Fluid lubrication pressure and temperature monitoring method and quantum dot sensor

Abstract

The invention discloses a fluid lubrication pressure and temperature monitoring method and a quantum dot sensor, and belongs to the technical field of fluid lubrication state monitoring. The method comprises the following steps: uniformly dispersing perovskite quantum dots in basic lubricating oil to prepare quantum dot lubricating oil, and introducing the quantum dot lubricating oil into a lubricating system to be monitored; in the running process of the lubricating system, quantum dots in lubricating oil are excited, and fluorescence spectrum signals of the quantum dots are collected in real time; extracting fluorescence peak wavelength and fluorescence intensity; converting the acquired fluorescence information into pressure information and temperature information according to a pre-established pressure-peak position calibration relation and a pre-established temperature-intensity calibration relation; fluorescence signals of the contact area and the non-contact area are distinguished through the time dimension or the space dimension, and in-situ distinguishing monitoring of the pressure and the temperature in the lubricating system is achieved. According to the invention, two-parameter in-situ differentiated measurement of pressure and temperature in the same lubricating fluid is realized, and interference of traditional contact measurement on a lubricating flow field is avoided.

Description

Technical Field

[0001] This invention relates to the field of fluid lubrication condition monitoring technology, specifically to a method for monitoring fluid lubrication pressure and temperature and a quantum dot sensor. Background Technology

[0002] During the operation of mechanical equipment, the lubrication condition directly affects the system's reliability, energy efficiency, and service life. Especially in critical friction pairs such as rolling bearings, gear pairs, and sliding bearings, the pressure and temperature of the lubricating oil film are key parameters determining the oil film's load-bearing capacity, viscosity changes, and tribological state. Real-time and accurate monitoring of the internal pressure and temperature of the lubricating oil film is of great significance for achieving equipment health management and predictive maintenance.

[0003] Currently, the monitoring of lubricating oil film pressure and temperature mainly relies on contact sensing methods such as thermocouples, strain gauges, and piezoelectric sensors. These sensors typically need to be embedded or attached inside the mechanical structure, which not only involves complex installation and difficult wiring, but also alters the original lubrication structure and flow field distribution to some extent, interfering with the actual working state of the lubrication interface. Furthermore, due to limitations in space, working environment, and signal extraction methods, these methods are difficult to implement in-situ measurement of the internal pressure and temperature of the lubricating oil film, especially limiting their application in high-speed, enclosed lubrication systems.

[0004] In recent years, quantum dot-based optical sensing technology has gained increasing attention in monitoring complex and confined environments due to its non-contact measurement, remote signal readout, and good resistance to electromagnetic interference. Quantum dot materials exhibit sensitive fluorescence response to external physical stimuli (such as temperature and pressure), offering possibilities for developing novel optical sensing methods. However, current research on introducing quantum dots into lubricating oil systems mainly focuses on their friction reduction, wear resistance, or lubrication performance improvement. Furthermore, under actual lubrication conditions, pressure and temperature often act simultaneously on the luminescent material, resulting in a significant coupling effect on the fluorescence signal. This makes it difficult for a single optical signal to directly distinguish the contributions of different physical fields, further increasing the difficulty of multi-parameter identification and quantitative characterization. Therefore, how to effectively distinguish pressure and temperature signals in fluid lubrication media remains a pressing problem for current optical lubrication condition monitoring technology. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems in the prior art and provide a method for monitoring fluid lubrication pressure and temperature, as well as a quantum dot sensor, which can effectively distinguish between pressure and temperature signals in fluid lubrication media.

[0006] This invention provides a method for monitoring fluid lubrication pressure and temperature, comprising the following steps: Perovskite quantum dots are uniformly dispersed in a base lubricating oil to prepare a quantum dot lubricating oil, which is then introduced into the lubrication system to be monitored. During the operation of the lubrication system, quantum dots in the lubricating oil are excited, and the fluorescence spectrum signal of the quantum dots is collected in real time. Two characteristic parameters, fluorescence peak wavelength and fluorescence intensity, are extracted from the collected fluorescence spectral signals. Based on the pre-established pressure-peak position calibration relationship, the fluorescence peak wavelength collected in the contact area is converted into pressure information of the lubrication contact area. Based on the pre-established temperature-intensity calibration relationship, the fluorescence intensity collected in the non-contact area is converted into temperature information of the lubricating oil film. By distinguishing the fluorescence signals of the contact area and the non-contact area through time or space dimensions, in-situ differential monitoring of pressure and temperature in the lubrication system is achieved.

