12 is grounded. The inverting input terminal of the fourth operational amplifier OP4 is connected to the first terminal of the thirteenth resistor R13 and the first terminal of the fourteenth resistor R14, respectively. The second terminal of the thirteenth resistor R13 is grounded. The output terminal of the fourth operational amplifier OP4 is connected to the second terminal of the fourteenth resistor R14 and the second terminal of the eleventh resistor R11, and the connection terminal serves as the output terminal of the first high-pass filter circuit 407.

[0069] Figure 10 In this implementation, the left side is the input terminal of the first high-pass filter circuit 407, and the right side is the output terminal of the first high-pass filter circuit 407. Considering that low-frequency 1 / f noise affects the sampling accuracy of subsequent stages, and that the DC bias signal affects the AC amplitude range of subsequent sampling stages, this implementation uses a third-order active high-pass filter structure as the first high-pass filter circuit 407, which can effectively filter out low-frequency signals. Furthermore, in this implementation, a single operational amplifier is used to implement the third-order high-pass filter, ensuring both filtering effectiveness and reducing circuit complexity. Compared to some solutions that use a single operational amplifier to implement second-order filtering or dual operational amplifiers to implement fourth-order filtering, the third-order high-pass filter in this implementation ensures filtering effectiveness without excessive circuit complexity.

[0070] Furthermore, it is understandable that, for the sake of design simplification, the structures of the first high-pass filter circuit 407 and the second high-pass filter circuit 408 can often be the same; that is, the second high-pass filter circuit 408 can also be adopted. Figure 10 The design.

[0071] In one specific embodiment of the present invention, the demodulation circuit can be a single-channel demodulation circuit, and demodulation is performed based on the in-phase component reference signal and the quadrature component reference signal in the reference signal by time-division multiplexing.

[0072] The above text elaborates on the fact that the demodulation circuit is a dual-channel demodulation circuit. Figure 6For example, the first amplifier circuit 401, the first switch circuit 403, and the first low-pass filter circuit 405 constitute one channel of the demodulation circuit. Correspondingly, the second amplifier circuit 402, the second switch circuit 404, and the second low-pass filter circuit 406 constitute the other channel of the demodulation circuit. If a single-channel demodulation circuit is used, only one channel needs to be set. For example, only the first amplifier circuit 401, the first switch circuit 403, and the first low-pass filter circuit 405 need to be set, without the need for the second amplifier circuit 402, the second switch circuit 404, and the second low-pass filter circuit 406. In this case, demodulation is required based on the in-phase component reference signal and the quadrature component reference signal in the reference signal through time-division multiplexing. That is, the first switch circuit 403 receives the in-phase component reference signal I and the quadrature component reference signal Q through time-division multiplexing. The advantage of this implementation is that it can reduce the number of components and the board area, saving costs.

[0073] Furthermore, it is understandable that if the demodulation circuit adopts a single-channel demodulation circuit implementation, then the high-pass filter amplifier circuit also only needs to be set to a single channel, still based on... Figure 6 For example, a single-channel high-pass filter amplifier circuit consists of a first high-pass filter circuit 407 and a third amplifier circuit 409, and does not require a second high-pass filter circuit 408 and a fourth amplifier circuit 410.

[0074] In one specific embodiment of the present invention, see [reference needed]. Figure 11 A fifth amplifier circuit 31 is also provided between the first input terminal and the first output terminal of the routing circuit 30.

[0075] The first output terminal of the routing circuit 30 is OUT_1, and the signal output by this channel is... Figure 6 The term A5 is used in this implementation. As described above, in the adaptation mode, A5 is used to calculate the phase difference. This implementation also takes into account that an amplifier, called the fifth amplifier circuit 31, can be set between the first input terminal and the first output terminal of the routing circuit 30. That is, the fifth amplifier circuit 31 is set on the first transmission channel of the routing circuit 30 so that the output of OUT_1 has sufficient amplitude, which can facilitate the use of A5.

[0076] Furthermore, in some implementations, the signal A5 output from the first output terminal OUT_1 of the routing circuit 30 can also be used for processing large particle signals. That is, for large particle signals, the processing circuit 60 can detect metal debris based on A1 and A4, or it can directly use A5 to detect metal debris. For example, in one scenario, after A5 is converted by an ADC, absolute demodulation is performed in the FPGA using an ABS+low-pass filter to obtain the amplitude of the original signal. The phase compensation between the reference signal and the induced signal can be calculated quickly and easily. Then, a high-pass filter is applied to identify the particle signal when large particles cause amplitude limiting in the analog channel. In another scenario, after A5 is converted by an ADC, quadrature demodulation is performed in the FPGA to calculate the phase shift between the induced signal and the reference signal. Then, based on the quadrature demodulation result, metal debris analysis and detection are performed.

