A method and system for detecting the wear resistance of a diesel anti-wear agent

Abstract

The application relates to the technical field of material performance testing, in particular to a diesel anti-wear agent wear resistance detection method and system; the method comprises the following steps: acquiring a real-time friction coefficient time sequence of a friction pair in a friction and wear test process; reconstructing a phase space of the friction coefficient time sequence to obtain a state vector representing dynamic evolution of a friction system; for any moment, calculating a phase space dispersion degree in an analysis time window constructed with the moment as a benchmark, the phase space dispersion degree representing a dispersion range of a space trajectory; calculating a mutation intensity of the friction coefficient time sequence, nonlinearly coupling the phase space dispersion degree and the mutation intensity to obtain a wear abnormality degree used for representing protection performance of the anti-wear agent; taking a time point at which the wear abnormality degree exceeds a preset threshold for the first time as an index for evaluating wear resistance of the anti-wear agent. The application has the effect of improving comprehensiveness of anti-wear agent evaluation.

Description

Technical Field

[0001] This application relates to the field of material performance testing technology, and in particular to a method and system for testing the wear resistance of diesel anti-wear agents. Background Technology

[0002] Diesel fuel systems are highly susceptible to boundary friction and wear under high pressure, high speed, and high temperature operating conditions. To reduce mechanical loss and extend system life, anti-wear agents are typically added to diesel fuel to enhance lubrication performance. Currently, the High Frequency Reciprocating Rig (HFRR) test has become an internationally recognized standard for evaluating diesel fuel lubrication performance (ASTM D6079, ISO 12156-1). This test simulates the reciprocating motion of internal components of the fuel injection system through friction pairs. After a specific period of reciprocating motion, the diameter of the wear scar on the steel ball is measured to reflect the anti-wear capability of the lubricating oil film.

[0003] Existing HFRR tests have significant limitations. Their evaluation relies on a single endpoint wear scar diameter (WSD), essentially a post-hoc analysis that only reflects the cumulative wear after the test, failing to reveal the dynamic changes in the wear process. In fact, the actual performance of anti-wear agents is more reflected in the dynamic processes of protective film formation, maintenance, and failure. Especially when the lubricating film begins to degrade and the friction state transitions from a stable phase to a severe wear phase, microscopic changes often precede macroscopic wear results. Traditional methods cannot capture these early microscopic anomalies caused by protective film rupture, thus resulting in an incomplete evaluation of anti-wear agent performance and hindering the development of more efficient and reliable anti-wear agent formulations. Summary of the Invention

[0004] In order to more comprehensively evaluate the performance of anti-wear agents and thus facilitate the development of more efficient anti-wear agents, this application provides a method and system for testing the wear resistance of diesel anti-wear agents.

[0005] In a first aspect, this application provides a method for testing the wear resistance of a diesel anti-wear agent, employing the following technical solution:

[0006] A method for testing the wear resistance of a diesel anti-wear agent includes: acquiring a real-time friction coefficient time series of a friction pair during a friction and wear test; reconstructing the phase space of the friction coefficient time series to obtain a state vector characterizing the dynamic evolution of the friction system, wherein the state vector at each moment constitutes a spatial trajectory characterizing the dynamic evolution of the friction system; for any given moment, calculating the phase space dispersion within an analysis time window constructed based on that moment, wherein the phase space dispersion characterizes the dispersion range of the spatial trajectory; calculating the abrupt change intensity of the friction coefficient time series, wherein the abrupt change intensity is the product of the degree of deviation of the friction coefficient from its baseline and the instantaneous growth rate; nonlinearly coupling the phase space dispersion and the abrupt change intensity to obtain a wear anomaly degree used to characterize the protective performance of the anti-wear agent; and using the time point at which the wear anomaly degree first exceeds a preset threshold as an indicator for evaluating the wear resistance of the anti-wear agent.