[0007] Preferably, the contact area is the region in the lubrication system where the moving parts and mating surfaces periodically form load-bearing contact; the non-contact area is the region in the lubrication system where the moving parts do not form load-bearing contact. During the monitoring process, the acquisition time of the fluorescence signal is synchronized with the motion cycle of the lubrication system: when the acquisition time corresponds to the time window when the moving part is in the contact area, it is determined that the acquired fluorescence signal originates from the contact area, and its fluorescence peak wavelength is extracted to obtain pressure information; when the acquisition time corresponds to the time window when the moving part leaves the contact area, it is determined that the acquired fluorescence signal originates from the non-contact area, and its fluorescence intensity is extracted to obtain temperature information; by adjusting the signal acquisition frequency and combining it with the motion cycle parameters of the lubrication system, time-division monitoring of pressure and temperature is achieved.

[0008] Preferably, the pressure-peak calibration relationship is established by applying different known pressures to the quantum dot lubricating oil under constant temperature conditions, measuring the fluorescence peak wavelength corresponding to each pressure point, and fitting the linear relationship between pressure and fluorescence peak wavelength.

[0009] Preferably, the temperature-intensity calibration relationship is established by placing the quantum dot lubricating oil in different known temperature environments under no external pressure, measuring the fluorescence intensity corresponding to each temperature point, and fitting the linear relationship between temperature and fluorescence intensity.

[0010] Preferably, the perovskite quantum dots are CsPbBr3 quantum dots.

[0011] The present invention also provides a quantum sensor employing the above-described fluid lubrication pressure and temperature monitoring method, comprising: Quantum dot lubricant, comprising base lubricant and perovskite quantum dots uniformly dispersed therein, wherein during the operation of the lubrication system, the perovskite quantum dots periodically enter the lubrication contact area and non-contact area along with the lubricant; An excitation light source, located outside the lubrication system, is used to provide excitation light to the perovskite quantum dots in the lubricating oil, causing them to generate fluorescence signals; A spectral acquisition device, located outside the lubrication system, is used to acquire in real time the fluorescence spectral signal generated by perovskite quantum dots under the action of excitation light; The signal processing module, connected to the spectral acquisition device, is used to extract feature parameters from the acquired fluorescence spectral signals and obtain the pressure and temperature information of the lubrication system based on the feature parameters. A timing control unit, connected to the spectral acquisition device, is used to control the acquisition timing of the spectral acquisition device according to the motion cycle of the lubrication system, so that the spectral acquisition device acquires fluorescence signals for pressure monitoring in the contact area and fluorescence signals for temperature monitoring in the non-contact area.

[0012] Preferably, the signal processing module includes a storage unit for storing pre-established pressure-peak calibration relationships and temperature-intensity calibration relationships; and a calculation unit for substituting the collected fluorescence peak wavelength into the pressure-peak calibration relationship to calculate the pressure value, and substituting the collected fluorescence intensity into the temperature-intensity calibration relationship to calculate the temperature value.

[0013] Preferably, the lubrication system is a rolling bearing, a sliding bearing, or a gear pair.

[0014] Compared with the prior art, the beneficial effects of the present invention are: This invention utilizes the differential response characteristics of perovskite quantum dots, such as fluorescence peak position shift under pressure and fluorescence intensity change under temperature. By extracting two independent characteristic parameters, peak wavelength and intensity, from the fluorescence spectrum and combining them with the motion cycle of the lubrication system for time-division acquisition, it effectively solves the signal aliasing problem caused by multi-physics coupling and realizes in-situ distinguishable measurement of pressure and temperature under the same optical probe in the same lubricating fluid. This invention directly incorporates quantum dots into lubricating oil, serving as both a sensing unit and a lubricating additive. The excitation light source and spectral acquisition device in this invention are both located outside the lubrication system, eliminating the need to embed any sensors in the mechanical structure. This avoids interference from traditional contact measurements on the lubrication flow field and accurately reflects the working state inside the lubricating oil film.