[0077] In one specific embodiment of the present invention, it may further include: A digital-to-analog converter J1 connected to the processing circuit 60, used to receive the simulation signal output by the processing circuit 60 and output it to the third input terminal of the routing circuit 30 after digital-to-analog conversion; The routing circuit 30 also includes a switch 32. The first terminal of the switch 32 serves as the second input terminal of the routing circuit 30, the second terminal serves as the third input terminal, and the third terminal serves as the second output terminal. In monitoring mode, the switch 32 is in its first state, connecting the second input terminal and the second output terminal of the routing circuit 30. In simulation calibration mode, the switch 32 is in its second state, connecting the third input terminal and the second output terminal of the routing circuit 30.

[0078] The processing circuit 60 is also used to: send a first simulation signal to the third input terminal of the routing circuit 30 for software calibration in simulation calibration mode; send a second simulation signal to the third input terminal of the routing circuit 30 for calibration of the low-pass filter circuit structure in the acquisition circuit 40 in simulation calibration mode; and send a third simulation signal to the third input terminal of the routing circuit 30 for calibration of the high-pass filter circuit structure in the acquisition circuit 40 in simulation calibration mode.

[0079] See also Figure 12 In this implementation, it is also possible to generate simulation signals to achieve hardware and software calibration.

[0080] Specifically, the simulation signal output by the processing circuit 60 can be sent to the digital-to-analog converter J1 in the calibration circuit, that is... Figure 12 The DAC in this implementation can be found in [reference needed]. Figure 11The routing circuit 30 also includes a switch 32. The first terminal of switch 32 serves as the second input terminal IN_2 of the routing circuit 30, the second terminal serves as the third input terminal IN_3, and the third terminal serves as the second output terminal OUT_2. It can be seen that by controlling the switch, it is possible to determine whether the signal output by OUT_2 of the routing circuit 30 originates from IN_2 or IN_3.

[0081] In monitoring mode, switch 32 is in the first state, so that the second input terminal of routing circuit 30 is connected to the second output terminal of routing circuit 30, that is, OUT_2 and IN_2 are connected. At this time, the sensing signal generated by the lubricating oil metal shavings sensor 10 when it is working normally can enter the routing circuit 30 through IN_2 and be output through OUT_2 of routing circuit 30, that is, reach the acquisition circuit 40 through the second transmission channel of routing circuit 30.

[0082] In simulation calibration mode, switch 32 is in its second state, connecting the third input terminal of routing circuit 30 to its second output terminal, i.e., connecting OUT_2 and IN_3. For ease of description, the transmission channel formed by OUT_2 and IN_3 is referred to as the third transmission channel of routing circuit 30. In other words, in simulation calibration mode, the simulation signal is output using the third transmission channel of routing circuit 30.

[0083] Furthermore, in this implementation, there are multiple simulation signals, which respectively realize different simulation functions. Specifically, this implementation includes a first simulation signal, a second simulation signal, and a third simulation signal, which are used for software calibration, calibration of the low-pass filter circuit structure, and calibration of the high-pass filter circuit structure, respectively.

[0084] To achieve software calibration, the first simulated signal should mimic the actual inductive signal. For example, in one specific implementation, see [reference needed]. Figure 12 The first simulation signal is specifically: the induced signal simulated by superimposing the particle signal output by the particle signal generator of the processing circuit 60 and the carrier signal output by the frequency synthesizer of the processing circuit 60.

[0085] exist Figure 12 In this implementation, the processing circuit 60 outputs a particle signal through a particle signal generator and a carrier signal through a frequency synthesizer (DDS). Both can be multiplied by a multiplier in the processing circuit 60. Figure 12The signal is superimposed (denoted as J2) to form the simulated induction signal, which is also the first simulated signal. The waveform of the first simulated signal is consistent with the waveform of the induction signal generated when the particles pass through the lubricating oil metal shavings sensor 10. Therefore, the waveform of the first simulated signal can also be referred to Figure 4 Using the first simulated signal, relevant calibrations can be effectively performed in the software.

[0086] Particle signals can distinguish between ferromagnetic and non-ferromagnetic particles; see reference [link / reference needed]. Figure 14 The image shows the particle signal characteristics of Fe and nFe generated by the particle signal generator, where Fe represents ferromagnetic chips and nFe represents non-ferromagnetic chips. The specific amplitude and duration can be set and adjusted according to actual needs, such as the flow rate of lubricating oil in the lubricating oil metal chip sensor 10 in actual applications.