[0007] By acquiring the real-time friction coefficient time series of the friction pair during the friction and wear test, the lubrication effect of the anti-wear agent at different stages can be continuously recorded. Phase space reconstruction maps the one-dimensional time series to a high-dimensional state space, and the generated spatial trajectory reflects the stability differences of the friction system at different wear stages. Phase space dispersion reflects the degree of dispersion of the spatial trajectory; when the friction system transitions from stable wear to severe wear, the phase space dispersion increases, thus providing an early criterion for wear anomalies. Simultaneously, the abrupt change intensity of the friction coefficient time series is calculated, enabling the capture of instantaneous energy surge events. Finally, the phase space dispersion and abrupt change intensity are nonlinearly coupled, comprehensively considering the macroscopic stability and microscopic abrupt change trend of the system. The resulting wear anomaly degree becomes a comprehensive index characterizing the protective performance of the anti-wear agent. By determining the time point at which the wear anomaly first exceeds the threshold, early signs of a wear state transitioning from stable to drastic can be identified. This allows for a deeper evaluation of anti-wear agents, not only from the perspective of wear scar size, but also from the perspective of the first failure time. This enables a more in-depth and accurate quantitative assessment of anti-wear agent performance, providing a data foundation for the subsequent research and optimization of anti-wear agents.

[0008] Optionally, the step of calculating the phase space dispersion within the analysis time window constructed based on that moment includes: calculating the covariance matrix of the point set composed of all state vectors within the analysis time window, and using the logarithm of the determinant of the covariance matrix as the phase space dispersion.

[0009] The covariance matrix can characterize the correlation and dispersion of the state vector in each dimension. Its determinant reflects the size of the volume occupied by the state point in the phase space. By taking the logarithm of the determinant, we can not only avoid the scale shift caused by the large difference in numerical magnitude under different experimental conditions, but also make the trend of the dispersion of the phase space more linear.

[0010] Optionally, a moving average filter can be applied to the friction coefficient time series to obtain the baseline of the friction coefficient.

[0011] The moving average baseline can dynamically adapt to the slow drift caused by factors such as temperature during the test, so that the calculation of the abrupt change intensity can more accurately identify the real abnormal peaks caused by the deterioration of the wear condition.

[0012] Optionally, the window length for the moving average filter is 50 to 70 seconds.

[0013] A window length of 50 to 70 seconds strikes a balance between smoothing out short-term noise and responding to long-term trends, ensuring baseline stability without being too sluggish in responding to real changes in wear conditions.

[0014] Optionally, the step of nonlinearly coupling the phase space dispersion with the abrupt change intensity to obtain the wear anomaly degree used to characterize the protective performance of the anti-wear agent includes: analyzing the overall level of the phase space dispersion at each time point to obtain the reference dispersion; for any time point, taking the ratio of the phase space dispersion to its reference dispersion as the spatial deviation degree; taking the sum of the product of the average value of the abrupt change intensity in the analysis time window and the preset coupling coefficient and 1 as the adjustment coefficient; and taking the product of the adjustment coefficient and the spatial deviation degree as the wear anomaly degree.

[0015] The average values ​​of phase space dispersion and mutation intensity are nonlinearly combined using a preset coupling coefficient, so that the wear anomaly can reflect the system stability at the macro level and the instantaneous mutation behavior at the micro level.

[0016] Optionally, the average value of the spatial dispersion of each time phase within the preset stable wear stage of the friction and wear test can be used as the reference dispersion.

[0017] The statistical characteristics of the wear system during the initial stable period best represent the normal working state of the anti-wear agent. Therefore, the average value during the stable wear stage is taken as a reference.

[0018] Optionally, the phase space of the friction coefficient time series can be reconstructed using the delayed coordinate embedding method.

[0019] This method, based on Takens' theorem, can recover the dynamic phase space structure of a system from the time series itself when the system equations are unknown.