[0015] This invention is based on the principle of optical sensing, enabling fast signal acquisition and processing, and adapting to complex lubrication conditions such as high speed and high load. By adjusting the signal acquisition frequency and synchronizing it with the motion cycle of the lubrication system, dynamic monitoring can be achieved in periodically contacting friction pairs such as rolling bearings and gear pairs. Attached Figure Description

[0016] Figure 1 This is a graph showing the fluorescence response characteristics of quantum dots under pressure according to an embodiment of the present invention.

[0017] Figure 2 This is a graph showing the fluorescence response characteristics of quantum dots under temperature in an embodiment of the present invention.

[0018] Figure 3 This is a schematic diagram illustrating the working principle of the quantum dot sensor in a lubrication system according to an embodiment of the present invention.

[0019] Figure 4 This is a schematic diagram illustrating the working process of the quantum dot sensor in the lubrication system according to an embodiment of the present invention.

[0020] Figure 5 This is a curve comparing the friction coefficients of the original lubricating oil and the quantum dot lubricating oil in an embodiment of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0022] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms “first,” “second,” and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as “comprising” or “including” indicate that the elements or objects preceding “comprising” or “including” encompass the elements or objects listed following “comprising” or “including” and their equivalents, and do not exclude other elements or objects. Terms such as “connected” or “linked” are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as “upper,” “lower,” “left,” and “right” are used only to indicate relative positional relationships; when the absolute position of the described objects changes, the relative positional relationship may also change accordingly.

[0023] This invention discloses a method for monitoring fluid lubrication pressure and temperature, comprising the following steps: Quantum dot lubricating oil is prepared by uniformly dispersing perovskite quantum dots in a base lubricating oil; the quantum dot lubricating oil is then introduced into the fluid lubrication system to be monitored. During the operation of the lubrication system, quantum dots in the lubricating oil are excited, and the fluorescence spectrum signal of the quantum dots is collected in real time. Two characteristic parameters, fluorescence peak wavelength and fluorescence intensity, are extracted from the collected fluorescence spectral signals. Based on the pre-established pressure-peak position calibration relationship, the fluorescence peak wavelength collected in the contact area is converted into pressure information of the lubrication contact area. Based on the pre-established temperature-intensity calibration relationship, the fluorescence intensity collected in the non-contact area is converted into temperature information of the lubricating oil film. By distinguishing the fluorescence signals of the contact area and the non-contact area through time or space dimensions, in-situ differential monitoring of pressure and temperature in the fluid lubrication system is achieved.

[0024] In this embodiment, the quantum dot lubricating oil can be prepared using conventional methods in the art, such as hot injection or solvothermal methods, and the specific preparation method does not constitute a limitation of this invention. As another preferred embodiment, to improve the dispersion stability and optical response consistency of quantum dots in the lubricating oil, the quantum dots can be surface modified, for example, by introducing long-chain strong ligands to enhance their compatibility with the lubricating oil, or by using polymer coating or constructing a core-shell structure to form a steric hindrance protective layer, thereby inhibiting particle aggregation and sedimentation and improving the stability of the fluorescence response. The above modification methods are not limited to the specific forms listed. The optimized quantum dots are dispersed in the base lubricating oil according to a predetermined mass fraction, and the quantum dots are uniformly dispersed in the lubricating oil by ultrasound or stirring to form a stable quantum dot lubricating oil. As another preferred embodiment, a dispersant can be added to the quantum dot lubricating oil to further enhance the system stability, and the quantum dot lubricating oil is prepared by ultrasonic dispersion and high-shear mixing processes, thereby avoiding inconsistent fluorescence responses caused by quantum dot sedimentation or aggregation.

[0025] In this embodiment, before conducting in-situ monitoring of the lubrication system, the fluorescence response characteristics of the quantum dots under pressure were first calibrated. Specifically, a lubricating oil sample containing perovskite quantum dots was placed in a high-pressure loading device. Under constant ambient temperature conditions, known pressures of varying magnitudes were applied in stages to bring the quantum dots into a uniformly pressurized state. Under each pressure loading state, the quantum dots were excited using an excitation light source, and their fluorescence emission spectra were acquired using a spectral acquisition device, recording the corresponding fluorescence peak wavelengths.

