Infrared oil measuring instrument for driving infrared LED lamp through pulse signal

Abstract

The invention provides an infrared oil measuring instrument for driving an infrared LED lamp through a pulse signal, relates to the technical field of detection, and comprises the steps of generating a pulse width modulation signal, generating a constant peak current based on the pulse width modulation signal, and driving the infrared LED lamp with a preset characteristic absorption wave number to emit pulse infrared light. After passing through the measuring tube containing the solution to be measured, the pulse infrared light receives transmission light and converts the transmission light into electric signals, all the electric signals are processed to generate absorbance values, and the oil concentration is calculated based on the absorbance values and a preset calculation model. The LED light source intensity is improved through pulse driving, multi-wavelength characteristic detection and constant current control are combined, the measurement precision and the system stability are remarkably improved, the manufacturing cost is reduced, and the device is suitable for online or portable oil product monitoring scenes.

Description

Technical Field

[0001] The present application relates to the field of detection technology, and in particular to an infrared oil tester that drives an infrared LED lamp through a pulse signal. Background Art

[0002] Currently, according to internationally accepted standards, infrared photometry is the most common method for measuring oil in water. However, this method requires a specific wavelength of infrared light. Existing infrared photometric oil meters all use continuous-wavelength infrared spectrometers to achieve the required infrared wavelength. This approach results in high system complexity and high cost. Using infrared LEDs as a light source can significantly reduce the system complexity and price of infrared oil meters. However, infrared LEDs require a forward current to operate. When the DC current is too high, the diode heats up, reducing efficiency and potentially damaging the device. Summary of the invention

[0003] In view of the shortcomings of the existing technology, the present application provides an infrared oil measuring instrument that drives an infrared LED lamp through a pulse signal, comprising:

[0004] generating a pulse width modulation signal, and generating a constant peak current based on the pulse width modulation signal, and using the constant peak current to drive an infrared LED lamp with a preset characteristic absorption wave number to emit pulsed infrared light;

[0005] guiding the pulsed infrared light to pass through a measuring tube containing a solution to be tested, receiving the pulsed infrared light transmitted through the solution to be tested, and converting the pulsed infrared light into a first electrical signal corresponding to each of the preset characteristic absorption wavenumbers;

[0006] processing each of the first electrical signals to generate an absorbance value corresponding to each of the preset characteristic absorption wavenumbers;

[0007] Based on the absorbance value and a pre-calibrated coefficient, the oil concentration in the solution to be tested is calculated according to a preset calculation model.

[0008] As an optional implementation, it also includes:

[0009] Setting a reference optical path;

[0010] Using the constant peak current to drive at least one reference infrared LED lamp corresponding to the preset characteristic absorption wavenumber to emit reference pulsed infrared light and guide it through the reference optical path;

[0011] The microcontroller synchronously controls the infrared LED lamps of the sample light path and the reference light path to emit pulsed infrared light;

[0012] Receive the transmitted reference pulsed infrared light through the reference optical path and convert it into reference electrical signals corresponding to the preset characteristic absorption wavenumbers;

[0013] Based on the first electrical signal and the reference electrical signal, the microcontroller calculates a differential signal in real time;

[0014] Based on the differential signal, process each of the first electrical signals to generate absorbance values corresponding to the preset characteristic absorption wavenumbers.

[0015] As an alternative implementation, it further includes:

[0016] A feedback signal reflecting the intensity of the transmitted light in the sample optical path is monitored in real time by a sensor;

[0017] Based on the feedback signal, the microcontroller runs a control algorithm to adaptively adjust at least one of the following:

[0018] Adjust at least one optical path parameter of the sample optical path through an actuator;

[0019] Adjust at least one parameter of the pulse width modulation signal to control the light source intensity.

[0020] As an alternative implementation, it further includes: performing calibration before calculating the oil concentration in the solution to be measured, and the calibration includes:

[0021] For a standard solution with a known concentration, perform the following operations:

[0022] Drive the infrared LED lamp with the constant peak current to emit the pulsed infrared light;

[0023] Guide the pulsed infrared light through the measuring tube containing the standard solution;

[0024] Receive the pulsed infrared light transmitted through the standard solution and convert it into corresponding standard solution electrical signals corresponding to the preset characteristic absorption wavenumbers;

[0025] Process each of the standard solution electrical signals to determine the absorbance values of the standard solution corresponding to the preset characteristic absorption wavenumbers;

[0026] Based on the known concentration of the standard solution and its determined absorbance values, calculate the pre-calibrated coefficient and the correction factor of the pre-calibrated coefficient.

[0027] As an alternative implementation, the preset characteristic absorption wavenumbers are 2930 、2960 and 3030 ; The preset calculation model is as follows:

[0028]

[0029] Wherein, represents the calculated oil concentration, , , are the absorbance values measured at the corresponding wave numbers of 2930 , 2960 and 3030 respectively. X, Y, and Z represent the pre-calibrated coefficients corresponding to the absorbance of the target chemical bond, and F represents the correction factor of the pre-calibrated coefficient for the influence of aliphatic hydrocarbons on aromatic hydrocarbons. represents the volume of the extraction solution, represents the volume of the sample, and D represents the dilution factor of the extraction solution. represents the concentration of the blank sample.

[0030] As an alternative implementation, it further includes:

[0031] Real-time monitoring of the time variation of the absorbance value;

[0032] When it is detected that at least one of the absorbance values shows a rapid increase exceeding a preset threshold within a preset short time window, determine the relative change pattern of the absorbance values at the corresponding wave numbers during the rapid increase;

[0033] Based on a preset criterion, compare the relative change pattern with the spectral absorption characteristic pattern expected for the change in the oil substance concentration:

[0034] In response to the relative change pattern not conforming to the expected spectral absorption characteristic pattern, determine that a transient physical interference has occurred;

[0035] In response to the relative change pattern conforming to the expected spectral absorption characteristic pattern, determine that the real change in the oil concentration has occurred;

[0036] In response to determining that a transient physical interference has occurred, perform a preset suppression or marking process on the oil concentration result calculated based on the absorbance value during the rapid increase.

[0037] As an alternative implementation, the determination of the relative change pattern of the absorbance values at the corresponding wave numbers during the rapid increase includes:

[0038] Perform Fourier transform on the first electrical signal at the corresponding wave number during the rapid increase to obtain a frequency spectrum including the pulse infrared light pulse frequency and its harmonics;

[0039] Determine the amplitude ratio and / or relative phase relationship between the fundamental component of the pulse frequency and at least one of its harmonic components in the frequency spectrum;

[0040] Compare the currently determined amplitude ratio and / or relative phase relationship with preset reference harmonic structure parameters to generate a comparison result;

[0041] Based on the comparison result, determine whether the transient physical interference has occurred.

