TWI741845B - System and method for detecting lubricating oil quality - Google Patents

Abstract

The present invention provides a method for detecting lubricating oil quality, which is used to evaluate the quality and service life of the lubricating oil by detecting physical property indexes of lubricating oil. The method comprises the following steps: (a) detecting basic physical properties of the lubricating oil at various temperature to obtain a physical property index relationship formula between the basic physical properties and temperature, wherein the basic physical properties comprises at least viscosity and electrical conductivity; (b) coating the lubricating oil to be tested on surface of a rotation shaft of a lubricating oil quality inspection system, driving the rotating shaft in a first speed to raise temperature of the lubricating oil to be tested to a first temperature, and detecting electrical conductivity of the lubricating oil and the torque it bears in use; c) calculating viscosity μ _fof the lubricating oil to be tested in use state by the physical property index relationship formula based on the electrical conductivity detected in step.

Description

Lubricant quality detection system and detection method

The present invention relates to a detection system and detection method for oil products, in particular a lubricating oil quality detection system and detection method for detecting when simulating mechanical operation state

λ

10)，區分為邊界潤滑、流體油膜潤滑(彈液動潤滑、液動潤滑)與混合潤滑；在實務上，當溫度提高時，油膜黏度值也會隨之降低，導致油膜劣化及承壓能力下降。而在機械作動的過程中，金屬表面粗糙度與油膜品質之變異，仍存在理論無法完善解釋之存疑，油膜磨潤性於實務之探究，有其必要性。 Lubricating oil is used to protect the internal components of the machine and can form an oil film on the metal surface to reduce wear between metals. Generally speaking, the impact of high load, extreme temperature and humidity changes and acid-base environment on the quality of the oil film often leads to the deterioration of the molecular structure of the oil film and the failure of the oil film's wearability. Therefore, the change of oil film viscosity can be regarded as the main observation index in the lubrication system. Theoretically, the lubrication form of the oil film can be determined by the ratio λ(0

λ

10) It is divided into boundary lubrication, fluid oil film lubrication (elasto-hydraulic lubrication, hydraulic lubrication) and mixed lubrication; in practice, when the temperature increases, the viscosity of the oil film will also decrease, resulting in deterioration of the oil film and pressure-bearing capacity decline. In the process of mechanical operation, the variation of the metal surface roughness and the quality of the oil film still has doubts that the theory can not fully explain it. It is necessary to explore the wearability of the oil film in practice.

Regarding the effect of temperature on the viscosity coefficient, friction coefficient, test piece abrasion and oxide layer of 15W40 multi-grade engine oil, the research results show that under the same shear rate, the increase in temperature leads to the dynamic viscosity and viscosity of the base oil. The index dropped. In addition, when the oil film is under pressure, disturbed by movement conditions, thermally damaged, oxidized, and contaminated by additives or coolants, it will cause the oil film to crack and reduce the viscosity value. On the other hand, the electrical conductivity characteristics and applied theory of the oil film still lack systematic and practical exploration and verification, and there is a gap between theory and practice.

Therefore, although the relationship between oil film and conductivity has been discussed a little in scientific research, so far no practical application results have been seen. The reason is the lack of devices and equipment that can actually simulate temperature changes, speed changes, and discharge signals.

Therefore, the practicality emphasized in the present invention is to construct a controllable oil film ambient temperature and rotation speed, and use electrical signals to detect the oil film conductivity, and then predict the oil viscosity and lifespan detection system. Based on theoretical derivation, the system platform for oil film testing is independently developed, designed and manufactured, and through basic testing, mainstream testing, evolutionary testing and verification testing, the parameters that can control the deterioration of the oil film are displayed and the measurement indicators are measured. By measuring the conduction torque, viscosity and discharge signal in the oil film, and establishing a parameter model for prediction and application. Then use statistical methods to verify the randomness of the residuals and the stability of the system, and make decisions about the significant parameter factors that cause the deterioration of the oil film quality. The realization of this technology is both scientific and practical, and can be extended to monitor the wearability of fluid machinery to achieve immediate improvement in the quality of the oil film, and to improve the lubrication effect and energy-saving benefits.