[0026] By fitting and analyzing the changes in fluorescence peak positions under different pressure conditions, a correspondence between fluorescence peak wavelength and pressure was established, preferably a linear calibration relationship. Figure 1 As shown. The calibration relationship can be expressed as: P = a·λ + b; where P is the pressure value, λ is the fluorescence peak position, and a and b are coefficients determined through calibration experiments.

[0027] To facilitate understanding, the pressure calibration process described above will be explained below with reference to specific implementation methods.

[0028] In one specific embodiment, pressure calibration can be performed using a high-pressure loading device. This pressurizing device preferably includes a pair of opposing diamond anvils, a metal gasket, and pressure calibration particles. The sample and the pressure calibration particles are placed together in a sample cavity formed by the diamond anvils and the hollow gasket. During pressurization, different levels of static pressure are applied to the sample by progressively adjusting the spacing between the diamond anvils. The pressure values ​​can be calibrated using pressure calibration methods known in the art, such as pressure calibration methods based on ruby ​​fluorescence peak position drift.

[0029] Under different pressure conditions, the sample is optically excited and its fluorescence spectrum signal is collected. The relationship between the fluorescence emission peak position of quantum dots and pressure is recorded, thereby obtaining the calibration curve between the fluorescence peak position and pressure.

[0030] It should be noted that the pressurization method and pressure calibration method described above are only one exemplary implementation. The present invention is not limited to the use of diamond anvil or ruby ​​calibration methods. Any device or method that can achieve known pressure loading and complete pressure calibration can be used to establish the calibration relationship.

[0031] This embodiment calibrates the relationship between quantum dot fluorescence intensity and temperature without applying external mechanical pressure.

[0032] The quantum dot lubricant sample was placed in a temperature-controlled environment and kept stable for a period of time under different set temperature conditions to allow the quantum dots to reach thermal equilibrium. Subsequently, at each temperature point, the fluorescence spectrum signal of the quantum dots was collected using the same excitation conditions, and the corresponding fluorescence intensity parameters were extracted.

[0033] By analyzing the variation of fluorescence intensity with temperature, a calibration relationship between fluorescence intensity and temperature is established, such as... Figure 2 As shown. The relationship is preferably an approximately linear relationship, which can be expressed as: T = c·I + d; where T is the temperature value, I is the fluorescence intensity, and c and d are calibration coefficients.

[0034] In another specific embodiment, temperature calibration can be performed in a temperature-controlled spectral testing system. Different set temperatures are applied to the quantum dot lubricating oil sample using a temperature control device, and the temperature is maintained stable at each point until the sample reaches thermal equilibrium. Under different temperature conditions, the quantum dots are optically excited, and their fluorescence spectral signals are collected. The corresponding fluorescence intensity parameters are extracted, and a correlation between fluorescence intensity and temperature is established.

[0035] The above-mentioned temperature-controlled spectral testing system may include a temperature control unit, a temperature sensor, and a spectral acquisition device. However, the present invention does not limit the specific configuration of the system. Any device that can achieve temperature control and complete fluorescence signal acquisition is applicable to the present invention.

[0036] After completing the pressure and temperature calibration, the quantum dot lubricating oil is introduced into the fluid lubrication system to be monitored. During the operation of the lubrication system, the quantum dots in the lubrication interface or lubricating oil film are excited in situ using an excitation light source and optical fiber arranged outside the system, and their fluorescence signals are collected in real time.

[0037] When the lubrication interface is under load or in contact, the quantum dots in the lubricating oil film are subjected to local contact pressure, causing a shift in their fluorescence emission peak position. At this time, based on a pre-established pressure calibration relationship, the collected fluorescence peak position parameters are converted into corresponding pressure information.

[0038] When the lubrication interface is in an unloaded or non-contact state, the quantum dots are basically unaffected by mechanical pressure, their fluorescence emission peak position remains stable, and their fluorescence intensity mainly changes with temperature. At this time, according to the temperature calibration relationship, the collected fluorescence intensity parameters are converted into temperature information of the lubricating oil film.