[0042] As an optional implementation manner, it further includes:

[0043] The microcontroller cooperatively adjusts the optical path parameters and the pulse width modulation signal parameters based on the feedback signal and the differential signal:

[0044] Obtain the current system state; wherein, the current system state includes at least one or a combination of multiple items of the current value of the feedback signal, the current value of the differential signal, the change rate of the feedback signal, the change rate of the differential signal, the result of determining that transient physical interference has occurred, and the set values of the current optical path parameters and the pulse width modulation signal parameters applied;

[0045] For a group of candidate cooperative adjustment amounts, use a preset state transition model to respectively predict the future state values of one or more measurement signal indicators based on the current system state after applying each candidate cooperative adjustment amount;

[0046] Wherein, each of the candidate cooperative adjustment amounts includes an adjustment combination of the optical path parameters and the pulse width modulation signal parameters;

[0047] Determine an optimization objective function according to the current system state and evaluate the future state values corresponding to each candidate cooperative adjustment amount; wherein, the optimization objective function aims to maximize the accuracy of oil concentration calculation;

[0048] Select the candidate cooperative adjustment amount that makes the optimization objective function optimal and control the actuator and the pulse width modulation signal based on the selected candidate cooperative adjustment amount.

[0049] Compared with the prior art, the present application drives an infrared LED lamp by combining a pulse width modulation signal with a constant peak current, which can instantaneously increase the light intensity while maintaining the LED lifespan and heat control, significantly improving the intensity of the transmitted optical signal and the measurement signal-to-noise ratio, and solving the problem of insufficient light intensity of low-cost LED light sources. Secondly, by using at least three infrared LEDs with specific wave numbers, it can accurately cover the characteristic absorptions of different groups in oil substances. Combining absorbance processing with a specific calculation model improves the accuracy of quantitative measurement of oil concentration and overcomes the problem of poor component discrimination ability in traditional single-band detection. Thirdly, through the complete closed-loop process of pulsed infrared light emission, transmission detection, signal processing, and concentration calculation, it realizes the simplification of the system structure, reduction of manufacturing cost, and consistency of the measurement process, and has good application stability and promotion value. Description of the Drawings

[0050] Figure 1 Schematic diagram of the implementation principle of measuring samples with infrared light of multiple wavelengths provided by the present application;

[0051] Figure 2 Schematic diagram of the waveform of the pulse driving frequency of multiple infrared wavelengths provided by the present application;

[0052] Figure 3 Circuit schematic diagram of the stroboscopic infrared LED driving circuit provided by the present application;

[0053] Figure 4 Circuit schematic diagram of the stroboscopic infrared optical signal reception and processing provided by the present application;

[0054] Figure 5 System flow chart of an infrared oil measurement method provided by the present application;

[0055] Figure 6 Flow chart of an infrared oil analyzer that drives an infrared LED lamp through a pulse signal provided by an embodiment of the present application. Detailed Embodiments

[0056] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments.

[0057] The research finds that for the problems of infrared LEDs during operation, the infrared LEDs can be made to operate in a pulsed state to avoid problems caused by excessive current. Additionally, pulsed operation can also increase the gain and efficiency of infrared LEDs. In the pulsed operation state, the diode can withstand a higher transient current and emit more photons in a short period of time, thereby increasing the output optical power and emission intensity. This can avoid the problem that the light source intensity is insufficient when the infrared LED is constantly on and it is difficult to generate infrared light with sufficient intensity. In the pulsed operation state, the light intensity, energy, and amplitude output by the infrared LED will all change. These changes are related to factors such as pulse width, frequency, and pulse duty cycle. Thus, pulsed operation can modulate and control the infrared LED so that its output light meets specific application requirements.

[0058] See Figure 6 As shown, the flowchart of an infrared oil analyzer that drives an infrared LED lamp through a pulse signal provided by an embodiment of the present application includes steps S101 to S104, where:

[0059] S101: Generate a pulse width modulation signal, and generate a constant peak current based on the pulse width modulation signal. Use the constant peak current to drive an infrared LED lamp with a preset characteristic absorption wavenumber to emit pulsed infrared light;

[0060] S102: Guide the pulsed infrared light through a measurement tube containing the solution to be measured. Subsequently, receive the pulsed infrared light transmitted through the solution to be measured and convert the pulsed infrared light into a first electrical signal corresponding to each of the preset characteristic absorption wavenumbers;

[0061] S103: Process each of the first electrical signals to generate an absorbance value corresponding to each of the preset characteristic absorption wavenumbers;

[0062] S104: Calculate the oil concentration in the solution to be measured according to a preset calculation model based on the absorbance value and a pre-calibrated coefficient.

[0063] Regarding the above S101:

[0064] In a specific implementation, the core control unit of the system, for example, can be a microcontroller (MCU), which is configured to generate a digital pulse width modulation (PWM) signal. The parameters of this PWM signal, such as frequency and duty cycle, can be precisely controlled and adjusted by the MCU according to a preset program or real-time requirements, thereby providing a basic control signal for generating optical pulses with specific characteristics later.

[0065] For example, a pulse frequency in the range of several hundred hertz to several thousand hertz and a duty cycle adjustable within a relatively wide range can be selected. Subsequently, the pulse width modulation signal generated by the MCU is sent to a specially designed constant current source circuit.

[0066] Referring to Figure 3 as shown Figure 3 is the circuit schematic diagram of the stroboscopic infrared LED drive circuit provided by this application; a peak constant current alternating power supply is generated by a PWM signal output from an MCU pin by a resistor R80, a PNP transistor Q12, a resistor R89, an adjustable zener diode D35, a resistor R111, and an NPN transistor Q7 to control the infrared LED lamp.

[0067] Among them, the resistor R80 is used to receive the PWM signal from the MCU; the PNP transistor Q12 and the resistor R89 constitute the input control part; the core constant current control part can be composed of an NPN transistor Q7, an adjustable zener diode D35 (and a resistor R111 (setting the reference current), etc.). The function of this constant current source circuit is to convert the input PWM signal representing the switching timing into a driving pulse with a constant peak current.

[0068] Exemplarily, when the PWM signal is at an effective level, the circuit is turned on, and the driving current quickly rises to the peak set by components such as D35 and R111 and remains relatively constant during this period; when the PWM signal is at an ineffective level, the circuit is quickly turned off, and the driving current drops to zero or close to zero.

[0069] The purpose of such a design is that regardless of small changes in the supply voltage or the LED's own parameters (such as the forward conduction voltage), the peak current flowing through the LED can remain stable, thereby ensuring good consistency in the intensity of each light pulse. Next, this pulse drive signal with a constant peak current is used to drive a specific infrared light-emitting diode (LED) light source.