In other words, the present invention can provide a lubricating oil quality detection system, which includes: a rotating unit, which includes a motor, a torque sensor, a sleeve, and a rotating shaft arranged in the sleeve, the outer surface of which is coated with The oil to be tested, and there is a specific distance between the casing and the rotating shaft, the motor is connected to one end of the rotating shaft, and is used to drive the rotating shaft to rotate at a specific speed. The torque sensor is used to detect The torque that the oil to be tested is subjected to during the rotation; the heat treatment unit includes a heater and a temperature sensor, the heater is used to heat the rotating shaft, and the temperature sensor is used to detect the to-be Measure the temperature of the oil product; an electrical processing unit, which includes an electrode module and an oscilloscope, the electrode module is electrically connected to the rotating shaft, for applying a voltage to the rotating shaft and detecting the conductivity of the oil product to be tested The oscilloscope is electrically connected to the electrode module to display the conductivity and discharge waveform of the oil to be tested; and the power supply The supply unit is electrically connected with the rotating unit, the heat treatment unit, and the electric processing unit to provide power required for operation.

式中，h為油膜厚度、μ為待測油品黏度、P為油膜壓力、U為切線速度。 According to an embodiment of the present invention, the specific distance is at least greater than the thickness of the oil film formed by the oil product to be tested on the outer surface of the rotating shaft, and the oil film thickness is calculated by the following mathematical formula D:

In the formula, h is the oil film thickness, μ is the viscosity of the oil to be tested, P is the oil film pressure, and U is the tangent velocity.

Furthermore, the present invention can also provide a lubricating oil quality detection method, which is used to detect the physical properties of the lubricating oil to evaluate the quality and service life of the lubricating oil, including the following steps: (a) detecting the lubricating oil to be tested The basic physical properties at different temperatures to obtain the physical property index relationship between the basic physical properties and temperature, where the basic physical properties include at least viscosity and conductivity; (b) coating the tested lubricant on the aforementioned lubricant quality The surface of the rotating shaft in the detection system, while driving the rotating shaft to rotate at the first speed, while raising the temperature of the lubricating oil to be tested to the first temperature, the electrical conductivity of the lubricating oil in use and the Torque; (c) Based on the electrical conductivity detected in the above step (b), the viscosity μ _{f of} the lubricating oil to be tested in the use state is calculated by the physical property index relationship formula.

式中，V為電壓、I為電流、N為轉動軸轉速、l為轉動軸長度、r為轉動軸半徑、ω為角速度、c為轉動軸與套管之間的寬度。 According to an embodiment of the present invention, in the step (c), the viscosity μ _f and the torque Tω of the lubricating oil under use in the use state conform to the following mathematical formula (H):

In the formula, V is the voltage, I is the current, N is the rotation speed of the rotating shaft, l is the length of the rotating shaft, r is the radius of the rotating shaft, ω is the angular velocity, and c is the width between the rotating shaft and the sleeve.

式中，μ表示黏度、t表示第一溫度、G表示導電度。 According to an embodiment of the present invention, when the lubricating oil is a K85 multi-grade engine oil, the physical property index relational expression in the step (a) is as shown in the following mathematical formula (I):

In the formula, μ represents viscosity, t represents the first temperature, and G represents electrical conductivity.

式中，μ表示黏度、t表示第一溫度、G表示導電度。 According to an embodiment of the present invention, when the lubricating oil is CXL refrigerated extreme pressure oil, the physical property index relational expression in the step (a) is as shown in the following mathematical formula (II):

In the formula, μ represents viscosity, t represents the first temperature, and G represents electrical conductivity.

式中，μ表示黏度、t表示第一溫度、G表示導電度。 According to an embodiment of the present invention, when the lubricating oil is PM mineral oil, the physical property index relational expression in the step (a) is as follows:

In the formula, μ represents viscosity, t represents the first temperature, and G represents electrical conductivity.

式中，μ為未經使用之該潤滑油黏度、P為油膜壓力、U為切線速度。 According to an embodiment of the present invention, in the step (b), the thickness h of the lubricating oil coated on the surface of the rotating shaft conforms to the following mathematical formula D:

In the formula, μ is the unused viscosity of the lubricating oil, P is the oil film pressure, and U is the tangential velocity.

