Lubricating oil temperature dynamic monitoring device and method based on transmission spectrum

Abstract

The invention provides a transmission spectrum-based lubricating oil temperature dynamic monitoring device and method, relates to the field of non-contact lubricating oil temperature dynamic monitoring, and can realize real-time dynamic monitoring of temperature distribution of an internal space of lubricating oil in an extremely low temperature environment in a non-contact manner. According to the monitoring method, a mathematical model of temperature field distribution and light intensity characteristics is constructed by analyzing the transmittance change rule of the lubricating oil in the wavelength range of 380 nm to 1040 nm, the mathematical model is used for calculating real-time temperature distribution of the lubricating oil, the device is mainly divided into two parts, namely a spectrum acquisition module and a data processing module, and after transmission light passes through a lubricating oil medium, the real-time temperature distribution of the lubricating oil is calculated. And the optical signals are collimated through the collimating lens group, finally, the optical signals are guided into a spectrum through the receiving optical fiber, and in the data processing module, a computer is operated, and the temperature distribution of the lubricating oil is inverted according to the transmitted spectrum.

Description

Technical Field

[0001] This invention relates to the field of non-contact dynamic monitoring of lubricating oil temperature, and in particular to a device and method for dynamic monitoring of lubricating oil temperature based on transmission spectroscopy. Background Technology

[0002] In modern mechanical systems, lubricating oil plays a crucial role as a key functional material, directly impacting equipment operating efficiency, service life, and system reliability. Especially in high-performance systems such as engines, precise monitoring of lubricating oil temperature distribution is essential for optimizing lubrication efficiency and improving energy utilization efficiency. Furthermore, precise control of lubricating oil temperature is critical for oil film formation and optimizing lubrication performance. In recent years, transmission spectroscopy, as a non-contact monitoring method, has gradually become a research hotspot due to its ability to provide light intensity data without contact with the substance. Transmission spectroscopy can effectively reflect the properties of a substance.

[0003] However, traditional temperature sensors (including thermocouples, infrared thermometers, etc.) have significant limitations: slow response speed, insufficient spatial resolution, and difficulty in working stably under extreme low temperature conditions, which makes it impossible for them to achieve accurate real-time monitoring of lubricating oil temperature distribution in complex flow environments. Summary of the Invention

[0004] In response to the above situation, this invention constructs a mathematical model of temperature field distribution and light intensity characteristics by analyzing the transmittance variation law of lubricating oil in the wavelength range of 380nm to 1040nm.

[0005] The technical solution is a dynamic monitoring device for lubricating oil temperature based on transmission spectroscopy, including a spectral acquisition module and a data processing module. The spectral acquisition module acquires the transmission spectrum of lubricating oil in the 380nm to 1040nm band. The spectral acquisition module includes a halogen cold light source that emits transmitted light in the 380-1040nm wavelength band. The optical fiber transmits transmitted light to the area of ​​the lubricating oil to be tested. A focusing lens, located at the output end of the transmitting fiber, focuses the light beam to form a stable light spot; A collimating lens is used to collimate the transmitted light passing through the lubricating oil. The receiving optical fiber guides the collimated optical signal into the spectrometer. The data processing module runs on a computer and inverts the temperature distribution of lubricating oil based on transmission spectroscopy.

[0006] Furthermore, the spectral response range of both the halogen cold light source and the spectrometer is 380-1040 nm.

[0007] Furthermore, the focusing lens is directly coupled to the output end of the transmitting optical fiber, the focused spot is located in the central region of the lubricating oil container, and the spot diameter is less than 1 / 5 of the container width.

[0008] Furthermore, the collimating lens is directly coupled to the input end of the receiving optical fiber to suppress stray light and optimize beam transmission efficiency.

[0009] A method for dynamic monitoring of lubricating oil temperature based on transmission spectroscopy, S1, input lubricating oil spectral data; S2, calculate the lubricating oil transmittance based on the air and air cuvette spectra; S3, set the temperature range step size ΔT, wavelength step size ΔB, and total optical path length X; S4, segmented transmission spectrum; S5, construct and solve the determinant to invert the optical distance distribution at different temperatures; S6 outputs the optical distance of the lubricating oil at different temperatures at any given moment.