[0070] In a specific implementation, three infrared LEDs can be selected, and the central emission wavelengths of these LEDs respectively correspond to the preset wave numbers that have characteristic absorption of oil substances.

[0071] Specifically, the preferred wave number combinations are , and , which respectively correspond to the characteristic absorption peaks of methylene, methyl, and aromatic ring C-H bonds in oil substances. The constant peak current pulse is applied to these three (or more, if other components need to be measured) specific infrared LEDs. The MCU can control the current pulse to be applied to different LEDs in sequence to achieve time-division multiplexing measurement of multiple wavelengths; or if the system design allows multi-channel parallel drive, it can also be controlled as needed.

[0072] Under the drive of the constant peak current, each selected infrared LED will emit pulsed infrared light corresponding to its characteristic wave number during its effective pulse period. Exemplarily, please refer toFigure 2 , Figure 2 is a waveform diagram of the pulse driving frequencies of multiple infrared wavelengths provided for this application; for example, the pulse width may be on the order of microseconds, and the peak current may range from several hundred milliamperes to several amperes. The specific parameters are set according to the LED characteristics and the required light intensity, and reference can be made to, but not limited to, Figure 2 the example parameters shown.

[0073] Exemplarily, in Figure 2 , the upper waveform corresponds to the normal power operation mode, with a pulse peak current of about 200 mA, a single period of 500 μs, where conduction and cutoff each account for 250 μs, and the overall duty cycle is 50%, which can provide a stable medium light flux while ensuring the thermal safety of the device. The lower waveform in the figure corresponds to the enhanced power operation mode, with a pulse peak current of about 2 A, a single pulse width of about 1 μs, an adjacent pulse interval of about 500 μs, and a duty cycle of less than 0.2%. The short-time high-current pulse is used to instantaneously increase the radiation power within the allowable range of the device's heat capacity to obtain a high peak light intensity. The two waveforms can be alternately or independently applied to infrared LEDs of different central wave numbers ( , , ) as needed to achieve a trade-off between measurement sensitivity and device life.

[0074] Due to the adoption of the pulse driving method and the application of a relatively high peak current, these infrared LEDs can instantaneously emit a stronger optical power than that under DC driving, thus meeting the signal intensity requirements of subsequent optical measurements. At the same time, since the pulse duty cycle is usually low, the average power consumption and heat generation of the LEDs can be controlled within a safe range.

[0075] In this way, the output result of step S101 is to generate a series of pulsed infrared lights with stable peak intensities and specific time sequences at the preset characteristic wave numbers, preparing for subsequent measurement through the sample.

[0076] Regarding the above S102:

[0077] In a specific implementation, the pulsed infrared light emitted from the infrared LED light source is precisely guided and directed through a specially designed measurement tube. The structure of this measurement tube can refer to Figure 1 , Figure 1 which is a schematic diagram of the implementation principle for measuring samples of infrared light of multiple wavelengths provided for this application, and is mainly used to accommodate the solution to be measured. The solution to be measured is usually a water sample containing the oil substance to be measured or its extract, such as a solution obtained using tetrachloroethylene as an extractant. The measurement tube has a definite optical path length and is provided with, at both ends in the optical path direction, for the selected infrared wave numbers (such as , and An optical window with good transmittance.

[0078] When the pulsed infrared light travels through the solution to be measured in the measuring tube, the oil substances present in the solution will absorb part of the energy of the infrared light at their corresponding characteristic absorption wave numbers, and the absorption degree follows Lambert-Beer's law. Therefore, the intensity of the pulsed infrared light after passing through the solution will be attenuated, and this attenuation degree directly reflects the concentration information of the oil components in the solution to be measured.

[0079] At the light exit end of the measuring tube, one or more infrared light receivers (also known as infrared sensors) are strategically placed to ensure that the pulsed infrared light that has passed through the solution to be measured and whose intensity has been attenuated can be effectively received. The selection of the sensor needs to ensure that its spectral response covers the infrared wave numbers used and has a fast enough response speed to capture the pulsed signal. The system can be designed to use a single sensor with time-division driving of the light source, or as Figure 1 shown, multiple sensors are set up to perform parallel detection corresponding to different wavelengths.

[0080] The core function of the infrared light receiver is to convert the received optical signal in the form of a pulse into a corresponding electrical signal with a varying amplitude in real time, which is the first electrical signal. This first electrical signal also exhibits pulse characteristics, and its amplitude or pulse integral value is proportional to the intensity of the transmitted light at the corresponding wave number. Therefore, for the pulsed infrared light of each wave number, a corresponding first electrical signal pulse sequence will be generated at the output end of the receiver, and this sequence is the basis for subsequent signal processing and concentration calculation.

[0081] Regarding the above S103:

[0082] In step S102, the infrared light receiver converts the pulsed light signal after passing through the sample into the first electrical signal. After entering step S103, a series of processes need to be performed on this first electrical signal that is usually relatively weak and has pulse characteristics to extract stable and accurate absorbance information. Referring to Figure 4 shown, Figure 4 is the circuit schematic diagram for the reception and processing of the stroboscopic infrared light signal provided by this application. The first electrical signal is first input into a signal amplification circuit. This amplification circuit can be composed of a low-noise operational amplifier (such as U7A in Figure 4 ) and precisely configured peripheral resistors and capacitors (such as R141, R155, C281, C250, etc.). Its function is to effectively amplify the weak first electrical signal to obtain a second electrical signal with a higher amplitude for subsequent processing.

[0083] Considering the noise that may be introduced by the pulsed light source and the environment, the amplified second electrical signal needs to be filtered. In this embodiment, a two-stage low-pass filtering strategy can be adopted to obtain a good filtering effect. The second electrical signal is first preliminarily filtered by an active low-pass filter, which can be composed of an operational amplifier (such as Figure 4 U7B in Figure 4 ) and corresponding resistors and capacitors (such as R214, R154, C152). It can filter out high-frequency noise while buffering or further amplifying the signal and start to smooth the pulse waveform. Subsequently, the signal that has passed through the first-stage filtering is further filtered by a passive RC low-pass filter (for example,