According to an embodiment of the present invention, in the step (b), the first temperature is in the range of 40° C. to 90° C.; the first rotation speed is in the range of 120 rpm to 210 rpm.

According to an embodiment of the present invention, the service life of the lubricating oil is defined as the time it takes for the measured conductivity of the lubricating oil to rise from a stable value during the rotation of the lubricating oil. .

1: Rotating unit

2: Heat treatment unit

21: heater

22: Temperature sensor

3: Electric processing unit

31: Electrode module

32: Oscilloscope

4: Power supply unit

9: Conductivity measurement device

91: Electrode group

92: heating plate

93: Laser displacement sensor

94: Oscilloscope

95: Rail

S1~S3: steps

Fig. 1 is a schematic diagram showing the configuration of the lubricating oil quality detection system of the present invention.

2A is a diagram showing the flow field change and pressure state of the lubricating oil to be tested in the lubricating oil quality detection system of the present invention.

2B is a free-body diagram showing the micro fluid element of the lubricating oil to be tested in the lubricating oil quality detection system of the present invention subjected to force in the x direction.

Fig. 3 is a flow chart showing the method of lubricating oil quality inspection using the lubricating oil quality inspection system of the present invention.

Fig. 4 is a diagram showing the structure of a conductivity measuring device used in an embodiment of the present invention.

5A is a schematic diagram showing the relationship between conductivity and viscosity of K85 multi-grade oil, CXL refrigerated extreme pressure oil, and PM mineral oil in an embodiment of the present invention and temperature.

5B is a schematic diagram showing the relationship between conductivity and viscosity of K85 multi-grade engine oil, CXL refrigerated extreme pressure oil, and PM mineral oil in an embodiment of the present invention.

Fig. 6 is a schematic diagram showing the relationship between torque, temperature and rotation speed in an embodiment of the present invention.

FIG. 7 is a schematic diagram showing the relationship between conductivity, temperature and rotation speed in an embodiment of the present invention.

FIG. 8A shows the experimental results (yij) of the torque measured in Examples 1 to 20 of the present invention, and the distribution of the torque experimental values of the full factor verification test under the 95% confidence interval.

Figure 8B is a semi-domain diagram showing the random allocation of residuals based on Figure 8A

FIG. 9A shows the experimental result (yij) of the conductivity measured by the embodiment of the present invention, and the distribution of the experimental value of the conductivity of the full factor verification test under the 95% confidence interval.

Figure 9B is a semi-domain diagram showing the random allocation of residuals based on Figure 9A

In order to make the purpose, technical features, and advantages of the present invention better known to those in the relevant technical field and able to implement the present invention, the technical features and implementation modes of the present invention are illustrated in detail in conjunction with the accompanying drawings and listed here. The preferred embodiment progress description. The drawings to be compared in the following text are schematic representations related to the features of the present invention, and are not and do not need to be drawn completely based on actual situations.

The singular forms "一", "one" and "the" used in this article also include plural forms, unless the context clearly indicates otherwise. Furthermore, it should be understood that when used in this specification, the terms "including" and/or "including" designate the presence of the described features, elements and/or units, but do not exclude the presence or addition of one or more other features, elements and/ Or unit, together first stated. Moreover, in the following detailed description of each embodiment with reference to the drawings, it will be clearly presented that the directional terms mentioned in the following embodiments, for example: "up", "down", "left", "right", "Front", "Back", etc., are just for reference to the directions of the attached icons. Therefore, the directional terms used are used to illustrate, but not to limit the present invention.

Furthermore, those who are familiar with this technology should also understand that the listed embodiments and accompanying drawings are only for reference and explanation, and are not intended to limit the present invention; they can be easily implemented based on these records. Inventions completed by modification or alteration are also deemed to be within the scope not departing from the spirit and intent of the present invention. Of course, these inventions are also included in the scope of the patent application of the present invention.

First, please refer to FIG. 1, which is a schematic diagram showing the configuration of the lubricating oil quality inspection system of the present invention. The lubricating oil quality inspection system includes a rotating unit 1, a heat treatment unit 2, an electric processing unit 3, and a power supply unit 4.