[0087] Furthermore, it is understandable that since the first simulated signal should mimic the real inductive signal, simulation can also be achieved by directly using the inductive signal instead of the first simulated signal, thus enabling related software calibration. However, this would require real metal particles to pass through the lubricating oil metal shavings sensor 10, making the operation more complex. Moreover, when real metal particles pass through, the particle signal is not particularly controllable. This implementation method, however, utilizes the first simulated signal constructed entirely by the processing circuit 60. That is, both the particle signal output by the particle signal generator and the carrier signal output by the DDS are fully controllable, thus effectively ensuring the simulation effect.

[0088] Furthermore, in one specific implementation of this part, see [reference needed]. Figure 12 It may also include: The first input terminal is connected to the output terminal of the lubricating oil metal shavings sensor 10, the second input terminal is connected to the output terminal of the digital-to-analog converter circuit J1, and the output terminal is connected to the first input terminal of the routing circuit 30, which is used for signal superposition multiplier J6.

[0089] The processing circuit 60 is also used to: in simulation calibration mode, output a particle signal through a particle signal generator, and use the particle signal output by the particle signal generator to superimpose the sensing signal output by the lubricating oil metal shavings sensor 10 when no metal shavings are generated to obtain a fourth simulation signal for software calibration.

[0090] In this embodiment, the particle signal can still be output by the particle signal generator, and the sensing signal output by the lubricating oil metal shavings sensor 10 when no metal shavings are generated can be used as a carrier signal, thereby superimposing it with the particle signal output by the particle signal generator. The resulting fourth simulation signal for software calibration is equivalent to the first simulation signal in the above embodiment, only from a different source. It can be seen that the first simulation signal originates entirely from the processing circuit 60, while the fourth simulation signal is generated by superimposing the particle signal output by the processing circuit 60 with the sensing signal output by the lubricating oil metal shavings sensor 10 when no metal shavings are generated. Therefore, this embodiment improves the simulation flexibility of the present application's solution.

[0091] See also Figure 12 ,exist Figure 12 In this implementation, a switch J5 is also provided after the multiplier J2 in the processing circuit 60. When the first simulation signal implementation is used, the input terminal of the switch J5 is connected to the multiplier J2. When the fourth simulation signal implementation is used, the input terminal of the switch J5 is connected to the particle signal generator. Of course, the switch J5 can also be omitted, because even if the fourth simulation signal implementation is used, as long as the DDS is controlled not to output a signal, the signal output by the multiplier at this time is the particle signal output by the particle signal generator.

[0092] also, Figure 12 In the calibration circuit, after the DAC, there is a low-pass filter J3 for low-pass filtering and a follower J4 for ensuring signal stability.

[0093] Similar to the first simulated signal, the second and third simulated signals can also be generated by the processing circuit 60. For example, when calibrating the low-pass filter circuit structure in the acquisition circuit 40, the inductive signal when no particles pass through is usually used. That is to say, the second simulated signal generated by the processing circuit 60 should simulate the inductive signal when no particles pass through. The waveform of the second simulated signal can be found in [reference needed]. Figure 15 When calibrating the high-pass filter circuit structure in the acquisition circuit 40, an inductive signal with a sinusoidal envelope is typically used. In other words, the third simulated signal generated by the processing circuit 60 should simulate an inductive signal with a sinusoidal envelope. The waveform of the third simulated signal can be found in [reference needed]. Figure 16 .

[0094] In one specific embodiment of the present invention, the routing circuit 30 is further provided with a fourth input terminal and a third output terminal, and the fourth input terminal of the routing circuit 30 is connected to the third output terminal of the routing circuit 30. The third output terminal of the routing circuit 30 is connected to the analog-to-digital converter circuit 50, so that the output signal of the third output terminal of the routing circuit 30 is sent to the processing circuit 60 through the analog-to-digital converter circuit 50; the fourth input terminal of the routing circuit 30 is connected to the excitation circuit 20. The processing circuit 60 is also used in self-test mode to apply an excitation signal through the excitation circuit 20 when the excitation circuit self-test is performed, and to obtain the signal output by the third output terminal of the routing circuit 30 through the analog-to-digital converter circuit 50. When the signal output by the third output terminal of the routing circuit 30 is abnormal, the excitation circuit self-test is determined to be abnormal. In self-test mode, when the sensing circuit self-test is performed, an excitation signal is applied through the excitation circuit 20 to control the self-test line of the sensing circuit to be turned on, so that the excitation signal is applied to the output terminal of the lubricating oil metal shavings sensor 10 through the self-test line of the sensing circuit, and the signal output by the first output terminal of the routing circuit 30 is obtained through the analog-to-digital conversion circuit 50. When the signal output by the first output terminal of the routing circuit 30 is abnormal, it is determined that the self-test of the sensing circuit is abnormal. The induction circuit self-test line is connected between the output terminal of the excitation circuit 20 and the output terminal of the lubricating oil metal shavings sensor 10, and is in an open circuit state by default, only in a conducting state during the induction circuit self-test.