[0084] composed of R203 and C152 in

[0085] ). The combination of these two-stage filters can effectively suppress noise and smooth the originally pulsed signal waveform into a third electrical signal that is nearly direct current with an amplitude approximately equal to the average light intensity during the pulse period. The third electrical signal obtained by processing, whose voltage or current amplitude represents the average transmitted light intensity after passing through the sample at a specific wavenumber, needs to be digitized next for the MCU to process. This third electrical signal is fed into an analog-to-digital (A / D) conversion circuit. The A / D converter samples and quantizes the third electrical signal with sufficient sampling accuracy (such as 12 bits or higher) and an appropriate sampling rate, converting it into a series of digital values. These digital values represent the transmitted light intensity (I) at the corresponding wavenumber. For time-division multiplexed multi-wavelength measurements, the MCU will associate the A / D conversion result with the corresponding wavenumber according to the currently driven LED wavelength. These digitized intensity signals are then transmitted to the MCU. . This value can be obtained by measuring a reference substance (for example, a pure extraction solvent without oil or a blank sample) before measuring the sample or periodically, and storing the measured corresponding digital intensity value. After obtaining the digital value I of the sample transmitted light intensity and the corresponding digital value of the reference light intensity at a specific wavenumber, the MCU performs the calculation: , or adopts other equivalent calculation methods (such as ), so as to obtain the absorbance value at this wavenumber. For , and these three wavenumbers, the MCU will calculate the corresponding absorbance values , and These calculated absorbance values are the key input data necessary for performing the final oil concentration calculation in step S104.

[0086] Regarding the above S104:

[0087] In a specific implementation, the MCU will use the real-time measured absorbance values, combined with the calibration parameters pre-stored in the internal memory, and calculate the final oil concentration in the solution to be measured according to a preset calculation model.

[0088] The pre-calibrated coefficients refer to the parameters obtained by executing an independent calibration program. This calibration program is usually carried out when the instrument is first used or during regular maintenance. By measuring standard solutions with known concentrations containing different types of hydrocarbons (such as n-hexadecane, isooctane, benzene) and solving a system of simultaneous equations, the coefficients X (corresponding to group), Y (corresponding to group), Z (corresponding to the aromatic ring C-H group), and the correction factor F for correcting the influence of aliphatic hydrocarbons on the measurement of aromatic hydrocarbons are determined. These calibrated coefficients X, Y, Z, and F are stored as important bases for subsequent measurement of unknown samples.

[0089] The preset calculation model, in this embodiment, specifically uses the following mathematical formula to calculate the oil concentration :

[0090]

[0091] In this calculation model, in addition to the real-time measured absorbance values , , and the pre-stored calibration coefficients X, Y, Z, F, it also includes some parameters related to sample preparation or measurement conditions. represents the volume of the extractant (such as tetrachloroethylene) used during sample extraction; represents the volume of the original water sample; D represents whether the extract is diluted before use and the dilution factor (if not diluted, then D = 1); represents the background concentration or absorbance correction value measured for the blank sample (i.e., pure extractant without oil or blank water sample processed through the same process), and this value is usually determined during calibration or zero calibration. These parameters , , D, values are usually known and can be input through the user interface or preset in the system settings.

[0092] When performing calculations, the MCU takes the absorbance values obtained in the current measurement cycle , , , as well as the stored calibration coefficients X, Y, Z, F, together with the set sample parameters , , D, , and substitutes them into the above-mentioned preset calculation model formula for arithmetic operations. The result finally obtained from the operations represents the total concentration of oil substances contained in the original water sample to be measured, and its unit is milligrams per liter (mg / L).

[0093] After the calculation is completed, the obtained oil concentration value can be displayed to the user in real time through the display interface of the instrument (such as an LCD screen), or stored in the internal memory of the MCU to form a historical data record, or uploaded to a host computer, PLC or data acquisition system through a communication interface (such as RS485, 4-20mA analog output, etc.) for process monitoring, data analysis or alarm control. Thus, a complete oil concentration measurement process is completed.

[0094] Exemplarily, three infrared LED light sources with wave numbers of , and are selected. The infrared LED light sources are driven by a pulse period as shown in Figure 2 . Then, the n-hexadecane standard solution, isooctane standard solution and benzene standard solution are automatically injected into the measurement tube in sequence and their absorbance values for the above-mentioned wavelength infrared light are measured , , , and the above absorbance measurement values are substituted into the formula:

[0095]

[0096] where is the content of oil in tetrachloroethylene, and the unit is mg / L; , , are the absorbances measured at the corresponding wave numbers respectively; X is the coefficient corresponding to the absorbance of the C—H bond in the CH2 group, mg / L / absorbance; Y is the coefficient corresponding to the absorbance of the C—H bond in the CH3 group, mg / L / absorbance; Z is the coefficient corresponding to the absorbance of the C—H bond in the aromatic ring, mg / L / absorbance; F is the correction factor for the influence of aliphatic hydrocarbons on aromatic hydrocarbons, that is, the ratio of the absorbance of n-hexadecane at 2930 to 3030 ;

[0097] First, the instrument needs to obtain the absorbance coefficients X, Y, Z, and F by measuring standard solutions. Three sets of data can be obtained through the measurement of three standard solutions, and the values of the absorbance coefficients X, Y, and Z can be obtained by solving equations. Since n-hexadecane and isooctane do not contain aromatic hydrocarbons, Therefore, F can be calculated from the , measurement results of the n-hexadecane standard working solution and the isooctane standard working solution:

[0098]

[0099] The other three coefficients X, Y, and Z can be obtained by solving simultaneous equations of the known concentrations of three different standard solutions and the absorbances of the three different standard solutions under the above three infrared LED lights. After all four coefficients X, Y, Z, and F are obtained, the instrument automatically injects the sample to be measured into the measuring tube. After extraction with tetrachloroethylene, the absorbance of the infrared rays at this time is measured , , , and substituted into the calculation formula for the oil concentration in the sample:

[0100]

[0101] Exemplarily, please refer to Figure 5 , Figure 5 which is a system flow chart of an infrared oil measurement method provided by this application. The core controller microcontroller (MCU) generates a pulse width modulation (PWM) signal, and this signal controls the infrared LED light source to emit pulsed infrared light through a constant current source generation circuit. The pulsed infrared light passes through the solution to be measured (the sample may be provided by a sampling device and processed by an extraction device), and the transmitted light is received by an infrared sensor. The electrical signal output by the sensor is processed successively by a signal amplification circuit, a filtering circuit, and an analog-to-digital (A / D) conversion circuit, and the finally formed digital signal is fed back to the MCU. The MCU can also control the sampling device to sample the sample. The MCU performs subsequent processing based on the received digital signal, such as calculating the absorbance and the final oil concentration value. The entire process forms a closed-loop operation under the control of the MCU.

[0102] In this way, this application uses a low-cost infrared light-emitting diode (LED) to replace the high-cost and structurally complex infrared spectrometer used in the traditional infrared photometry method as the light source. At the same time, the supporting drive circuit and signal processing circuit are relatively simplified, which greatly reduces the manufacturing cost of the entire oil analyzer, makes the system structure simpler and more compact, and is convenient for miniaturization and integration.