[0020] Optionally, the steps for obtaining the real-time friction coefficient time series of the friction pair during the friction and wear test include: real-time acquisition of the friction force signal between the friction pair, dividing the friction force in the friction force signal by a constant normal load to obtain the instantaneous friction coefficient value at the corresponding moment, arranging the friction coefficient values ​​in chronological order to form the original sequence, and preprocessing the original sequence to obtain the friction coefficient time series.

[0021] Optionally, the preprocessing steps for the original sequence include: bandpass filtering the original sequence.

[0022] Secondly, this application provides a system for testing the wear resistance of diesel anti-wear agents, employing the following technical solution:

[0023] A system for testing the wear resistance of a diesel anti-wear agent includes a processor and a memory. The memory stores computer program instructions, which, when executed by the processor, implement the aforementioned method for testing the wear resistance of a diesel anti-wear agent.

[0024] A computer program is generated from the above-mentioned method for testing the wear resistance of a diesel anti-wear agent and stored in a memory so that it can be loaded and executed by a processor. Thus, a system is created based on the memory and the processor for convenient use.

[0025] This application has the following technical effects:

[0026] By employing phase space reconstruction technology, a wear anomaly index capable of predicting lubricating oil film failure was constructed by integrating two indicators: phase space dispersion, which characterizes the macroscopic stability of the system, and abrupt change intensity, which captures microscopic instantaneous failures. This enables the evaluation of anti-wear agents not only to be conducted post-hoc but also to be monitored during the wear process, providing a new dynamic evaluation dimension for the development of more efficient anti-wear agents. Attached Figure Description

[0027] Figure 1 This is a flowchart of a method for testing the wear resistance of a diesel anti-wear agent according to an embodiment of this application. Detailed Implementation

[0028] This application discloses a method for testing the wear resistance of diesel anti-wear agents. It treats the friction and wear process as a dynamic system, reconstructing the one-dimensional real-time friction coefficient time series in phase space to map its evolution into a motion trajectory in a high-dimensional space. Based on this, it constructs phase space dispersion to evaluate the macroscopic stability of the trajectory and abrupt change intensity to capture instantaneous failure events at the microscopic level. Finally, through nonlinear coupling of these two dimensional indicators, it constructs a wear anomaly degree. Based on this index, it is possible to identify early signs of a wear state transitioning from stable to drastic, thus evaluating the actual performance of anti-wear agents from a perspective different from related technologies and providing a more data foundation for the research and development of anti-wear agents.

[0029] Reference Figure 1 This includes steps S1-S5.

[0030] S1: Obtain the real-time friction coefficient time series of the friction pair during the friction and wear test.

[0031] In conducting high-frequency reciprocating friction and wear tests ( During the process, real-time friction force signals are collected. The experimental setup follows relevant industry standards, such as... Standard. Test parameters were set to standard values, including reciprocating frequency, stroke, normal load, and test temperature. A diesel sample containing the anti-wear agent to be tested was injected into the test oil tank. After the testing machine was started, a high-precision force sensor was used to collect the friction force signal between the friction pairs in real time at a preset sampling frequency. In this embodiment, the sampling frequency was [missing information]. This frequency can capture the dynamic details of the friction process while reducing data redundancy caused by excessively high frequencies.

[0032] Dividing the acquired real-time friction force signal sequence by a constant normal load yields the dimensionless instantaneous friction coefficient value. The instantaneous friction coefficient values ​​at all sampling times are arranged in chronological order to form the original friction coefficient time series, which will be referred to as the original sequence for ease of description. Because in In the experiment, the original friction force signal is easily affected by sensor electronic noise, mechanical vibration, and slow drift caused by temperature changes. Without preprocessing, these interferences will mask the true dynamic characteristics of friction. Therefore, this embodiment performs bandpass filtering on the original sequence to filter out high-frequency electronic noise (such as inherent sensor interference) and low-frequency drift (such as slow changes caused by thermal expansion), ultimately obtaining a friction coefficient time series that reflects the true friction behavior for subsequent dynamic characteristic analysis.