[0095] In this embodiment, self-testing of the lubricating oil metal shavings monitoring device is also supported. This is because when the lubricating oil metal shavings monitoring device is abnormal, it may be due to a problem with the sensing circuit or the excitation circuit. In this embodiment, self-testing of the excitation circuit and the sensing circuit can be performed separately, thereby enabling faster fault location.

[0096] Specifically, in this implementation method, please refer to... Figure 11 The routing circuit 30 also needs to be equipped with a fourth input terminal IN_4 and a third output terminal OUT_3. The fourth input terminal and the third output terminal of the routing circuit 30 are connected, which is conveniently referred to as the fourth transmission channel of the routing circuit 30. This fourth transmission channel of the routing circuit 30 is directly connected to the analog-to-digital converter circuit 50. Figure 6 The A6 in the signal allows the processing circuit 60 to perform a self-test based on the signal from that channel.

[0097] See also Figure 13 To achieve self-testing, a self-testing circuit with an induction loop needs to be set up. Figure 13It can be seen that the induction loop self-test circuit is connected between the output terminal of the excitation circuit 20 and the output terminal of the lubricating oil metal shavings sensor 10, effectively bypassing the lubricating oil metal shavings sensor 10. Furthermore, to avoid affecting normal operation, the induction loop self-test circuit is only in a conducting state during the self-test; otherwise, it is in a default open-circuit state. In some embodiments, an additional excitation circuit 20 may be provided specifically to provide an excitation signal for the induction loop self-test circuit.

[0098] During the self-test of the sensing circuit, an excitation signal needs to be applied through the excitation circuit 20, and the self-test circuit of the sensing circuit needs to be turned on. This allows the excitation signal to be applied to the output terminal of the lubricating oil metal shavings sensor 10 through the self-test circuit. It can be understood that if the sensing circuit is normal, the first transmission channel of the routing circuit 30 and the ADC processing circuit 60 can determine that A5 output by OUT_1 is normal, i.e., the self-test of the sensing circuit is normal. Conversely, if the self-test is abnormal, it can be determined that the self-test of the sensing circuit is abnormal.

[0099] For example, in one specific embodiment, by performing time-frequency analysis on A5, when the induction loop self-test is performed, if the signal A5 output by the first output terminal OUT_1 of the routing circuit 30 is a DC signal, the processing circuit 60 can determine that the induction loop self-test is abnormal and the abnormality type is induction loop disconnection, that is, the induction loop cable is broken. If the signal A5 output by the first output terminal OUT_1 of the routing circuit 30 is a square wave signal, the processing circuit 60 can determine that the induction loop self-test is abnormal and the abnormality type is induction loop short circuit, that is, the induction loop cable is short circuit. In other embodiments, time-frequency analysis can also be performed on A5. If it is a sinusoidal signal and the amplitude is within a reasonable range, it indicates that the cable of the induction loop and the induction loop of the lubricating oil metal shavings sensor 10 are normal. If it is a sinusoidal signal and the amplitude exceeds a reasonable range, it indicates that the lubricating oil metal shavings sensor 10 itself may be abnormal.

[0100] When performing a self-test of the excitation circuit, an excitation signal needs to be applied through the excitation circuit 20, and the signal output from the third output terminal OUT_3 of the routing circuit 30 is obtained through the analog-to-digital converter circuit 50. In other words, during the self-test of the excitation circuit, the processing circuit 60 receives the signal through the fourth transmission channel of the routing circuit 30 and the ADC. If the excitation circuit is normal, the processing circuit 60 can determine that the A6 output by OUT_3 is normal, that is, determine that the self-test of the excitation circuit is normal. Otherwise, it can determine that the self-test of the excitation circuit is abnormal.