[0103] In view of the problems that direct use of LEDs may suffer from insufficient light intensity or be prone to damage under high current, the present application adopts a method of using a pulse-width modulation (PWM) signal to control a constant-current source to generate a constant peak current for pulsed driving of infrared LEDs. This driving method allows a peak current much higher than the DC rated value to be applied within an extremely short pulse width, enabling the LED to instantaneously emit infrared light strong enough to meet the signal intensity required for quantitative measurement. Meanwhile, the design of the constant peak current ensures the stability of the intensity of each light pulse, unaffected by small fluctuations in the power supply voltage or the LED's own parameters.

[0104] Due to the use of pulsed driving with a generally low duty cycle, the average power consumption and heat generation of the LED are effectively controlled, avoiding problems such as overheating, reduced efficiency, and even damage caused by continuous high-current operation, thereby improving the working reliability and service life of the infrared LED light source.

[0105] The method of the present application not only solves the problem of low-cost light sources, but also, by selecting at least three infrared LEDs corresponding to the characteristic absorption wave numbers of oil substances, and combining Lambert-Beer's law and a specific calculation model based on pre-calibrated coefficients, comprehensively processes multi-wavelength absorbance information, can distinguish the contributions of different types of hydrocarbon groups and perform quantitative calculations. This enables the method to achieve the quantitative analysis accuracy required by traditional infrared photometry, rather than just qualitative or semi-quantitative detection.

[0106] As an optional implementation, in order to further improve the measurement stability and anti-interference ability, the present application can also adopt a measurement scheme based on dual-beam differential. In this scheme, in addition to the sample optical path containing the solution to be measured (as described for S101 and S102 above), the system also parallelly sets up a reference optical path. The purpose of this reference optical path is to provide a reference signal for real-time comparison with the sample optical path to eliminate the interference of factors such as light source intensity fluctuations, detector response drift, circuit common-mode noise, and certain environmental factors (such as the general influence of temperature changes on optical components) on the measurement results.

[0107] The reference optical path can be constructed in various ways. For example, a reference cell with a structure similar to the sample measurement tube and the same optical path length can be set up, filled with a pure solvent without the oil substance to be measured (such as tetrachloroethylene used in sample extraction) or a specific reference solution. At the same time, corresponding infrared light sources and receivers are also set up on the reference optical path. Specifically, using the same constant peak current as that driving the LED in the sample optical path (emitting pulsed infrared light corresponding to the first electrical signal), at least one (or a group, corresponding to multiple wave numbers) reference infrared LED lamp is driven. The emission wave numbers of these reference infrared LED lamps are the same as or precisely matched with those of the LEDs used in the sample optical path (for example, also select 、 and of the LED). The reference pulsed infrared light emitted by the reference infrared LED is guided through the reference optical path, for example, through a reference cell filled with pure solvent. Appropriate optical designs, such as elements like beam splitters, mirrors, lenses, etc., are used to ensure that the optical conditions of the sample optical path and the reference optical path are as consistent as possible (except for the sample itself).

[0108] To ensure the effectiveness of differential measurement, the microcontroller (MCU) is configured to synchronously control the pulsed infrared light emitted by the infrared LED lights in the sample optical path and the reference optical path. This synchronization can be achieved by driving the LEDs of the same wavelength corresponding to the sample and the reference to emit light at the same moment, or by driving the two alternately at a very high frequency so that the time difference between the two measurements is small enough to consider that the two optical paths are measured under approximately the same conditions. The MCU realizes this synchronous driving by outputting synchronous PWM signals to their respective (or shared, but time-division switched) constant current source circuits.

[0109] At the end of the reference optical path, an infrared light receiver is also provided. Its characteristics should be strictly matched or calibrated with the receiver in the sample optical path and is used to receive the reference pulsed infrared light transmitted through the reference optical path. This receiver converts the received optical signal into a reference electrical signal corresponding to each of the preset characteristic absorption wave numbers. This reference electrical signal mainly reflects the actual pulsed intensity of the light source, the transmission characteristics of the optical path (when there is no sample absorption), and the response characteristics of the detector.

[0110] Subsequently, the MCU receives the first electrical signal (a digital signal after amplification, filtering, and A / D conversion) from the sample optical path and simultaneously receives the reference electrical signal (also processed and A / D converted) from the reference optical path. For each synchronous (or fast-alternating) measurement pulse at each wave number, the MCU calculates the differential signal in real time based on these two signals. The differential signal can be calculated in various ways, such as calculating the ratio of the intensities of the two signals (Ratio = First electrical signal / Reference electrical signal) or the difference (Difference = First electrical signal - Reference electrical signal). Using the ratio method can more directly reflect the transmittance or absorbance information of the sample.

[0111] Finally, and this is a crucial step in the dual - optical - path differential measurement, the subsequent absorbance calculation method has changed. Instead of simply calculating the absorbance using the first electrical signal (sample signal) and the pre - stored baseline I0, the sample signal (the first electrical signal) is processed based on the just - calculated differential signal to generate the absorbance value. For example, if the differential signal is calculated as a ratio , and it can be considered that the reference signal represents the effective incident light intensity at that moment (or is in a stable proportion to it), then the absorbance can be directly (or after a simple conversion) obtained from Calculated. Among them, The transmitted light intensity detected by the sample optical path receiver at this wavenumber (or the digital quantity after its A / D conversion), corresponding to the first electrical signal in the previous text; in this way, before calculating the absorbance, the common noise and drift components of the two optical paths have been effectively cancelled during the calculation of the differential signal, so as to obtain a more stable and accurate absorbance value. , , , and these values will be used for the final concentration calculation in step S104. This differential measurement method significantly improves the ability of the instrument to resist environmental interference and its own drift.

[0112] As an optional implementation manner, in order to further improve the measurement accuracy and stability of the oil detector in a complex or changing environment, the present application also provides an implementation manner including an adaptive adjustment ability.

[0113] Specifically, this implementation manner introduces one or more sensors for real-time monitoring of key parameters that can reflect the current measurement state of the sample optical path and generating feedback signals.

[0114] A preferred embodiment is to monitor the transmitted light intensity in the sample optical path. For example, the first electrical signal output by the main infrared sensor of the sample optical path (i.e., the infrared light receiver mentioned in S102) (or the signal processed by part of S103) can be directly used as the feedback signal source; alternatively, a dedicated light intensity monitoring element (such as a photodiode, a photoresistor, etc.) can be additionally provided in the optical path to generate an independent feedback signal. The amplitude or change of this feedback signal can reflect in real time the transmitted light intensity fluctuations caused by factors such as sample turbidity changes, slight optical path offsets, light source aging, or window contamination.