The rotating unit 1 includes a motor, a torque sensor, a sleeve, and a rotating shaft arranged in the sleeve. A specific distance is provided between the sleeve and the rotating shaft. The motor is connected to one end of the rotating shaft. The sensor is arranged in the casing. During quality inspection, the lubricating oil to be tested is coated on the outer surface of the rotating shaft to form an oil film, and the motor is used to drive the rotating shaft to rotate at a specific speed, and then the torque sensor is used to detect the oil film during rotation. The torque.

The heat treatment unit 2 includes a heater 21 and a temperature sensor 22. The heater 21 is connected to the rotating shaft to heat the rotating shaft to heat up the lubricating oil to be measured. The temperature sensor 22 is used to detect The temperature of the lubricating oil to be tested during the heating process.

According to the technical idea of the present invention, a heating element is provided in the heater 21, and the heating element can be from a titanium metal tube, a titanium metal rod, a resistance heater, an arc heater, an infrared heater, a heating rod, and a heating probe. Choose at least one of them.

The electrical processing unit 3 includes an electrode module 31 and an oscilloscope 32. The electrode module 31 is electrically connected to the rotating shaft and can apply a voltage to the rotating shaft and detect the conductivity and discharge waveform of the lubricating oil to be tested. The oscilloscope 32 is electrically connected to the electrode module 31 to display the conductivity and discharge waveform of the lubricating oil to be tested.

The power supply unit 4 is electrically connected to the rotating unit 1, the heat treatment unit 2, and the electric processing unit 3 to provide power required for operation.

According to the technical idea of the present invention, the specific distance between the sleeve and the rotating shaft depends on the viscosity of the rotating shaft and the lubricating oil to be tested. Please refer to FIGS. 2A and 2B. FIG. 2A shows the flow field change and pressure state of the lubricating oil to be tested in the lubricating oil quality detection system of the present invention, and FIG. 2B shows the lubricating oil to be tested in the lubricating oil of the present invention. The free-body diagram of the micro fluid element in the quality inspection system under force in the x direction.

According to Newton’s second law of motion, we can derive the motion equation of fluid mechanics (Navier-Stokes equation), and then through the motion behavior of fluid dynamics between lubricating bearings as shown in Figure 2B, the following mathematics can be derived Formula A:

Where: P is the oil film pressure, τ is the fluid shear stress

From Figure 2B, the boundary condition of no slip can be considered, that is, when the boundary condition is y=0, u=0, and when y=h, the pressure drop between u=U and the x-axis can be determined by the fluid viscosity and velocity. The gradient is brought into the mathematical formula A and integrated, so that the function of the velocity u distribution can be obtained, as shown in the following mathematical formula B:

Considering the z-axis as the unit distance, and integrating the function of Mathematical Formula 2 on the y-axis from 0 to the gap h, the mass flow rate Q _f flowing through the yz section can be obtained, as shown in the following Mathematical Formula C:

When considering that the fluid is an incompressible flow, that is, the flow rate of the net value passing through the cross-sectional area x direction is zero, rearranging the formula C to obtain the Ocvirk's short bearing approximation, as shown in the following mathematical formula D Shown:

The oil film thickness h formed by the lubricating oil to be tested on the surface of the rotating shaft can be calculated from the mathematical formula D, and the distance between the rotating shaft and the sleeve must be greater than the oil film thickness h, so that the oil film can be on the rotating shaft and The flow between the casings, the controlled speed and induced shear force can accelerate the cracking of the oil film. In the embodiment of the present invention, when the rotation speed is 8000 rpm and the viscosity value is 90 cP, the maximum oil film thickness can be calculated to be about 0.6 mm; therefore, the distance between the rotating shaft 14 and the sleeve 13 must be greater than 0.6 mm. In the embodiment of the present invention, the distance between the rotating shaft 14 and the sleeve 13 is designed to be 1mm, so that the radial distance between the oil film and the sleeve 13 is 0.4mm, so as to test the shear effect generated between the streamlines. And collect the discharge signal in this interval.