[0033] S2: Reconstruct the phase space of the friction coefficient time series to obtain the state vector characterizing the dynamic evolution of the friction system. The state vector at each moment constitutes the spatial trajectory characterizing the dynamic evolution of the friction system.

[0034] Although the pure friction coefficient time series obtained in step S1 is complete observation data, it is essentially one-dimensional and can only reflect the friction level at each moment, failing to directly reveal the stability changes of the dynamic behavior inside the friction system. To address this issue, this step maps the one-dimensional time series to a high-dimensional phase space and evaluates the macroscopic stability of the friction system by analyzing the geometric distribution of its spatial trajectory.

[0035] Specifically, this embodiment employs the delayed coordinate embedding method to reconstruct the phase space of the pure friction coefficient time series. At any given time... The system's state vector The construction is based on the following principle: combining the friction coefficient value at the current moment with the friction coefficient values ​​at multiple equal time intervals thereafter into a vector.

[0036] Its construction formula is: In the above formula, the meanings of each symbol are as follows: : indicates in The state vector of the friction system at time t, which captures the state vector at that time and thereafter. The friction states at equal time intervals constitute a A point in 3D phase space. : indicates in The coefficient of friction at any given time. : is the embedding dimension, representing the dimension of the reconstructed phase space.

[0037] Based on experience in processing friction signals, and to fully explore the dynamic characteristics of the system while avoiding unnecessary computational complexity, in this embodiment, The preferred value is . : represents the time delay, indicating the interval between adjacent components on the time axis when constructing the state vector. In this embodiment, The value is calculated by signal The autocorrelation function first drops to its initial value The time delay is determined to ensure that the components of each dimension are both correlated and not overly linearly dependent.

[0038] By continuously calculating the state vector at each time step This allows us to obtain a description of the dynamic evolution process of the friction system. 3D space trajectory.

[0039] S3: For any given moment, calculate the phase space dispersion within the analysis time window constructed based on that moment. The phase space dispersion characterizes the dispersion range of the spatial trajectory.

[0040] Calculate the covariance matrix of the point set composed of all state vectors within the analysis time window, and use the logarithm of the determinant of the covariance matrix as the phase space dispersion.

[0041] In this embodiment, the analysis time window is a window of preset length starting from the current time. In this embodiment, the preset length is set to 10 seconds. In other embodiments, it can be adjusted according to the experience of those skilled in the art.

[0042] For any given moment, the formula for calculating the phase space dispersion can be expressed as:

[0043] ;

[0044] In the formula, : Indicates time The phase space dispersion within the analysis time window reflects the time period. The size of the volume occupied by the internal space trajectory in phase space; Indicates the start time of the analysis time window; This indicates the width of the analysis time window; an empirical value is 10 seconds.

[0045] : Indicates within the time window All state vectors within The set of points that constitutes the point set; Represents the computation point set exist Covariance moments in 3D space; This symbol represents the calculation of a determinant. This indicates taking the logarithm of the determinant, used to compress the range of values ​​and make their changes easier to observe.

[0046] Phase space dispersion measures the volume of phase space region explored and covered by the spatial trajectory of a friction system within an analytical time window. When the friction system is in a stable wear stage, its spatial trajectory is constrained within a small volume region, and the phase space dispersion is small and stable. When the friction system tends to become abnormal, such as when the protective film begins to fail, the spatial trajectory becomes disordered and occupies a larger spatial region, thus increasing the phase space dispersion.

[0047] S4: Calculate the abrupt change intensity of the friction coefficient time series. The abrupt change intensity is the product of the degree of deviation of the friction coefficient from its baseline and the instantaneous growth rate.

[0048] The formula for calculating the abrupt change intensity of the friction coefficient time series at any given time is as follows: ;

[0049] In the above formula, the meanings of each symbol are as follows: : indicates in The intensity of the abrupt change at a given time is positively correlated with the magnitude of the upward energy abrupt change at that time. The pure friction coefficient value at any given moment; Indicates in The baseline of the friction coefficient at time t, which is obtained by... The value obtained by applying a long-window moving average filter represents the normal friction level of the friction system at the current stage. In this embodiment, the empirical value of the window length is... seconds, which is 60 seconds in this embodiment; This indicates the degree of deviation of the current friction coefficient from the baseline of the friction coefficient.