[0010] Furthermore, the formula for calculating the transmitted light intensity in step S2 is as follows: ; In the formula, The intensity of transmitted light. For the incident light intensity, For optical thickness, is the transmission constant. Optical thickness is a dimensionless quantity used to characterize the degree of light attenuation by the medium. The transmission coefficient is an important parameter of the medium, representing the proportion of light that passes through it; the value of the transmission coefficient ranges from 0 to 1. Transmittance calculation formula ; In the formula, Transmittance is the degree to which a transparent body transmits light.

[0011] Furthermore, the spectrum is decomposed into: ; ; in, for The intensity of transmitted light at a given wavelength. for Incident light intensity at a wavelength For optical thickness, for Weighted transmission constant of the optical path at wavelength, wavelength The range is arrive ; , and All of these can be measured by a spectrometer, and the expansion formulas are: ; ; in It is a wavelength of The temperature is Transmission constant at time, For temperature optical path length, This is the lowest temperature for the lubricating oil. This is the highest temperature of the lubricating oil. This refers to the temperature range step size. Will Discretize into The solution can be found by segment. : ; ; ; ; ; in The minimum wavelength of light that can pass through the lubricating oil. The maximum wavelength of light that can penetrate the lubricating oil. The wavelength step size; At this point, we have the determinant: ; ; ; In the formula, is Within the wavelength range, The average transmittance over the temperature range, Given the total length of the optical path, we obtain an m x n determinant. Calculating this formula yields the temperature along the optical path. The optical path length corresponding to the interval After arranging the temperature ranges from largest to smallest, a temperature distribution map can be drawn.

[0012] Due to the adoption of the above technical solutions, the present invention has the following advantages compared with the prior art; 1. The non-contact dynamic monitoring method and device based on transmission spectroscopy described in this invention, and the temperature field calculation method based on transmission spectroscopy analysis, can effectively solve the problems of discontinuous data acquisition and its impact on the melting process caused by the limited placement and structural characteristics of temperature sensors during the melting process of lubricating oil under extreme low temperature conditions.

[0013] 2. The non-contact dynamic monitoring method and device based on transmission spectroscopy described in this invention overcomes the technical bottleneck of infrared thermal imagers' difficulty in thermal imaging observation of low-temperature objects. By analyzing and calculating the transmission spectrum of lubricating oil, non-contact dynamic monitoring of the internal temperature field during the melting process of lubricating oil can be performed, and the temperature distribution during the melting process of lubricating oil under extreme low-temperature conditions can be more accurately grasped. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the optical path at wavelength i of the lubricating oil temperature dynamic monitoring device and method based on transmission spectroscopy according to the present invention.

[0015] Figure 2 This is a schematic diagram of the optical path length of a lubricating oil temperature dynamic monitoring device and method based on transmission spectroscopy according to the present invention.

[0016] Figure 3 This is a schematic diagram of an experiment for a dynamic monitoring device and method for lubricating oil temperature based on transmission spectroscopy according to the present invention.

[0017] Figure 4 This is a temperature change curve at a monitoring point of a lubricating oil temperature dynamic monitoring device and method based on transmission spectroscopy according to the present invention.

[0018] Figure 5 This is a transmission spectrum of lubricating oil in a device and method for dynamic monitoring of lubricating oil temperature based on transmission spectroscopy, as described in this invention.

[0019] Figure 6 This is a histogram showing the optical distance distribution at different times for a lubricating oil temperature dynamic monitoring device and method based on transmission spectroscopy according to the present invention.

[0020] Figure 7 This invention provides a comparison of temperature curves and error curves at different times for a dynamic monitoring device and method for lubricating oil temperature based on transmission spectroscopy. Figure 1 .

[0021] Figure 8 This invention provides a comparison of temperature curves and error curves at different times for a dynamic monitoring device and method for lubricating oil temperature based on transmission spectroscopy. Figure 2 .

[0022] Figure 9This is a schematic diagram of the structure of a dynamic monitoring device and method for lubricating oil temperature based on transmission spectroscopy according to the present invention.