The lubricating oil quality detection system of the present invention can detect the temperature of the lubricating oil film, its conductivity, and the torque it bears in real time, and detect the quality of the lubricating oil film through the discharge behavior through the change of the conductivity, and establish the relationship between the viscosity value of the oil film and the conductivity. . Its theoretical basis is based on the principle of conservation of energy, which separates the friction loss of the moving parts, and then measures the load and shear effects between the oil films, as shown in the following mathematical formula E: IV = Tω - T _lods ω .......Mathematics Formula E

Where: I is the current, V is the voltage, T is the torque, ω is the angular velocity, and T _loss is the torque caused by friction.

After the friction loss of the separated moving parts, the remaining friction loss is the viscosity of the oil film. Therefore, the fluid shear stress τ can be rewritten as the following mathematical formula F:

Then use the following mathematical formula G to calculate the torque loss caused by the viscous force:

Where: N is the rotational speed of the rotating shaft, l is the length of the rotating shaft, r is the radius of the rotating shaft, and c is the distance between the rotating shaft and the sleeve.

Then rewrite the mathematical formula E into the theoretical viscosity coefficient model, as shown in the following mathematical formula H:

From this, the relationship between the viscosity μ and the torque Tω can be derived. In addition, the basic physical properties such as viscosity and electrical conductivity of the lubricating oil to be tested before the test are tested to obtain the physical property index relationship between the basic physical properties and the temperature, and then the relationship between the viscosity and the electrical conductivity can be obtained.

Next, please refer to Figure 3, which is a flow chart showing the method of lubricating oil quality inspection using the lubricating oil quality inspection system of the present invention, which includes the following steps: S1: detecting the basic physical properties of the lubricating oil to be tested at different temperatures, In order to obtain the physical property index relationship between the basic physical property and the temperature, the basic physical property at least includes viscosity and electrical conductivity; (S2: After coating the lubricating oil to be tested on the surface of the rotating shaft in the lubricating oil quality inspection system, while driving the rotating shaft to rotate at the first speed, the temperature of the lubricating oil to be tested is raised to the first temperature. Detect the conductivity of the lubricating oil in use and the torque it bears; S3: Based on the conductivity detected in step (b) above, use the physical property index relational formula to calculate the lubricating oil to be tested in use The viscosity μf.

In addition, because the lubricating oil before use is generally non-conductive, the conductivity is extremely low or close to zero. When the lubricating oil is used in mechanical equipment, as the machine rotates and wears, the lubricating oil is The formed oil film breaks through the insulation and produces ionization channels, causing the voltage to drop and the current will be discharged from the direct output of the capacitor. At this time, the conductivity of the oil film will start to rise from a certain value; therefore, through the lubricating oil quality detection system of the present invention, The time it takes for the measured conductivity of the lubricating oil to rise from a stable value during the rotation of the lubricating oil can be defined as the service life of the lubricating oil.

In order to describe the present invention more fully and completely, the following is an illustrative description of the embodiments and specific examples of the present invention; however, these do not represent the intention of the only form that can be practiced or used in the specific examples of the present invention. . The embodiments cover the characteristics and structures of a number of specific examples; and the process steps and sequence of operating these specific examples. However, in other examples, it can also be accomplished by the same or equivalent functions and sequence of steps.

"Establishing the relationship formula of oil physical properties"

First, measure the viscosity and conductivity of different types of oils in different temperature environments. The conductivity measurement device 9 used is shown in FIG. 4 and includes an electrode group 91, a heating plate 92, a laser displacement sensor 93, an oscilloscope 94, and a guide rail 95. The guide rail 95 is used to fix the position of the electrode group 91 to avoid the displacement of the electrode group 91; the oil to be tested is coated on the two electrode plates of the electrode group 91 In between, the laser displacement sensor 93 is electrically connected to the electrode group 91 to sense the thickness h'of the oil product to be tested; the heating plate 92 is arranged under the electrode group 91 to heat the oil product to be tested ; Oscilloscope 94 is used to apply voltage to the electrode group 91, and to detect the voltage drop, peak current value and discharge waveform generated by the discharge effect in the oil to be tested, and to monitor the conductivity in real time. In addition, the viscosity is measured by measuring the viscosity of the oil to be tested heated to different temperatures.