[0039] In another preferred embodiment, the contact area is the region in the lubrication system where the moving parts and mating surfaces periodically form load-bearing contact; the non-contact area is the region in the lubrication system where the moving parts do not form load-bearing contact. During the monitoring process, the acquisition time of the fluorescence signal is synchronized with the motion cycle of the lubrication system: when the acquisition time corresponds to the time window when the moving part is in the contact area, it is determined that the acquired fluorescence signal originates from the contact area, and its fluorescence peak wavelength is extracted to obtain pressure information; when the acquisition time corresponds to the time window when the moving part leaves the contact area, it is determined that the acquired fluorescence signal originates from the non-contact area, and its fluorescence intensity is extracted to obtain temperature information; by adjusting the signal acquisition frequency and combining it with the motion cycle parameters of the lubrication system, time-division monitoring of pressure and temperature is achieved.

[0040] This embodiment combines the operating parameters or relative motion cycle of the lubrication system to distinguish the fluorescence signals of the pressurized and non-pressurized stages in terms of time or space, thereby achieving in-situ monitoring of pressure and temperature in the lubrication system. The distinction between the contact area and the non-contact area is determined based on the structural characteristics and operating parameters of the lubrication system. Taking a lubrication system with periodic contact motion as an example, the loaded and unloaded periods of the lubrication interface within one motion cycle can be predetermined based on the geometry, rotational speed, and motion cycle of the relatively moving parts.

[0041] In the actual monitoring process, the acquisition time of the fluorescence signal is synchronized with the motion cycle. When the acquisition time corresponds to the loaded period, it is determined that the acquired fluorescence signal comes from the lubrication contact area; when the acquisition time corresponds to the unloaded period, it is determined that the acquired fluorescence signal comes from the non-contact lubrication area.

[0042] After completing the above calibration, quantum dot lubricating oil was introduced into the rolling bearing lubrication system. During bearing operation, the quantum dots in the lubricating oil film were excited in situ using an external excitation light source and optical fiber, and their fluorescence signals were collected in real time.

[0043] To improve the accuracy of calibration relationships and monitoring results, the following operating conditions are preferred: (1) During calibration and actual monitoring, keep the excitation power, excitation wavelength and optical path arrangement conditions consistent to reduce the impact of changes in the optical system on the fluorescence signal; (2) The dispersion state of quantum dots in lubricating oil remains stable, avoiding inconsistent fluorescence response due to sedimentation or agglomeration; (3) For calibration and actual monitoring, it is preferable to use quantum dot lubricating oil from the same batch or with the same preparation process to ensure the consistency of the quantum dot system.

[0044] It should be noted that the pressure and temperature applied during the calibration process are known physical quantities under controllable conditions. However, the pressure and temperature in actual lubrication conditions are usually generated by a combination of factors such as mechanical contact, load transfer, and frictional heat generation, and the loading methods may differ. Nevertheless, the quantum dot fluorescence response utilized in this invention is an intrinsic physical property of the material; its fluorescence peak position responds to pressure changes, and its fluorescence intensity responds to temperature changes, regardless of the specific application of the macroscopic load. Therefore, as long as the quantum dot system, excitation conditions, and signal acquisition method remain consistent with the calibration stage, the established calibration relationship can be used to characterize the local pressure and temperature under actual lubrication conditions.

[0045] The following description uses a rolling bearing, a typical fluid lubrication system, to illustrate the specific application of the quantum dot sensor and its in-situ monitoring method of this invention. It should be noted that this embodiment is only used to illustrate a preferred application of the invention in a rolling bearing and does not constitute a limitation on the scope of the invention.

[0046] Please see Figure 3 , Figure 3 This diagram illustrates the working principle of the quantum dot sensor of the present invention in a lubrication system. The mechanical lubrication system of the present invention uses a rolling bearing as an example, including an outer ring, an inner ring, and multiple rolling elements disposed therebetween. A rolling contact area is formed between the inner and outer rings. During bearing operation, the rolling elements periodically enter and leave the contact area, thereby forming a loaded area and an unloaded area in the lubricating oil film.