[0023] Figure 10 This is a flowchart of the data processing module of a dynamic monitoring device and method for lubricating oil temperature based on transmission spectroscopy according to the present invention.

[0024] The components include: 1. Halogen cold light source; 2. Transmitting optical fiber; 3. Multi-channel temperature acquisition instrument; 4. Spectrometer; 5. Computer; 6. Receiving optical fiber; 7. Thermocouple connection wire; 8. Concentrating lens; 9. Heating element; 10. Transmitted light; 11. Lubricating oil; 12. Thermocouple; 13. Oil tank with optical fiber support; 14. Collimating lens; 15. Constant temperature chamber. Detailed Implementation

[0025] The foregoing and other technical contents, features and effects of the present invention are described in conjunction with the appendix below. Figures 1 to 10 The detailed description of the embodiments will make this clear. All structural details mentioned in the following embodiments are based on the accompanying drawings.

[0026] Example 1: Based on the prior art, a dynamic monitoring device for lubricating oil temperature based on transmission spectroscopy includes a spectral acquisition module and a data processing module. The spectral acquisition module acquires the transmission spectrum of lubricating oil in the 380nm to 1040nm band. The spectral acquisition module includes a halogen cold light source 1 that emits transmitted light 10 in the 380-1040nm band. Fiber 2 transmits transmitted light to the area of ​​the lubricating oil to be tested. A focusing lens 8 is located at the output end of the transmitting fiber to focus the light beam into a stable spot. Collimating lens 14 is used to collimate the transmitted light passing through the lubricating oil; Receive optical fiber 6 to guide the collimated optical signal into spectrometer 4; The data processing module runs on computer 5 and inverts the lubricating oil temperature distribution based on the transmission spectrum.

[0027] The spectral response range of both the halogen cold light source 1 and the spectrometer 4 is 380-1040 nm.

[0028] The focusing lens 8 is directly coupled to the output end of the transmitting optical fiber 2, and the focused spot is located in the central area of ​​the lubricating oil container, with the spot diameter being less than 1 / 5 of the container width.

[0029] The collimating lens 14 is directly coupled to the input end of the receiving fiber 6 to suppress stray light and optimize beam transmission efficiency.

[0030] To study the optical properties of lubricating oil at different temperatures, firstly, the visible light spectral characteristics of lubricating oil at different temperatures were tested using a spectrometer. Secondly, a preliminary analysis of the obtained visible light spectra of lubricating oil at different temperatures was conducted. The experimental data showed that the transmittance of lubricating oil at different wavelengths varied at different temperatures, and the trends of transmittance with temperature also differed. This means that a beam of light with the same intensity and spectrum will form different transmission spectra when passing through several lubricating oils with the same optical distance but different internal temperature distributions. Finally, a mathematical model between temperature distribution and light intensity was established, allowing the internal temperature distribution of the lubricating oil to be inferred from the obtained transmission spectra. This non-contact method for continuous measurement of the internal temperature of the molten liquid avoids the spatial discontinuity of data acquisition using temperature sensors and the influence of temperature sensors on the melting process, while also overcoming the limitation of infrared thermal imagers in thermal imaging observation of low-temperature objects.

[0031] Transmitted light intensity is an important physical quantity that determines the intensity and direction of light propagation through a medium. When light strikes the boundary of a medium, some of it is reflected back, while the rest passes through the medium; this is called transmitted light. The intensity of transmitted light depends on factors such as the intensity of the incident light and the properties of the medium. The following formula is used to calculate transmitted light intensity: ; In the formula, The intensity of transmitted light. For the incident light intensity, For optical thickness, is the transmission constant. Optical thickness is a dimensionless quantity used to characterize the degree of light attenuation by the medium. The transmission coefficient is an important parameter of the medium, representing the proportion of light that passes through it; the value of the transmission coefficient ranges from 0 to 1. Transmittance calculation formula ; In the formula, Transmittance is the degree to which a transparent body transmits light.