In this embodiment, unused K85 multi-grade oil, CXL refrigerated extreme pressure oil, and PM mineral oil are used to measure the conductivity and viscosity of each oil when it is heated to 40, 50, 70, 80, and 90°C. value. The operating conditions of the conductivity measurement device are: load: 550 ± 5.5 g, open voltage: 0.3 V, heating time: 180 seconds, and sampling frequency: 125 kHz. Then, plot the measured conductivity and viscosity data into Figure 5A, where the black line represents the relationship between viscosity and temperature, and the red line represents the relationship between conductivity and temperature.

From the results of Table 1 and Figure 5A above, it can be seen that as the temperature increases, the viscosity decreases due to the destruction of the molecular chain, which may generate ionic clusters of free radicals, which increases the conductivity of the oil film. Among them, it is found that when PM mineral oil is at 70°C, it is possible that the molecular chain of the oil has been largely destroyed, causing the conductivity to rise sharply and forming a good electrical conductor.

Then, based on the data in Table 1 above, the relationship between the viscosity of K85 multi-grade oil, CXL refrigerated extreme pressure oil, and PM mineral oil and conductivity is derived as shown in Figure 5B, and the relationship is as follows: Viscosity of K85 multi-grade oil Meets the following mathematical formula I with conductivity:

The viscosity and conductivity of CXL refrigerated extreme pressure oil meet the following mathematical formula II:

The viscosity and conductivity of PM mineral oil meet the following mathematical formula III:

In the above equations I to III, μ represents the viscosity of the oil, t represents the temperature of the oil, and G represents the conductivity of the oil.

In addition, after the residual analysis test, the accuracy of the above equations I to III are as high as 94.94%, 82.17%, and 96.28%, respectively.

"Examples"

In this embodiment, K85 multi-grade engine oil is applied to the surface of the rotating shaft in the lubricating oil quality inspection system of the present invention and the rotating shaft is driven to rotate at 120 rpm, 150 rpm, 180 rpm, and 210 rpm, and heated to 40° C., 50 rpm. ℃, 60℃, 70℃, 80℃ rotate at the speed shown in Table 2 while heating the lubricating oil to the temperature shown in Table 2. Measure the conductivity of the lubricating oil and the torque it bears during the rotation process, and draw them as Figure 6 and Figure 7, respectively.

Figure 6 is a schematic diagram of torque changes at different temperatures and speeds. It can be seen from the results in Fig. 6 that when the rotation speed is 180 rpm and the oil film temperature is increased from 40°C to 80°C, the torque measurement value is greatly reduced by about 91%, indicating that the viscosity of the oil film will decrease as the temperature increases. In addition, Figure 7 is a schematic diagram of the electrical conductivity changes at different temperatures and rotational speeds. Similarly, as shown in Figure 7, when the rotational speed is 180 rpm and the oil film temperature increases from 40°C to 70°C, the electrical conductivity will change from 0.82×10 ^-4 S/ s rises to 49.61×10 ^-4 S/s, but when the temperature continues to increase, the conductivity turns to a downward trend, and reaches the lowest measured value of 2.51×10 ^-4 S/s at the oil film temperature of 80°C.

"Statistical Analysis"

1. The influence of temperature on the basic physical properties of the oil film

The data obtained in the foregoing examples were subjected to analysis of variance (ANOVA), and the results obtained are shown in Table 3.

After statistics and verification (α=5%), temperature has a very significant influence on viscosity, and the verification value in F distribution is as high as 238.26 (F _cal =238.26>>F _5,10 =3.33), and the degree of temperature factor contribution (PCR) is 94.59%. Although different oil types can change this difference, its influence (F _cal =26.44) is not as good as temperature. Furthermore, the extreme pressure additives often added to engine oils contain metallic elements, which promote the conductivity to be higher than that of general mineral oils. Make the added components of the oil the main factor controlling the conductivity, the F value reaches 18.08 (F _cal =18.08>F _2,10 =4.10), and the contribution of the oil factor is 51.57%.

2. The influence of the shear effect of fluid velocity on the viscosity of the oil film

)及信賴區間(confidence interval,CI)之範圍，對所建構之品質監測系統進行穩定度之評估。 The torque obtained in the foregoing embodiment is derived from the fitting value of the statistical model adequacy method (model adequacy) (

) And the range of confidence interval (CI) to evaluate the stability of the constructed quality monitoring system.