[0050] This represents an extremely short time step, equal to the sampling period, for example... Second; It approximates the first derivative of the friction coefficient signal, i.e., the instantaneous growth rate; This represents a maximum value function that ensures only positive deviations and positive rates of change are taken into account.

[0051] It is obtained by multiplying the degree of deviation by the instantaneous growth rate. The degree of deviation is used to calculate the extent to which the current friction value deviates from the baseline of its long-term friction coefficient. The operation only retained friction values ​​that were abnormally high. The instantaneous growth rate term assessed the rate at which the friction value increased within the most recent sampling period. The operation ensures that only moments when the friction value is rapidly increasing are considered. In the formula, if a data point's friction coefficient is higher than the normal baseline and the increase is instantaneous, then the final mutation intensity value will be greater. Therefore, mutation intensity can effectively separate physically significant failure precursors from random, gradually changing background noise.

[0052] S5: Nonlinearly couple phase space dispersion with abrupt change intensity to obtain wear anomaly degree, which is used to characterize the protective performance of anti-wear agent; use the time point when the wear anomaly degree first exceeds the preset threshold as an indicator to evaluate the wear resistance performance of anti-wear agent.

[0053] The overall level of phase space dispersion at each time point is analyzed to obtain the baseline dispersion. For any given time point, the ratio of phase space dispersion to its baseline dispersion is taken as the spatial deviation. The sum of the product of the average value of the mutation intensity in the analysis time window and the preset coupling coefficient and 1 is taken as the adjustment coefficient. The product of the adjustment coefficient and the spatial deviation is taken as the wear anomaly degree.

[0054] The formula for calculating the degree of wear anomaly can be expressed as:

[0055] In the formula, Indicates that in The degree of wear anomaly within the analysis time window starting from the specified value; This indicates the phase space dispersion of the current window; This represents the baseline dispersion. The case where this value is 0 is extremely rare, so we do not consider it here. Of course, during implementation, hyperparameters can be set in the denominator for calculation. In order to avoid the case where the denominator is 0, the average value of the spatial dispersion of each time phase within the preset stable wear stage of the friction and wear test is used as the reference dispersion in this embodiment. The preset stable wear stage can be 2 minutes to 10 minutes after the start of the test. The reference dispersion represents the baseline stability level of the anti-wear agent under normal working conditions. This represents the average mutation intensity at each moment within the analysis time window; it reflects the average intensity and frequency of mutations during that period. This represents a coupling coefficient used to adjust the weight of mutations in the final index. Its empirical value is 50, and in other embodiments it can be determined based on the experience of those skilled in the art.

[0056] If the phase space dispersion only increases briefly without being accompanied by a sustained abrupt change, the wear anomaly will not increase significantly. Similarly, if only an isolated strong abrupt change occurs, but the phase space dispersion of the friction system does not continue to deteriorate, the increase in wear anomaly will also be brief and limited. Only when both deteriorate synchronously and continuously will the wear anomaly exhibit an exponential and irreversible growth trend, thus issuing a high-confidence state transition alarm.

[0057] The time point at which the wear anomaly first exceeds a preset threshold is used as an indicator to evaluate the wear resistance performance of the anti-wear agent.

[0058] In this embodiment, the preset threshold is set to 3. When the wear anomaly first exceeds the preset threshold, the time point is recorded and used as one of the indicators for evaluating the quality of the anti-wear agent, thereby better reflecting the true performance of the anti-wear agent and providing a data basis for the subsequent research and development of anti-wear agents.

[0059] This application also discloses a system for testing the wear resistance of a diesel anti-wear agent, including a processor and a memory. The memory stores computer program instructions, and when the computer program instructions are executed by the processor, a method for testing the wear resistance of a diesel anti-wear agent according to this application is implemented.