[0047] The lubrication system of this embodiment is filled with a lubricating oil doped with quantum dots. The lubricating oil contains uniformly dispersed perovskite quantum dots, preferably surface-modified CsPbBr3 quantum dots. These quantum dots serve both as a lubricating additive and as an optical sensing unit for in-situ sensing of the lubrication state. Furthermore, this embodiment uses CsPbBr3 perovskite quantum dots as the fluorescence sensing unit, which possesses advantages such as high thermal stability, good optical stability, narrow emission peak, high sensitivity to pressure-induced peak shift, and significant temperature-induced modulation of fluorescence intensity. This facilitates in-situ distinguishable measurement of both pressure and temperature.

[0048] The optical system described in this embodiment includes: Excitation light source: used to provide excitation light to quantum dots in lubricating oil; Optical fiber: used to introduce excitation light and collect fluorescence signals; Spectrometer: Connected to optical fiber, used for spectral analysis of acquired fluorescence signals; Signal processing module: used for analyzing and calculating fluorescence peak positions and fluorescence intensities.

[0049] And a timing control unit, connected to the spectral acquisition device, is used to control the acquisition timing of the spectral acquisition device according to the motion cycle of the lubrication system, so that the spectral acquisition device acquires fluorescence signals for pressure monitoring in the contact area and fluorescence signals for temperature monitoring in the non-contact area.

[0050] More specifically, the signal processing module of this embodiment includes: a storage unit for storing pre-established pressure-peak position calibration relationship and temperature-intensity calibration relationship; and a calculation unit for substituting the collected fluorescence peak wavelength into the pressure-peak position calibration relationship to calculate the pressure value, and substituting the collected fluorescence intensity into the temperature-intensity calibration relationship to calculate the temperature value.

[0051] There is no direct mechanical contact between the optical system and the lubrication system, enabling non-invasive measurement.

[0052] This invention utilizes the different fluorescence response mechanisms exhibited by quantum dots under different physical fields: When quantum dots enter the lubrication contact area with lubricating oil, they are subjected to local contact pressure, causing slight compression of their crystal lattice and resulting in changes in their band structure. This manifests as a linear shift in the fluorescence emission peak position with pressure changes, such as... Figure 1 As shown.

[0053] When quantum dots are in the non-contact lubrication region, they experience almost no mechanical pressure, and their fluorescence emission peak position remains essentially unchanged. At this point, the fluorescence intensity of the quantum dots is mainly affected by temperature, exhibiting a repeatable and nearly linear relationship with temperature changes. Figure 2 As shown.

[0054] In the specific application scenario of rolling bearings, the contact area and non-contact area can be determined based on the bearing's geometry and operating parameters. For a given rolling bearing structure, it typically contains multiple rolling elements. These rolling elements are distributed circumferentially along the raceway during bearing rotation and periodically enter and leave the raceway contact area according to a defined motion law, thus forming recurring contact events in space and time.

[0055] During bearing operation, the time intervals for each rolling element to enter and leave the raceway contact area can be predetermined based on the bearing speed, the number of rolling elements, and their motion cycle.

[0056] For shaft speed of The pitch circle diameter is The diameter of the rolling element is Contact angle is The rolling bearing, whose rolling elements have a revolution frequency It can be represented as: Duration of a single contact According to the circumferential angle of the contact area (Determined by the width of the Hertzian contact area) Calculated as follows: This allows us to determine the contact time interval corresponding to the fluorescence signal.

[0057] Since the contact events of multiple rolling elements exhibit a periodic distribution over time, the acquisition of fluorescence signals can be considered as a comprehensive response to one or more rolling element contact events within the stated time interval. When the acquisition time of the fluorescence signal corresponds to the time interval in which the rolling element is located within the contact area, the acquired fluorescence signal is determined to originate from the lubricated contact area; when the acquisition time corresponds to the time interval in which the rolling element leaves the contact area, the acquired fluorescence signal is determined to originate from the non-contact lubrication area.