As shown in Figure 8A, under the 95% confidence interval, in the full factor verification test in the embodiment, the results all show that after the oil film is degraded by the shear force generated by the torque, there is only one parameter combination (70°C, 120rpm) It is an outlier in the model that is far away from the model fitting curve and falls outside the curve of the confidence interval.

Figure 8B shows the half-normal plots of the random allocation of residuals (Daniel half-normal plots). In the verification test, the tolerable torque after observing the deterioration of the oil film, the error of the measurement and the parameters are all randomly distributed and not concentrated in any test. When the two residual points (70°C, 120rpm) and (70°C, 180rpm) of the parameter combination are excluded, the fitting accuracy rises from 83.86% to 94.78%, which means that the oil film quality real-time monitoring system is a robust design.

3. The influence of the shear effect of fluid velocity on the conductivity of the oil film

)及信賴區間(confidence interval,CI)之範圍，對所建構之磨潤監測系統進行穩定度之評估。 The fitting values (

) And the range of confidence interval (CI) to evaluate the stability of the constructed wear monitoring system.

FIG. 9A shows the experimental results (y _ij ) of the conductivity measured in the embodiment. The distribution of the experimental values of the conductivity in the full factor verification test in the embodiment is within the 95% confidence interval. The results show that in the conductivity experiment results, only one parameter combination (70℃, 210rpm) is far from the model fitting curve and falls outside the curve of the confidence interval, which is an outlier in the model. And determine the randomness of the residual distribution in Figure 11(b), when the six outliers of the parameter combination (70℃,210rpm), (70℃,120rpm), (60℃,120rpm), (60℃) are excluded ,210rpm), (70℃,150rpm) and (65℃,120rpm), the fitting accuracy increased from 52.92% to 90.13%. In the suitability analysis of the conductivity model, all measured values are within the confidence interval, that is, the constructed discharge real-time monitoring oil film quality system is extremely stable, and the conductivity measurement system is also a robust system.

In addition, the conductivity and torque obtained in the foregoing examples were subjected to variance analysis (ANOVA), and the results obtained are shown in Table 4.

From the results in Table 4 above, it can be seen that temperature has a significant effect on the torque that the oil film can withstand. The F value reaches 23.34 (F _cal =23.34>F _8,24 =2.36), and the contribution of temperature to the torque observation index is 83.04% . This phenomenon is consistent with the results of the basic physical properties of the oil film. The viscosity of the oil drops sharply with the increase in temperature, which reduces the friction between the oil films and reduces the ability to withstand torque. On the other hand, the observation of temperature on conductivity presents a random influence, but it is not significant. It is speculated that the cause is the interference of the polar additives on the conductivity, and further conversion between the time domain and the frequency domain is required to identify the source of the interference.

It can be seen from the above embodiments that the lubricating oil quality detection system and detection method of the present invention have the following advantages:

1. Establish the relationship between the electrical signal and the quality of the oil film: the extraction of the torque signal is combined with the calculation of the fluid mechanics formula, and the relationship between the viscosity and the conductivity is established to observe the influence of the conductivity on the wear state of the machine during the rotation. .

2. Real environment simulation: The system can control the variable environment temperature and rotation speed, and capture the signals of the oil's shear resistance and electrical conductivity to derive the parameter model.

3. Real-time quality monitoring: Set the threshold of conductivity by changing the linear velocity and oil film temperature as a failure benchmark, observe the time required for the electrical circuit to generate ionization channels between the oil films, judge the wearability of different oil films, and combine with statistical models Establish optimized parameters and predict oil film failure time.

In summary, the content of the present invention has been exemplified by the above embodiments, but the present invention is not limited to these embodiments. Those with ordinary knowledge in the technical field to which the present invention belongs can make various changes and modifications without departing from the spirit and scope of the present invention; for example, combining or changing the various technical contents illustrated in the foregoing embodiments As new implementations, these implementations are of course regarded as one of the contents of the present invention. Therefore, the scope of protection in this case also includes the scope of patent application and its defined scope described later.