[0060] The system also includes other components well known to those skilled in the art, such as communication buses and communication interfaces, the settings and functions of which are known in the art and will not be described in detail here.

[0061] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for testing the wear resistance of a diesel anti-wear agent, characterized in that, include: Obtain the real-time time series of friction coefficients of the friction pair during the friction and wear test; Phase space reconstruction is performed on the friction coefficient time series to obtain the state vector characterizing the dynamic evolution of the friction system. The state vector at each moment constitutes the spatial trajectory characterizing the dynamic evolution of the friction system. For any moment, the phase space dispersion within the analysis time window constructed based on that moment is calculated. The phase space dispersion characterizes the dispersion range of the spatial trajectory. The calculation steps include: calculating the covariance matrix of the point set composed of all state vectors within the analysis time window, and taking the logarithm of the determinant of the covariance matrix as the phase space dispersion. The abrupt change intensity of the friction coefficient time series is calculated. The abrupt change intensity is the product of the degree of deviation of the friction coefficient from its baseline and the instantaneous growth rate. The calculation formula is as follows: ； in, Indicates in The intensity of the sudden change at any given moment; The pure friction coefficient value at any given moment; Indicates in The baseline of the friction coefficient at time t, which is obtained by... The value obtained by applying a long-window moving average filter represents the normal friction level of the friction system at the current stage. This indicates the degree of deviation of the current friction coefficient from the baseline of the friction coefficient. This represents the time step, which is equal to the sampling period; Indicates the instantaneous growth rate; Represent a function that maximizes a value; The phase space dispersion and the abrupt change intensity are nonlinearly coupled to obtain the wear anomaly degree used to characterize the protective performance of the anti-wear agent. The acquisition steps include: analyzing the overall level of phase space dispersion at each time point to obtain the reference dispersion; for any time point, the ratio of phase space dispersion to its reference dispersion is taken as the spatial deviation degree; the sum of the product of the average value of the abrupt change intensity in the analysis time window and the preset coupling coefficient and 1 is taken as the adjustment coefficient; and the product of the adjustment coefficient and the spatial deviation degree is taken as the wear anomaly degree. The time point at which the wear anomaly first exceeds a preset threshold is used as an indicator to evaluate the wear resistance performance of the anti-wear agent.

2. The method for testing the wear resistance of a diesel anti-wear agent according to claim 1, characterized in that, A moving average filter is applied to the time series of friction coefficients to obtain the baseline of the friction coefficients.

3. The method for testing the wear resistance of a diesel anti-wear agent according to claim 1, characterized in that, The window length for the moving average filter is 50 to 70 seconds.

4. The method for testing the wear resistance of a diesel anti-wear agent according to claim 1, characterized in that, The average value of the spatial dispersion of each time phase within the preset stable wear stage of the friction and wear test is used as the reference dispersion.

5. The method for testing the wear resistance of a diesel anti-wear agent according to claim 1, characterized in that, Phase space reconstruction of the friction coefficient time series was performed using the delayed coordinate embedding method.

6. The method for testing the wear resistance of a diesel anti-wear agent according to claim 1, characterized in that, The steps for obtaining the real-time friction coefficient time series of the friction pair during the friction and wear test include: real-time acquisition of the friction force signal between the friction pair, dividing the friction force in the friction force signal by a constant normal load to obtain the instantaneous friction coefficient value at the corresponding moment, arranging the friction coefficient values ​​in chronological order to form the original sequence, and preprocessing the original sequence to obtain the friction coefficient time series.

7. The method for testing the wear resistance of a diesel anti-wear agent according to claim 6, characterized in that, The preprocessing steps for the original sequence include: bandpass filtering the original sequence.

8. A system for testing the wear resistance of a diesel anti-wear agent, characterized in that, include: The processor and memory, wherein the memory stores computer program instructions, which, when executed by the processor, implement a method for testing the wear resistance of a diesel anti-wear agent according to any one of claims 1-7.

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