[0032] For a lubricating oil undergoing a melting process, its transmittance varies at different wavelengths due to the different states of the lubricating oil at different temperatures. Therefore, its spectrum is decomposed into: ; ; in, for The intensity of transmitted light at a given wavelength. for Incident light intensity at a wavelength For optical thickness, for Weighted transmission constant of the optical path at wavelength, wavelength The range is arrive ; , and All of these can be measured by a spectrometer, and the expansion formulas are: ; ; in It is a wavelength of The temperature is Transmission constant at time, For temperature optical path length, This is the lowest temperature for the lubricating oil. This is the highest temperature of the lubricating oil. This refers to the temperature range step size. Will Discretize into The solution can be found by segment. : ; ; ; ; ; in The minimum wavelength of light that can pass through the lubricating oil. The maximum wavelength of light that can penetrate the lubricating oil. The wavelength step size; At this point, we have the determinant: ; ; ; In the formula, is Within the wavelength range, The average transmission constant over the temperature range, Given the total length of the optical path, we obtain an m x n determinant. Calculating this formula yields the temperature along the optical path. optical path length The discretized variable x_j represents the optical path length of the j-th temperature interval [T0 + (j-1)ΔT, T0 + jΔT]. After arranging the temperature intervals from largest to smallest, a temperature distribution map can be drawn.

[0033] The specific experimental steps are as follows: 1. Insert the optical glass, light source, and collimating lens into the corresponding positions of the container, and record the transmission spectra of air and optical glass; 2. Insert the heating element into the container to heat the lubricating oil on one side; 3. Take an appropriate amount of lubricating oil and put it into a three-necked flask, and stir it at 1200 r / min for 30 minutes at a temperature of 323.15 K; 4. Take an appropriate amount of the stirred lubricating oil and pour it into the container; 5. Start the constant temperature chamber, put the container and the support into the constant temperature chamber, and insert the temperature sensor, light source, collimating lens, and heat source into the corresponding positions of the container and the support; 6. Set the relevant parameters of the constant temperature chamber to make the temperature inside the chamber drop steadily to 203.15 K and keep it at that temperature. After the temperature sensor reading stabilizes at around 203.15 K, turn on the heating element and record the temperature sensor reading and the transmission spectrum of the lubricating oil at this temperature.

[0034] A certain type of heavy-duty power transmission general-purpose lubricating oil was subjected to unilateral heating at low temperatures for 150 minutes. Ten temperature measuring points were arranged along the right side of the heating element, spaced 14 mm apart. Temperature changes and the transmission spectrum from 380 nm to 1040 nm were measured at 2-minute intervals during the 150-minute continuous heating process. Figure 4 The figure shows the temperature change curve of the monitoring point over time. Figure 5 The transmission spectra are shown at minutes 0, 30, 60, 90, 120, and 150.

[0035] The temperature range step size ∆T = 3K, the wavelength step size ∆B = 10nm, and the total optical path length X = 140mm were set. The transmission spectrum was segmented, and data processing was performed on the relevant data to obtain the determinant of the optical distance at different temperatures at each time step. Solving the determinant yielded the distribution of optical distance at different temperatures at each time step. The histograms of the optical distance distribution at different temperatures at minutes 0, 30, 60, 90, 120, and 150 are shown below. Figure 6 As shown.

[0036] Because lubricating oil melts in a unidirectional manner at low temperatures, its temperature exhibits a monotonically increasing or decreasing distribution. Figure 6 Comparison of the temperature distribution curve obtained after arranging the optical distance according to the descent point with the temperature distribution curve and error curve measured by the sensor, for example. Figure 7 , Figure 8As shown, the error between the calculated and experimental values ​​was small in the initial heating stage, with an average error of only 0.64% and a maximum error of only 1.46% across the ten monitoring points. As the heating time increased, the error between the calculated and experimental values ​​also increased, reaching its maximum at 60 minutes of heating, at which point the average error across the ten monitoring points was 2.17%, and the maximum error was 5.18%. After this point, the error between the calculated and experimental values ​​tended to stabilize until the end of the heating period. The average errors at 90 minutes, 120 minutes, and 150 minutes were 1.43%, 1.50%, and 1.25%, respectively, with maximum errors of 3.06%, 2.09%, and 2.24%, respectively.