1: Rotating unit

2: Heat treatment unit

21: heater

22: Temperature sensor

3: Electric processing unit

31: Electrode module

32: Oscilloscope

4: Power supply unit

Claims (10)

A lubricating oil quality detection system, which includes: a rotating unit, which includes a motor, a torque sensor, a sleeve, and a rotating shaft arranged in the sleeve, the outer surface of the rotating shaft is coated with the oil to be tested, and A specific distance is provided between the sleeve and the rotating shaft, the motor is connected to one end of the rotating shaft to drive the rotating shaft to rotate at a specific speed, and the torque sensor is used to detect whether the oil to be tested is in The torque received during the rotation; the heat treatment unit, which includes a heater and a temperature sensor, the heater is used to heat the rotating shaft, and the temperature sensor is used to detect the temperature of the oil to be tested; The electrical processing unit includes an electrode module and an oscilloscope. The electrode module is electrically connected to the rotating shaft for applying a voltage to the rotating shaft and detecting the conductivity and discharge waveform of the oil to be tested. An oscilloscope is electrically connected to the electrode module to display the conductivity and discharge waveform of the oil to be tested; and a power supply unit, which is electrically connected to the rotating unit, the heat treatment unit, and the electric processing unit, Used to provide power required for operation. For example, the lubricating oil quality inspection system of claim 1, wherein the specific distance is at least greater than the thickness of the oil film formed by the oil product to be tested on the outer surface of the rotating shaft, and the oil film thickness is calculated by the following mathematical formula D:

In the formula, h is the oil film thickness, μ is the viscosity of the oil to be tested, P is the oil film pressure, and U is the tangent velocity. A lubricating oil quality detection method, which is used to detect the physical properties of lubricating oil to evaluate the quality and service life of the lubricating oil, including the following steps: (a) detecting the basic physical properties of the lubricating oil to be tested at different temperatures, To obtain the physical property index relationship between the basic physical properties and temperature, where the basic physical properties include at least viscosity and conductivity; (b) apply the lubricating oil to be tested in the lubricating oil quality inspection system of claim 1 or 2 The surface of the rotating shaft, while driving the rotating shaft to rotate at the first speed, while heating the lubricating oil to be tested to the first temperature, the conductivity of the lubricating oil in use and the torque it bears are detected (C) Based on the electrical conductivity detected in the above step (b), the viscosity μ _{f of} the lubricating oil to be tested in the use state is calculated by the physical property index relationship formula. Such as the lubricating oil quality detection method of claim 3, wherein the viscosity μ _f and torque Tω of the lubricating oil to be tested in the use state in the step (c) meet the following mathematical formula (H):

In the formula, V is the voltage, I is the current, N is the rotation speed of the rotating shaft, l is the length of the rotating shaft, r is the radius of the rotating shaft, ω is the angular velocity, and c is the width between the rotating shaft and the sleeve. Such as the lubricating oil quality inspection method of claim 3, wherein when the lubricating oil is K85 multi-grade engine oil, the physical property index relational expression in this step (a) is as shown in the following mathematical formula (I):

In the formula, μ represents viscosity, t represents the first temperature, and G represents electrical conductivity. Such as the lubricating oil quality inspection method of claim 3, wherein when the lubricating oil is CXL refrigerated extreme pressure oil, the physical property index relational expression in this step (a) is as shown in the following mathematical formula (II):

In the formula, μ represents viscosity, t represents the first temperature, and G represents electrical conductivity. Such as the lubricating oil quality detection method of claim 3, wherein when the lubricating oil is PM mineral oil, the physical property index relational expression in this step (a) is as follows:

In the formula, μ represents viscosity, t represents the first temperature, and G represents electrical conductivity. Such as claim 3 of the lubricating oil quality detection method, wherein in the step (b), the thickness h of the lubricating oil coated on the surface of the rotating shaft meets the following mathematical formula 4:

In the formula, μ is the unused viscosity of the lubricating oil, P is the oil film pressure, and U is the tangential speed. Such as the lubricating oil quality detection method of claim 3, wherein in the step (b), the first temperature is in the range of 40°C to 90°C; the first rotation speed is in the range of 120rpm to 210rpm. Such as the lubricating oil quality detection method of claim 3, wherein the service life of the lubricating oil is defined as the time it takes for the measured conductivity of the lubricating oil to rise from a stable value during the rotation of the lubricating oil.

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