[0058] During the operation of a rolling bearing, the rolling elements periodically enter and leave the contact zone, causing the lubricating oil film to alternately be in a loaded and unloaded state over time. When the rolling element passes through the contact zone, the peak position of the collected fluorescence signal shifts significantly, which can be used to invert the local contact pressure. When the rolling element leaves the contact zone, the peak position of the fluorescence signal remains relatively stable, and its fluorescence intensity change can be used to characterize the temperature of the lubricating oil film. By adjusting the signal acquisition frequency and combining it with operating parameters such as bearing speed and the number of rolling elements, the pressure response stage and the temperature response stage can be distinguished over time, thus achieving pressure and temperature differential monitoring based on a single quantum dot system.

[0059] Combination Figure 4 The test process diagram shown illustrates the following steps in implementing this invention in rolling bearings: (1) Preparation of quantum dot lubricating oil: Surface-modified perovskite quantum dots are dispersed in base lubricating oil at a predetermined mass fraction to form a stable and uniform quantum dot lubricating oil; (2) Introduction of quantum dot lubricant: The quantum dot lubricant is introduced into the lubrication system, and a continuous lubricating oil film is formed on the surface of the friction pair during the operation of the system. The lubricating oil film periodically enters the contact area and the non-contact area with the movement of the friction pair.

[0060] (3) Optical excitation and signal acquisition setup: An excitation source, optical fiber and spectrometer are arranged outside the lubrication system so that the excitation light is irradiated to the area where the lubricating oil film is located through the optical fiber, and the fluorescence signal emitted by the quantum dot is collected through the same or another optical fiber.

[0061] (4) Differentiation and acquisition of fluorescence signals: During the operation of the bearing, fluorescence signals corresponding to the contact area and non-contact area are collected according to the contact state of the lubricating oil film, and fluorescence peak position parameters and fluorescence intensity parameters are extracted.

[0062] (5) Parameter differentiation and lubrication status monitoring: Based on the pre-established calibration relationship, the fluorescence peak position change in the contact area is converted into pressure information of the lubrication interface, and the fluorescence intensity change in the non-contact area is converted into lubricating oil film temperature information, thereby realizing in-situ monitoring of the lubrication status of the rolling bearing.

[0063] To verify that the addition of quantum dots does not damage the tribological properties of the base lubricating oil and has an improving effect on lubrication performance, this embodiment compares the tribological properties of the quantum doped lubricating oil with those of the original lubricating oil.

[0064] The friction performance test was conducted using a tribological testing machine. The friction pair adopted a ball-disc structure, where both the ball and the disk were made of GCr15 bearing steel. The steel ball had a diameter of 6 mm, and the surface of the disk was mechanically polished to a surface roughness Ra of 0.1 μm.

[0065] Before each friction test, the steel ball and disk samples were placed in anhydrous ethanol and cleaned under ultrasonic conditions for 15 minutes to remove surface contaminants, and then allowed to air dry.

[0066] The friction test was conducted at room temperature, with a normal load of 15 N, a friction radius of 10 mm, a rotational speed of 100 rpm, and a test duration of 3600 s. During the friction process, the friction coefficient was automatically recorded in real time by the testing machine at a sampling frequency of 1 Hz.

[0067] The test samples included raw lubricating oil and quantum dot-doped smart lubricating oil. The smart lubricating oil was prepared as follows: under magnetic stirring, 0.5 mL of a 10 mg·mL⁻¹ quantum dot solution was slowly added dropwise to 9.995 g of base lubricating oil to prepare a 0.05 wt% quantum dot lubricating oil sample. After mixing, the quantum dot solvent was removed by rotary evaporation at 50 °C to obtain a smart lubricating oil with uniformly dispersed quantum dots.

[0068] Test results are as follows Figure 5 As shown, where Figure 5 The figures show the coefficient of friction versus time for the original lubricating oil and the lubricating oil with 0.05 wt% quantum dots under the same friction conditions. The results indicate that, compared to the original lubricating oil, the quantum dot-doped lubricating oil exhibits a lower and more stable coefficient of friction during friction, suggesting that the addition of quantum dots does not impair the tribological properties of the lubricating oil and even improves its lubrication performance to some extent.