[0115] The MCU continuously receives and processes this real-time feedback signal. A preset control algorithm runs inside the MCU for analyzing the feedback signal and deciding whether and how to perform adaptive adjustment of system parameters. Common examples of control algorithms include the PID control algorithm. This algorithm compares the value of the real-time monitored feedback signal with a preset target value (for example, the desired transmitted light intensity level, which is usually set within the optimal linear response range of the detector), calculates the deviation, and calculates the corresponding control output quantity according to the PID parameters, including the proportional coefficient Kp, the integral time Ti, and the differential time Td, aiming to drive the system to eliminate the deviation and make the feedback signal stable near the target value.

[0116] According to the output result of the control algorithm, the MCU will adaptively adjust at least one of the following system parameters to achieve closed-loop feedback control:

[0117] Adjust at least one optical path parameter of the sample optical path: In this adjustment method, the system is equipped with actuators, such as precision stepper motors, piezoelectric ceramic drivers, or servo motors, etc. These actuators are configured to be able to precisely adjust the position, angle, or state of a certain or certain optical elements or mechanical components in the sample optical path. For example, the actuator can finely adjust the position of the measurement tube (sample cell) relative to the light beam, or adjust the focal length of the lens in the optical path, the angle of the mirror, etc. The MCU issues instructions to the actuator according to the output of the control algorithm, driving it to make small physical adjustments, aiming to compensate for the optical path offset or misalignment that may be caused by mechanical vibration, thermal expansion and contraction, or sample flow, so as to optimize the reception efficiency and stability of the optical signal.

[0118] Adjust at least one parameter of the pulse width modulation signal to control the light source intensity: In this adjustment method, the MCU directly adjusts the parameters of the PWM signal generated by itself for driving the infrared LED. The specifically adjustable parameters include, for example, the duty cycle or frequency of the PWM signal. By increasing the duty cycle or adjusting the frequency in some cases, the average current or peak current for driving the LED can be increased (if the constant current source design allows a certain range of peak adjustment), thereby increasing the average emission light intensity or peak light intensity of the infrared LED. This adjustment method is mainly used to compensate for the excessive signal attenuation caused by too high sample concentration or too large turbidity, or to compensate for the slow decrease in light intensity caused by the aging of the LED light source itself, aiming to maintain the signal intensity at the receiving end at a suitable level that is conducive to subsequent processing and calculation.

[0119] The system can be designed to mainly adopt one of the above two adjustment methods, or the MCU can intelligently select which adjustment method to enable according to the characteristics of the feedback signal, the magnitude of the deviation, or the change rate. The introduction of this adaptive adjustment mechanism enables the oil analyzer to better adapt to the changes of samples and the environment, and maintain the stability and accuracy of the measurement.

[0120] As an optional implementation method, during the actual measurement process, especially during on-line monitoring or processing of complex samples, transient physical interferences such as large air bubbles, suspended solids, or sudden changes in turbidity may be encountered. These interferences will cause a sharp drop in the transmitted light intensity, resulting in a false and non-real rapid increase in the absorbance value calculated based on Lambert-Beer's law, seriously affecting the accuracy of the measurement results. To solve this problem, this application provides a specific processing method for distinguishing the real change in oil concentration from transient physical interferences.

[0121] This method is executed after obtaining the absorbance values corresponding to each preset characteristic absorption wavenumber through step S103. First, the MCU monitors these absorbance values in real time and records their changes over time. The MCU sets a preset threshold to determine whether the absorbance value has a "rapid increase". This threshold can be set based on the absolute change amount, relative change rate of the absorbance value, or the change amplitude within a specified short time window.

[0122] When the MCU detects that the change in the absorbance value of at least one wavelength exceeds the preset threshold within a short time (e.g., within several measurement cycles), the system does not immediately consider this as an increase in oil concentration. Instead, it starts an analysis program to determine the relative pattern of the changes in the absorbance values at all three wavenumbers during this rapid increase. This "relative change pattern" can refer to the proportional relationship of the increased values of the absorbance at each wavenumber, or a combination of the shape characteristics of their dynamic curves changing over time.

[0123] Next, the MCU compares the currently observed "relative change pattern" with an expected spectral absorption characteristic pattern representing the true change in the oil substance concentration according to the preset criteria. This expected spectral absorption characteristic pattern is established based on the spectral characteristics of the oil substance itself. For example, usually, when the oil concentration increases, and will increase significantly and maintain a certain proportional relationship, while increases relatively less or has a specific association with (represented by factor F).

[0124] The result of the comparison triggers the decision logic: When the currently observed "relative change pattern" does not conform to the expected spectral absorption characteristic pattern of the oil (for example, it is found that has an abnormally large increase amplitude, or the absorbance values at the three wavelengths increase almost synchronously and proportionally, which is more like the characteristic of non-selective light shielding or scattering), the MCU determines that the current event is a transient physical interference. Conversely, when the currently observed "relative change pattern" conforms to the expected spectral absorption characteristic pattern of the oil, the MCU determines it as a true change in the oil concentration.

[0125] Finally, corresponding processing is performed according to the determined result. In response to determining that a transient physical interference has occurred, the MCU performs a preset suppression or marking process on the oil concentration result calculated based on these abnormal absorbance values during the duration of the interference. Such processing can include: marking the concentration value calculated during this time period as invalid data or in an "interference state" and differentiating it during output or recording; or maintaining the display of the previous valid concentration measurement value until the interference is removed and the signal returns to normal; or not updating the concentration value, etc.

[0126] In this way, false high-concentration alarms or recordings caused by physical interferences such as large air bubbles and instantaneous high turbidity can be effectively avoided, and the reliability of the measurement results can be significantly improved. Only when it is determined that the oil concentration has a real change, the calculated concentration result is regarded as valid and normally output or recorded.

[0127] As an optional implementation manner, in order to further improve the recognition accuracy of transient physical interferences, the present application provides a more precise interference determination method. After detecting a suspected interference situation where the absorbance value rapidly and significantly increases, instead of directly comparing the relative change pattern of the absorbance itself, the analysis goes deep into the frequency-domain characteristics of the signal.

[0128] Specifically, when the judgment condition for suspected interference is triggered, the microcontroller (MCU) performs a Fourier transform (such as the fast Fourier transform FFT) on the first electrical signal corresponding to the wave number within the time period when the "rapid increase" event occurs.

[0129] Among them, the electrical signal for which the Fourier transform is performed at this time is a digitized time series sample after A / D conversion.