[0101] For example, in one specific embodiment, by performing time-frequency analysis on A6, when the excitation circuit self-test is performed, if the signal A6 output by the third output terminal OUT_3 of the routing circuit 30 is a DC signal, the processing circuit 60 can determine that the excitation circuit self-test is abnormal and the abnormality type is excitation circuit disconnection, that is, the excitation circuit cable is broken. If the signal A6 output by the third output terminal OUT_3 of the routing circuit 30 is a square wave signal, the processing circuit 60 can determine that the excitation circuit self-test is abnormal and the abnormality type is excitation circuit short circuit, that is, the excitation circuit cable is short circuit. In other embodiments, time-frequency analysis can also be performed on A6. If it is a sinusoidal signal and the amplitude is within a reasonable range, it indicates that the excitation circuit cable and the sensing circuit of the lubricating oil metal shavings sensor 10 are normal. If it is a sinusoidal signal and the amplitude exceeds a reasonable range, it indicates that the lubricating oil metal shavings sensor 10 itself may be abnormal.

[0102] In one specific embodiment of the present invention, an attenuator 33 is further provided between the fourth input terminal IN_4 and the third output terminal OUT_3 of the routing circuit 30. Referring to 11, an attenuator 33 is provided on the fourth transmission channel of the routing circuit 30 to avoid the amplitude of A6 being too large and affecting the accuracy of the self-test. For example, in one specific case, the attenuator 33 performs a 10-fold signal attenuation.

[0103] Applying the technical solution provided in the embodiments of this invention, considering that if demodulation is performed directly using the excitation signal, the phase difference between the excitation signal and the sensing signal will lead to demodulation failure, and this phase difference may be different for different lubricating oil metal shavings sensors 10, this application's solution detects the phase difference in an adaptation mode, thereby achieving compensation. This allows the demodulator of this application's solution to be flexibly adapted to lubricating oil metal shavings sensors 10 from different manufacturers.

[0104] Specifically, in the adaptation mode, an excitation signal is applied through the excitation circuit 20. The sensing signal output by the lubricating oil metal shavings sensor 10 can then be output through the first output terminal of the routing circuit 30 and transmitted to the analog-to-digital converter circuit 50 for analog-to-digital conversion. This signal is then received by the processing circuit 60, which determines the phase difference between the excitation signal and the sensing signal, i.e., the phase offset between them. Based on this phase difference, a reference signal for demodulation is generated. In the monitoring mode, after the reference signal is sent to the acquisition circuit 40, demodulation is effectively achieved. Finally, the processing circuit 60 accurately obtains the detection result of the metal shavings by analyzing the output signal of the analog-to-digital converter circuit 50. In summary, this application's solution determines the phase difference between the excitation signal and the sensing signal through the adaptation mode, thereby generating a reference signal adapted to the current model of the lubricating oil metal shavings sensor 10, which can effectively achieve demodulation, ensuring the flexibility and reliability of this application's solution.

[0105] Corresponding to the embodiments of the lubricating oil metal shavings monitoring device described above, this invention also provides a method for monitoring lubricating oil metal shavings, which can be applied to the processing circuit of the lubricating oil metal shavings monitoring device as described in any of the above embodiments. (See also...) Figure 17 This includes the following steps: Step S101: In the adaptation mode, an excitation signal is applied through the excitation circuit, and the sensing signal from the lubricating oil metal shavings sensor is obtained from the first output terminal of the routing circuit through the analog-to-digital conversion circuit, and the phase difference between the excitation signal and the sensing signal is determined. Step S102: In monitoring mode, a reference signal for demodulation is generated based on the phase difference and sent to the acquisition circuit. The detection result of metal shavings is obtained by analyzing the output signal of the analog-to-digital conversion circuit.

[0106] It should also be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0107] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0108] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the technical solutions and core ideas of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the present invention.

Claims

1. A device for monitoring lubricating oil metal shavings, characterized in that, include: A lubricating oil metal shavings sensor used to detect metal shavings in lubricating oil and output a sensing signal; An excitation circuit for applying an excitation signal to the lubricating oil metal shavings sensor under the control of the processing circuit; Both the first and second input terminals are connected to the output terminal of the lubricating oil metal shavings sensor, forming a routing circuit for signal routing. An analog-to-digital converter circuit connected to the first output terminal of the routing circuit for performing analog-to-digital conversion; The acquisition circuit, whose input terminal is connected to the second output terminal of the routing circuit and whose output terminal is connected to the analog-to-digital conversion circuit, is used to demodulate and amplify the received induced signal based on the reference signal and then output it to the analog-to-digital conversion circuit. The processing circuit is used to apply an excitation signal through the excitation circuit in the adaptation mode, and obtain the sensing signal from the lubricating oil metal shavings sensor output by the first output terminal of the routing circuit through the analog-to-digital conversion circuit, and determine the phase difference between the excitation signal and the sensing signal. In monitoring mode, a reference signal for demodulation is generated based on the phase difference and sent to the acquisition circuit. The detection result of metal shavings is obtained by analyzing the output signal of the analog-to-digital conversion circuit. The first input terminal of the routing circuit is connected to the first output terminal of the routing circuit, and the second input terminal of the routing circuit is connected to the second output terminal of the routing circuit.