[0069] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for monitoring fluid lubrication pressure and temperature, characterized in that, Includes the following steps: Perovskite quantum dots are uniformly dispersed in a base lubricating oil to prepare a quantum dot lubricating oil, which is then introduced into the lubrication system to be monitored. During the operation of the lubrication system, quantum dots in the lubricating oil are excited, and the fluorescence spectrum signal of the quantum dots is collected in real time. Two characteristic parameters, fluorescence peak wavelength and fluorescence intensity, are extracted from the collected fluorescence spectral signals. Based on the pre-established pressure-peak position calibration relationship, the fluorescence peak wavelength collected in the contact area is converted into pressure information of the lubrication contact area. Based on the pre-established temperature-intensity calibration relationship, the fluorescence intensity collected in the non-contact area is converted into temperature information of the lubricating oil film. By distinguishing the fluorescence signals of the contact area and the non-contact area through time or space dimensions, in-situ differential monitoring of pressure and temperature in the lubrication system is achieved.

2. The method for monitoring fluid lubrication pressure and temperature as described in claim 1, characterized in that, The contact area is the region in the lubrication system where moving parts and mating surfaces periodically form load-bearing contact; the non-contact area is the region in the lubrication system where moving parts do not form load-bearing contact. During the monitoring process, the acquisition time of the fluorescence signal is synchronized with the motion cycle of the lubrication system: when the acquisition time corresponds to the time window when the moving part is in the contact area, it is determined that the acquired fluorescence signal originates from the contact area, and its fluorescence peak wavelength is extracted to obtain pressure information; when the acquisition time corresponds to the time window when the moving part leaves the contact area, it is determined that the acquired fluorescence signal originates from the non-contact area, and its fluorescence intensity is extracted to obtain temperature information; by adjusting the signal acquisition frequency and combining it with the motion cycle parameters of the lubrication system, time-division monitoring of pressure and temperature is achieved.

3. The method for monitoring fluid lubrication pressure and temperature as described in claim 1, characterized in that, The pressure-peak calibration relationship is established as follows: under constant temperature conditions, different known pressures are applied to the quantum dot lubricating oil, the fluorescence peak wavelengths corresponding to each pressure point are measured, and the linear relationship between pressure and fluorescence peak wavelengths is obtained by fitting.

4. The method for monitoring fluid lubrication pressure and temperature as described in claim 1, characterized in that, The temperature-intensity calibration relationship is established as follows: under no external pressure, the quantum dot lubricant is placed in different known temperature environments, the fluorescence intensity at each temperature point is measured, and the linear relationship between temperature and fluorescence intensity is obtained by fitting.

5. The method for monitoring fluid lubrication pressure and temperature as described in claim 1, characterized in that, The perovskite quantum dots are CsPbBr3 quantum dots.

6. A quantum sensor employing the fluid lubrication pressure and temperature monitoring method according to any one of claims 1-5, characterized in that, include: Quantum dot lubricant, comprising base lubricant and perovskite quantum dots uniformly dispersed therein, wherein during the operation of the lubrication system, the perovskite quantum dots periodically enter the lubrication contact area and non-contact area along with the lubricant; An excitation light source, located outside the lubrication system, is used to provide excitation light to the perovskite quantum dots in the lubricating oil, causing them to generate fluorescence signals; A spectral acquisition device, located outside the lubrication system, is used to acquire in real time the fluorescence spectral signal generated by perovskite quantum dots under the action of excitation light; The signal processing module, connected to the spectral acquisition device, is used to extract feature parameters from the acquired fluorescence spectral signals and obtain the pressure and temperature information of the lubrication system based on the feature parameters. A timing control unit, connected to the spectral acquisition device, is used to control the acquisition timing of the spectral acquisition device according to the motion cycle of the lubrication system, so that the spectral acquisition device acquires fluorescence signals for pressure monitoring in the contact area and fluorescence signals for temperature monitoring in the non-contact area.

7. The quantum sensor as described in claim 6, characterized in that, The signal processing module includes: Storage units are used to store pre-established pressure-peak calibration relationships and temperature-intensity calibration relationships; The calculation unit is used to calculate the pressure value by substituting the collected fluorescence peak wavelength into the pressure-peak position calibration relationship, and to calculate the temperature value by substituting the collected fluorescence intensity into the temperature-intensity calibration relationship.

8. The quantum sensor as described in claim 6, characterized in that, The lubrication system is a rolling bearing, a sliding bearing, or a gear pair.

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