[0037] The above description is a further detailed explanation of the present invention in conjunction with specific embodiments, and it should not be considered that the specific implementation of the present invention is limited to this. For those skilled in the art to which the present invention pertains and related fields, any extensions, operation methods, and data substitutions made based on the technical solution concept of the present invention should fall within the protection scope of the present invention.

Claims

1. A dynamic monitoring device for lubricating oil temperature based on transmission spectroscopy, characterized in that, It includes a spectral acquisition module and a data processing module. The spectral acquisition module acquires the transmission spectrum of the lubricating oil in the 380nm to 1040nm wavelength range. The spectral acquisition module includes a halogen cold light source (1) that emits transmitted light (10) in the 380-1040nm band. The transmitting optical fiber (2) transmits transmitted light to the area of ​​the lubricating oil to be tested; A focusing lens (8) is located at the output end of the transmitting fiber to focus the beam into a stable spot. Collimating lens (14) is used to collimate the transmitted light passing through the lubricating oil; The receiving optical fiber (6) guides the collimated optical signal into the spectrometer (4). The data processing module runs on the computer (5) and inverts the temperature distribution of lubricating oil based on the transmission spectrum.

2. The lubricating oil temperature dynamic monitoring device based on transmission spectroscopy as described in claim 1, characterized in that, The spectral response range of the halogen cold light source (1) and the spectrometer (4) is 380-1040nm.

3. The lubricating oil temperature dynamic monitoring device based on transmission spectroscopy as described in claim 1, characterized in that, The focusing lens (8) is directly coupled to the output end of the transmitting optical fiber (2), and the focused spot is located in the central area of ​​the lubricating oil container, and the diameter of the spot is less than 1 / 5 of the container width.

4. The lubricating oil temperature dynamic monitoring device based on transmission spectroscopy as described in claim 1, characterized in that, The collimating lens (14) is directly coupled to the input end of the receiving fiber (6) to suppress stray light and optimize beam transmission efficiency.

5. A method for dynamic monitoring of lubricating oil temperature based on transmission spectroscopy, applied to the device described in any one of claims 1-4, characterized in that, S1, Input lubricating oil spectral data; S2, calculate the lubricating oil transmittance based on the air and air cuvette spectra; S3, set the temperature range step size ΔT, wavelength step size ΔB, and total optical path length X; S4, segmented transmission spectrum; S5, construct and solve the determinant to invert the optical distance distribution at different temperatures; S6 outputs the optical distance of the lubricating oil at different temperatures at any given moment.

6. The method for dynamic monitoring of lubricating oil temperature based on transmission spectroscopy as described in claim 5, characterized in that, The formula for calculating transmitted light intensity in step S2 is as follows: ； In the formula, The intensity of transmitted light. For the incident light intensity, For optical thickness, is the transmission constant, where optical thickness is a dimensionless quantity used to characterize the degree of light attenuation by the medium. The transmission coefficient is an important parameter of the medium, which represents the proportion of light that passes through the medium. The value of the transmission coefficient ranges from 0 to 1. Transmittance calculation formula ； In the formula, Transmittance is the degree to which a transparent body transmits light.

7. The method for dynamic monitoring of lubricating oil temperature based on transmission spectroscopy as described in claim 6, characterized in that, Spectral decomposition is as follows: ； ； in, for The intensity of transmitted light at a given wavelength. for Incident light intensity at a wavelength For optical thickness, for Weighted transmission constant of the optical path at wavelength, wavelength The range is arrive ; , and All of these can be measured by a spectrometer, and the expansion formulas are: ； ； in It is a wavelength of The temperature is Transmission constant at time, For temperature optical path length, This is the lowest temperature for the lubricating oil. This is the highest temperature of the lubricating oil. This refers to the temperature range step size. Will Discretize into The solution can be found by segment. : ； ； ； ； ； in The minimum wavelength of light that can pass through the lubricating oil. The maximum wavelength of light that can penetrate the lubricating oil. The wavelength step size; At this point, we have the determinant: ； ； ； In the formula for Within the wavelength range, The average transmittance over the temperature range, Given the total length of the optical path, we obtain an m x n determinant. Calculating this formula yields the temperature along the optical path. The optical path length corresponding to the interval After arranging the temperature ranges from largest to smallest, a temperature distribution map can be drawn.

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