2. The lubricating oil metal shavings monitoring device according to claim 1, characterized in that, The acquisition circuit includes: A preamplifier circuit used to initially amplify the received induced signal; A demodulation circuit connected to the preamplifier circuit is used to demodulate the output signal of the preamplifier circuit based on a reference signal. The output signal of the demodulation circuit is connected to the analog-to-digital converter circuit and the high-pass filter amplifier circuit, respectively, so that in the monitoring mode, when the sensed signal is a large particle signal, the processing circuit detects metal shavings based on the output signal of the demodulation circuit, and when the sensed signal is a small particle signal, the processing circuit detects metal shavings based on the output signal of the high-pass filter amplifier circuit. A high-pass filter amplifier circuit is used to perform high-pass filtering and amplification on the output signal of the demodulation circuit; Specifically, when the amplitude of the particle signal in the sensing signal reaches a preset first threshold, the sensing signal belongs to a large particle signal; when the amplitude of the particle signal in the sensing signal is not greater than the first threshold, the sensing signal belongs to a small particle signal.

3. The lubricating oil metal shavings monitoring device according to claim 2, characterized in that, The demodulation circuit is a single-channel demodulation circuit, and it demodulates the in-phase reference signal and quadrature reference signal in the reference signal by time-division multiplexing.

4. The lubricating oil metal shavings monitoring device according to claim 2, characterized in that, The demodulation circuit is a dual-channel demodulation circuit, and the demodulation circuit includes: The input terminal is connected to the output terminal of the preamplifier circuit, and is used to amplify the input signal by a factor of K; where K represents the amplification factor. The input terminal is connected to the output terminal of the pre-amplifier circuit, and is used to amplify the input signal by a factor of -K in the second amplifier circuit. A first switching circuit has its input terminal connected to the output terminal of the first amplifier circuit and its output terminal connected to the input terminal of the first low-pass filter circuit. The control terminal of the first switching circuit is used to receive the in-phase component reference signal in the reference signal, so as to control the on / off state of the first switching circuit through the in-phase component reference signal. A second switching circuit has its input terminal connected to the output terminal of the second amplifier circuit and its output terminal connected to the input terminal of the second low-pass filter circuit. The control terminal of the second switching circuit is used to receive the quadrature component reference signal in the reference signal, so as to control the on / off state of the second switching circuit through the quadrature component reference signal. The input terminal of the first low-pass filter circuit is connected to the output terminal of the first switching circuit. The input terminal is connected to the output terminal of the second low-pass filter circuit.

5. The lubricating oil metal shavings monitoring device according to claim 4, characterized in that, The first amplifier circuit includes: a first operational amplifier, a first resistor, and a second resistor; the second amplifier circuit includes: a second operational amplifier, a third resistor, and a fourth resistor; The non-inverting input of the first operational amplifier is used as the input of the first amplifier circuit to connect to the output of the preamplifier circuit. The inverting input of the first operational amplifier is connected to the second end of the first resistor and the first end of the second resistor, respectively. The first end of the first resistor is grounded, and the second end of the second resistor is connected to the output of the first operational amplifier, with the connection end serving as the output of the first amplifier circuit. The first end of the third resistor serves as the input terminal of the second amplifier circuit and is connected to the output terminal of the preamplifier circuit. The second end of the third resistor is connected to the inverting input terminal of the second operational amplifier and the first end of the fourth resistor, respectively. The non-inverting input terminal of the second operational amplifier is grounded. The output terminal of the second operational amplifier is connected to the second end of the fourth resistor, and the connection terminal serves as the output terminal of the second amplifier circuit.