[0130] The purpose of performing the Fourier transform is to convert the signal in the time domain into a frequency-domain representation, so as to obtain a frequency spectrum containing the frequency components of the signal, their intensities, and phase information. Since the present application uses pulsed infrared light, the frequency spectrum should contain the fundamental frequency of the pulsed signal driving the LED ( , determined by the PWM frequency) and significant components of its integer multiple harmonic frequencies (2 , 3 ,...).

[0131] Next, the MCU analyzes the calculated frequency spectrum to determine the amplitude and / or phase of the fundamental component of the pulsed frequency ( ) and at least one of its harmonic components (such as the second harmonic or the third harmonic ). Based on this amplitude and phase information, parameters that can characterize the "shape" or "structure" of the current pulsed signal are calculated. Specifically, it can be the amplitude ratio of the harmonic component to the fundamental component (such as ), and / or the relative phase relationship of the harmonic component to the fundamental component (such as ). These ratios and relationships together constitute the "harmonic structure characteristics" of the current signal.

[0132] Then, the MCU compares the currently calculated amplitude ratio and / or relative phase relationship with the preset reference harmonic structure parameters to generate a comparison result. This "reference harmonic structure parameter" represents the harmonic structure expected to be observed under normal measurement conditions or when the oil concentration undergoes a real change. This reference parameter can be obtained through theoretical calculations or, more commonly, through statistical learning by performing Fourier transform analysis on the signals of interference-free standard samples with different concentrations during the instrument calibration stage or during operation, and is stored in the MCU.

[0133] Finally, based on the comparison result, the MCU determines whether a transient physical interference has occurred. The determination logic can be: If the currently calculated harmonic structure parameters (amplitude ratio and / or phase relationship) deviate significantly from the preset reference harmonic structure parameters (for example, the relative amplitude of a certain harmonic increases abnormally, or the phase relationship is severely distorted, exceeding the preset tolerance range), it indicates that the shape of the received optical pulse is severely interfered, which is likely not caused by the absorption change of the oil concentration but by scattering, diffraction, or occlusion caused by physical factors such as bubbles and turbidity. In this case, the MCU determines that a transient physical interference has occurred. If the comparison result shows that the current harmonic structure is consistent with the reference parameter within the preset tolerance range, it is considered that the signal change is mainly caused by absorption (or at least cannot be determined as interference by this method), and it is determined that no (or not detected) transient physical interference has occurred. This determination result can then be used to trigger subsequent processing steps.

[0134] This method based on harmonic structure analysis utilizes the deep information in the signal frequency domain and is more sensitive and robust to distinguishing certain types of interference compared to the analysis based only on the time-domain absorbance mode.

[0135] As an alternative implementation, in order to achieve more accurate, forward-looking, and intelligent coordinated adjustment of the parameters of the infrared oil analyzer system, the present application further proposes an implementation based on model predictive control. This method aims to predict the future effects of different control strategies, dynamically adjust the optimization goal according to the current system state, and select the optimal coordinated adjustment action to optimize the accuracy of subsequent oil concentration measurement and the system stability.

[0136] In a specific implementation, the microcontroller MCU collects and constructs the current system state in real time. The current system state includes the current value of the feedback signal, the current value of the differential signal, the change rate of the feedback signal, the change rate of the differential signal, the determination result of whether a transient physical interference occurs, and optionally, at least one or a combination of multiple items of the currently applied optical path parameter setting value and the pulse width modulation signal parameter setting value. The current value of the feedback signal and the current value of the differential signal respectively reflect the current light intensity characteristics of the sample optical path and the reference optical path, and the change rate is obtained by differential calculation of two adjacent measurement periods. The transient physical interference determination result is derived from the output of the aforementioned absorbance change pattern analysis and spectral structure analysis module.

[0137] Based on the above current system state, the microcontroller generates a number of candidate co-adjustment amounts. Each candidate co-adjustment amount includes a combination of a set of optical path parameter adjustment amounts and pulse width modulation signal parameter adjustment amounts to be applied, and the combination covers fine-tuning changes of different amplitudes and directions, such as micro-shifting of the optical path focus, fine-tuning of the optical path length, fine-tuning of the pulse duty cycle or pulse frequency.

[0138] For each candidate co-adjustment amount, the microcontroller uses the state transition model stored internally to perform simulation and deduction based on the current system state. The state transition model is used to predict the evolution trends of the feedback signal, the differential signal, and their change rates in one or more future measurement periods if a specific candidate co-adjustment amount is applied. Specifically, the state transition model adopts a multivariate linear regression model trained based on the system historical data, and its form includes but is not limited to:

[0139] Next value of the feedback signal = × Current value of the feedback signal + × Current value of the differential signal + × Change rate of the feedback signal + × Change rate of the differential signal + × Interference determination flag + × Optical path parameter adjustment amount + × Pulse signal parameter adjustment amount + ;

[0140] Next value of the differential signal = × Current value of the feedback signal + × Current value of the differential signal + × Change rate of the feedback signal + × Change rate of the differential signal + × Interference determination flag + × Optical path parameter adjustment amount + × Pulse signal parameter adjustment amount + .

[0141] Among them, ~ 、 ~ 、 、 are the model coefficients obtained through least - squares regression analysis during the system calibration or debugging phase. If the system design requires real - time adaptation to environmental changes, the state - transition model can also be updated online based on newly collected data during operation, and the coefficients can be adjusted in real - time using a sliding - window regression or recursive least - squares method.

[0142] The simulation deduction adopts a forward - recursive method. After each candidate collaborative adjustment amount is applied, based on the above - mentioned state - transition model, the predicted values of the feedback signal value, differential signal value, and their change rates in the next N measurement cycles (e.g., N = 3) are recursively calculated. During the deduction process, the current system state is used as the initial condition and gradually substituted into the simulation.

[0143] For each candidate collaborative adjustment amount, the microcontroller evaluates it using an optimization objective function based on the deduced future state. The optimization objective function aims to maximize the accuracy of future oil - concentration calculation and usually includes a weighted combination of signal - strength stability index, signal - to - noise ratio index, and interference - recovery speed index. The optimization objective function takes maximizing the signal - to - noise ratio as the main weight under normal measurement conditions and dynamically adjusts to take rapid recovery to stability as the main weight when a transient physical interference state is detected.

[0144] By calculating the optimization - objective - function values corresponding to each candidate collaborative adjustment amount respectively, the microcontroller selects the candidate collaborative adjustment amount with the highest score as the adjustment action for this round. Subsequently, the microcontroller generates specific execution instructions and sends them to the optical - path adjustment actuator and the pulse - width modulation signal generation module respectively to update the optical - path parameters and light - source intensity parameters of the system in real - time.

[0145] The above - mentioned intelligent collaborative adjustment actions based on model prediction are periodically repeated, enabling the infrared oil analyzer to continuously optimize its measurement conditions according to the changes in the system operation state, and improving the accuracy, stability, and anti - interference ability of the overall oil - concentration measurement.