6. The lubricating oil metal shavings monitoring device according to claim 4, characterized in that, The first low-pass filter circuit includes: a third operational amplifier, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a first capacitor, a second capacitor, and a third capacitor; The first terminal of the fifth resistor serves as the input terminal of the first low-pass filter circuit. The second terminal of the fifth resistor is connected to the first terminal of the first capacitor and the first terminal of the sixth resistor. The second terminal of the sixth resistor is connected to the first terminal of the seventh resistor and the first terminal of the second capacitor. The second terminal of the seventh resistor is connected to the first terminal of the third capacitor and the non-inverting input terminal of the third operational amplifier. The second terminal of the first capacitor is grounded, and the second terminal of the third capacitor is grounded. The inverting input terminal of the third operational amplifier is connected to the first terminal of the eighth resistor and the first terminal of the ninth resistor, respectively. The second terminal of the eighth resistor is grounded. The output terminal of the third operational amplifier is connected to the second terminal of the ninth resistor and the second terminal of the second capacitor, and the connection terminal serves as the output terminal of the first low-pass filter circuit.

7. The lubricating oil metal shavings monitoring device according to claim 4, characterized in that, The high-pass filter amplifier circuit is a dual-channel high-pass filter amplifier circuit, and the high-pass filter amplifier circuit includes: A first high-pass filter circuit whose input terminal is connected to the output terminal of the first low-pass filter circuit; A third amplifier circuit whose input terminal is connected to the output terminal of the first high-pass filter circuit and whose output terminal is connected to the analog-to-digital converter circuit; A second high-pass filter circuit whose input terminal is connected to the output terminal of the second low-pass filter circuit; The input terminal is connected to the output terminal of the second high-pass filter circuit, and the output terminal is connected to the analog-to-digital converter circuit of the fourth amplifier circuit.

8. The lubricating oil metal shavings monitoring device according to claim 7, characterized in that, The first high-pass filter circuit includes a fourth operational amplifier, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a fourteenth resistor, a fourth capacitor, a fifth capacitor, and a sixth capacitor. The first terminal of the fourth capacitor serves as the input terminal of the first high-pass filter circuit. The second terminal of the fourth capacitor is connected to the first terminal of the fifth capacitor and the first terminal of the tenth resistor. The second terminal of the tenth resistor is grounded. The second terminal of the fifth capacitor is connected to the first terminal of the sixth capacitor and the first terminal of the eleventh resistor. The second terminal of the sixth capacitor is connected to the first terminal of the twelfth resistor and the non-inverting input terminal of the fourth operational amplifier. The second terminal of the twelfth resistor is grounded. The inverting input terminal of the fourth operational amplifier is connected to the first terminal of the thirteenth resistor and the first terminal of the fourteenth resistor, respectively. The second terminal of the thirteenth resistor is grounded. The output terminal of the fourth operational amplifier is connected to the second terminal of the fourteenth resistor and the second terminal of the eleventh resistor, respectively, and the connection terminal serves as the output terminal of the first high-pass filter circuit.

9. The lubricating oil metal shavings monitoring device according to claim 1, characterized in that, A fifth amplifier circuit is also provided between the first input terminal and the first output terminal of the routing circuit.

10. The lubricating oil metal shavings monitoring device according to claim 1, characterized in that, The excitation circuit includes: a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, an eighteenth resistor, a fifth operational amplifier, and a first switching transistor; The first end of the fifteenth resistor serves as the control terminal of the excitation circuit and is connected to the processing circuit. The second end of the fifteenth resistor is connected to the non-inverting input terminal of the fifth operational amplifier and the first end of the sixteenth resistor. The inverting input terminal of the fifth operational amplifier is connected to a preset reference voltage. The output terminal of the fifth operational amplifier is connected to the second end of the sixteenth resistor and the control terminal of the first switching transistor. The second end of the first switching transistor is connected to the negative terminal of the first power supply. The first end of the first switching transistor is connected to the second end of the seventeenth resistor. The first end of the seventeenth resistor serves as the negative output terminal of the excitation circuit. The second end of the eighteenth resistor is connected to the positive terminal of the first power supply. The first end of the eighteenth resistor serves as the positive output terminal of the excitation circuit.

11. The lubricating oil metal shavings monitoring device according to claim 1, characterized in that, Also includes: A digital-to-analog converter circuit connected to the processing circuit, used to receive the simulation signal output by the processing circuit and output it to the third input terminal of the routing circuit after digital-to-analog conversion; The routing circuit also includes a switching switch. The first end of the switching switch serves as the second input terminal of the routing circuit, the second end of the switching switch serves as the third input terminal of the routing circuit, and the third end of the switching switch serves as the second output terminal of the routing circuit. In monitoring mode, the switching switch is in a first state, connecting the second input terminal and the second output terminal of the routing circuit. In simulation calibration mode, the switching switch is in a second state, connecting the third input terminal and the second output terminal of the routing circuit. The processing circuit is also used to: in simulation calibration mode, send a first simulation signal to the third input terminal of the routing circuit for software calibration; In simulation calibration mode, a second simulation signal is sent to the third input terminal of the routing circuit to calibrate the low-pass filter circuit structure in the acquisition circuit; In simulation calibration mode, a third simulation signal is sent to the third input terminal of the routing circuit to calibrate the high-pass filter circuit structure in the acquisition circuit.