[0146] Those of ordinary skill in the art can realize that, combining the units and algorithm steps of each example described in the embodiments disclosed in this application, they can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of this application.

Claims

1. An infrared oil detector that drives an infrared LED lamp through a pulse signal, characterized in that, Including: Generating a pulse width modulation signal, generating a constant peak current based on the pulse width modulation signal, and driving an infrared LED lamp with a preset characteristic absorption wavenumber using the constant peak current to emit pulsed infrared light; Guiding the pulsed infrared light through a measuring tube containing the solution to be measured, receiving the pulsed infrared light transmitted through the solution to be measured, and converting the pulsed infrared light into a first electrical signal corresponding to each of the preset characteristic absorption wavenumbers; Processing each of the first electrical signals to generate absorbance values corresponding to each of the preset characteristic absorption wavenumbers; Calculating the oil concentration in the solution to be measured based on the absorbance values and a pre-calibrated coefficient according to a preset calculation model.

2. The infrared oil detector that drives an infrared LED lamp through a pulse signal according to claim 1, wherein Further including: Setting a reference optical path; Driving at least one reference infrared LED lamp corresponding to the preset characteristic absorption wavenumber using the constant peak current to emit reference pulsed infrared light and guiding it through the reference optical path; Synchronously controlling, by a microcontroller, the infrared LED lamps in the sample optical path and the reference optical path to emit pulsed infrared light; Receiving the reference pulsed infrared light transmitted through the reference optical path and converting it into a reference electrical signal corresponding to each of the preset characteristic absorption wavenumbers; Based on the first electrical signal and the reference electrical signal, the microcontroller calculates a differential signal in real time; Based on the differential signal, processing each of the first electrical signals to generate absorbance values corresponding to each of the preset characteristic absorption wavenumbers.

3. An infrared oil detector that drives an infrared LED lamp through a pulse signal according to claim 2, characterized in that, Further including: Real-time monitoring, by a sensor, of a feedback signal reflecting the intensity of the transmitted light in the sample optical path; Based on the feedback signal, the microcontroller runs a control algorithm to adaptively adjust at least one of the following: Adjusting at least one optical path parameter of the sample optical path through an actuator; Adjusting at least one parameter of the pulse width modulation signal to control the light source intensity.

4. An infrared oil detector that drives an infrared LED lamp through a pulse signal according to claim 1, characterized in that, Further including: Performing calibration before calculating the oil concentration in the solution to be measured, where the calibration includes: For a standard solution with a known concentration, performing the following operations: Driving the infrared LED lamp using the constant peak current to emit the pulsed infrared light; Guiding the pulsed infrared light through the measuring tube containing the standard solution; Receiving the pulsed infrared light transmitted through the standard solution and converting it into a corresponding standard solution electrical signal corresponding to each of the preset characteristic absorption wavenumbers; Processing each of the standard solution electrical signals to determine the absorbance value of the standard solution corresponding to each of the preset characteristic absorption wavenumbers; Based on the known concentration of the standard solution and its determined absorbance value, calculating the pre-calibrated coefficient and the correction factor of the pre-calibrated coefficient.

5. An infrared oil detector that drives an infrared LED lamp through a pulse signal according to claim 1, wherein The preset characteristic absorption wave numbers are 2930 , 2960 and 3030 ; The preset calculation model is as follows: ； Among them, represents the calculated oil concentration, , , are the absorbance values measured corresponding to 2930 , 2960 and 3030 wavenumbers respectively. X, Y, and Z represent the pre-calibrated coefficients corresponding to the absorbance of the target chemical bond, and F represents the correction factor of the pre-calibrated coefficient of the influence of aliphatic hydrocarbons on aromatic hydrocarbons. represents the volume of the extraction solution, represents the volume of the sample, and D represents the dilution factor of the extraction solution. represents the concentration of the blank sample.

6. The infrared oil detector that drives an infrared LED lamp through a pulse signal according to claim 1, wherein Further including: Real-time monitoring of the time variation of the absorbance value; When it is detected that at least one of the absorbance values rapidly increases beyond a preset threshold within a preset short time window, determining the relative change pattern of the absorbance values at each corresponding wavenumber during the rapid increase; Based on a preset criterion, comparing the relative change pattern with the spectral absorption characteristic pattern expected for the change in the concentration of oil substances: In response to the relative change pattern not conforming to the expected spectral absorption characteristic pattern, determining that a transient physical interference has occurred. In response to the relative change pattern conforming to the expected spectral absorption feature pattern, it is determined that the true change in oil concentration has occurred; In response to determining that a transient physical interference has occurred, perform a preset suppression or marking process on the oil concentration result calculated based on the absorbance value during the rapid increase.

7. An infrared oil detector that drives an infrared LED lamp through a pulse signal according to claim 6, characterized in that, The determining of the relative change pattern of the absorbance values at each corresponding wavenumber during the rapid increase includes: Perform Fourier transform on the first electrical signal corresponding to the wavenumber during the rapid increase to obtain a frequency spectrum including the pulse infrared light pulse frequency and its harmonics; Determine the amplitude ratio and / or relative phase relationship between the fundamental component of the pulse frequency and at least one of its harmonic components in the frequency spectrum; Compare the currently determined amplitude ratio and / or relative phase relationship with the preset reference harmonic structure parameters to generate a comparison result; Based on the comparison result, determine whether the transient physical interference has occurred.

8. An infrared oil detector that drives an infrared LED lamp through a pulse signal according to claim 3, wherein Further includes: The microcontroller cooperatively adjusts the optical path parameters and the pulse width modulation signal parameters based on the feedback signal and the differential signal: Obtain the current system state; wherein, the current system state includes at least one or a combination of multiple items among the current value of the feedback signal, the current value of the differential signal, the change rate of the feedback signal, the change rate of the differential signal, the result of determining that a transient physical interference has occurred, and the set values of the current applied optical path parameters and the pulse width modulation signal parameters; For a group of candidate cooperative adjustment amounts, use the preset state transition model to predict the future state values of one or more measurement signal indicators based on the current system state after applying each candidate cooperative adjustment amount respectively; Wherein, each of the candidate cooperative adjustment amounts includes an adjustment combination of the optical path parameters and the pulse width modulation signal parameters; Determine an optimization objective function according to the current system state and evaluate the future state values corresponding to each candidate cooperative adjustment amount; wherein, the optimization objective function aims to maximize the accuracy of oil concentration calculation; Select the candidate cooperative adjustment amount that makes the optimization objective function optimal, and control the actuator and the pulse width modulation signal based on the selected candidate cooperative adjustment amount.

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