12. The lubricating oil metal shavings monitoring device according to claim 11, characterized in that, The first simulated signal is the induced signal generated by superimposing the particle signal output by the particle signal generator by the processing circuit with the carrier signal output by the frequency synthesizer by the processing circuit.

13. The lubricating oil metal shavings monitoring device according to claim 11, characterized in that, Also includes: The first input terminal is connected to the output terminal of the lubricating oil metal shavings sensor, the second input terminal is connected to the output terminal of the digital-to-analog converter circuit, and the output terminal is connected to the first input terminal of the routing circuit, which is used as a multiplier for signal superposition. The processing circuit is also used to: in simulation calibration mode, output a particle signal through a particle signal generator, and superimpose the particle signal output by the particle signal generator with the sensing signal output by the lubricating oil metal shavings sensor when no metal shavings are generated to obtain a fourth simulation signal for software calibration.

14. The lubricating oil metal shavings monitoring device according to any one of claims 1 to 13, characterized in that, The routing circuit is further provided with a fourth input terminal and a third output terminal, and the fourth input terminal of the routing circuit is connected to the third output terminal of the routing circuit, and the third output terminal of the routing circuit is connected to the analog-to-digital conversion circuit, so that the output signal of the third output terminal of the routing circuit is sent to the processing circuit through the analog-to-digital conversion circuit. The fourth input terminal of the routing circuit is connected to the excitation circuit; The processing circuit is also used in self-test mode to apply an excitation signal through the excitation circuit when performing an excitation circuit self-test, and to obtain the signal output by the third output terminal of the routing circuit through the analog-to-digital conversion circuit. When the signal output by the third output terminal of the routing circuit is abnormal, the excitation circuit self-test is determined to be abnormal. In self-test mode, when the sensing loop self-test is performed, an excitation signal is applied through the excitation circuit to control the self-test line of the sensing loop to be turned on, so that the excitation signal is applied to the output terminal of the lubricating oil metal shavings sensor through the self-test line of the sensing loop, and the signal output by the first output terminal of the routing circuit is obtained through the analog-to-digital conversion circuit. When the signal output by the first output terminal of the routing circuit is abnormal, it is determined that the self-test of the sensing loop is abnormal. The self-test circuit of the sensing circuit is connected between the output terminal of the excitation circuit and the output terminal of the lubricating oil metal shavings sensor, and is in an open circuit state by default, only in a conducting state during the self-test of the sensing circuit.

15. The lubricating oil metal shavings monitoring device according to claim 14, characterized in that, When the excitation circuit self-test is performed, if the signal output from the third output terminal of the routing circuit is a DC signal, the processing circuit determines that the excitation circuit self-test is abnormal and the abnormality type is excitation circuit disconnection; if the signal output from the third output terminal of the routing circuit is a square wave signal, the processing circuit determines that the excitation circuit self-test is abnormal and the abnormality type is excitation circuit short circuit. When the induction circuit self-test is performed, if the signal output from the first output terminal of the routing circuit is a DC signal, the processing circuit determines that the induction circuit self-test is abnormal and the abnormality type is induction circuit disconnection; if the signal output from the first output terminal of the routing circuit is a square wave signal, the processing circuit determines that the induction circuit self-test is abnormal and the abnormality type is induction circuit short circuit.

16. The lubricating oil metal shavings monitoring device according to claim 14, characterized in that, An attenuator is also provided between the fourth input terminal and the third output terminal of the routing circuit.

17. A method for monitoring metal shavings in lubricating oil, characterized in that, The processing circuit applied in the lubricating oil metal shavings monitoring device as described in any one of claims 1 to 16 includes: In the adaptation mode, an excitation signal is applied through the excitation circuit, and the induction signal from the lubricating oil metal shavings sensor is obtained through the analog-to-digital conversion circuit, and the phase difference between the excitation signal and the induction signal is determined. In monitoring mode, a reference signal for demodulation is generated based on the phase difference and sent to the acquisition circuit. The detection result of metal shavings is obtained by analyzing the output signal of the analog-to-digital conversion circuit.

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