A method for evaluating lubricating performance of engine oil for hydrogen internal combustion engine

Abstract

This invention discloses a method for evaluating the lubrication performance of engine oil specifically designed for hydrogen internal combustion engines. The method includes: constructing a controllable hydrogen internal combustion engine simulation environment experimental platform; clamping piston rings and cylinder liners onto the platform; adjusting the parameters of the platform to induce reciprocating sliding friction between the piston rings and cylinder liners under hydrogen gas and engine oil lubrication conditions; and analyzing the engine oil lubrication performance between the piston rings and cylinder liners in the hydrogen internal combustion engine based on the friction coefficient measured by the platform. This evaluation method can simulate and control the actual hydrogen gas environment within the cylinder of a hydrogen internal combustion engine and can promptly reflect various parameters of the hydrogen environment.

Description

Technical Field

[0001] This invention belongs to the field of tribology research technology, specifically relating to a method for evaluating the lubrication performance of engine oils for hydrogen internal combustion engines. Background Technology

[0002] In the transportation sector, motor vehicles remain the mainstay of the global transportation system. Traditional automobiles primarily rely on internal combustion engines to burn hydrocarbon fuels, a process that generates a large number of pollutants, including carbon monoxide, carbon dioxide, nitrogen oxides, sulfur oxides, unburned hydrocarbons, smog, particulate matter, and other toxic metals. According to research data from multiple countries, vehicle exhaust emissions have been confirmed as one of the major sources of air pollution. Meanwhile, new energy vehicle technologies, represented by hydrogen energy, are opening up new pathways for global pollutant reduction. Current research on hydrogen fuel cell internal combustion engines mainly focuses on two technical routes: hybrid power systems based on hydrogen-rich fossil fuels and pure hydrogen fuel cell power systems. However, regardless of the technical route adopted, to truly realize the large-scale commercial application of hydrogen fuel cell internal combustion engine vehicles, several key technological bottlenecks still need to be overcome. Among these, the engine durability under special hydrogen-containing operating conditions is particularly critical and requires systematic research.

[0003] To improve the efficiency of internal combustion engines and reduce energy consumption, numerous studies have been conducted worldwide on the anti-wear and friction reduction of various friction pairs, with engine oil lubrication performance being the most extensive area of ​​research. As a key component of the internal combustion engine system, engine oil not only plays a role in cooling, cleaning, and sealing, but its excellent lubrication performance can also significantly improve the system's wear resistance and service life. With the advancement of hydrogen fuel cell internal combustion engines, the operating environment of various systems must consider the influence of hydrogen, requiring the redesign of key systems such as the combustion system, injection and ignition system, turbocharging system, and exhaust aftertreatment system. Simultaneously, the lubrication system may contain a certain amount of hydrogen, which will participate in the lubrication process of the engine oil and affect its overall lubrication effect to some extent. Therefore, although the use of hydrogen fuel can significantly reduce environmental pollution, the performance of internal engine components also needs corresponding improvements, a crucial aspect to consider during the development of new internal combustion engines. Against the backdrop of rapid development in energy-saving and emission-reduction technologies, the development of internal combustion engine lubricants adapted to the hydrogen environment has become particularly important, and the existing lubricant evaluation system urgently needs adjustment to adapt to new technological requirements.

[0004] To further evaluate the frictional characteristics of various friction pairs and the lubrication performance of engine oil in a hydrogen environment, it is essential to accurately simulate the frictional conditions in a hydrogen environment. Previous research has provided valuable experimental data and a solid foundation for this research. For example, some teams, using ZrO2 as a friction pair material in conjunction with DLC films to achieve ultra-low friction, conducted corresponding frictional experiments in various gas environments, including hydrogen. The results showed that the ultra-low friction of the friction pair is closely related to hydrogen. In 2021, a team investigated the interaction between external and internal hydrogen on the contact surfaces in the "cylinder block-piston ring" frictional coupling. The experimental results showed that removing hydrogen from the piston rings can reduce the structural heterogeneity, residual stress, and uneven physicochemical properties of the friction pair surface, thereby reducing stress concentration and improving the frictional properties of spark-ignition engines. Similarly, some scholars have conducted a comparative study on the lubrication performance of various hydrogen-containing emulsified engine oils. In the experiment, hydrogen, engine oil, and water were mixed in a high-temperature and high-pressure resistant metal container to simulate the actual situation of engine oil emulsification in a hydrogen internal combustion engine under hydrogen conditions.

[0005] Studies have shown that although scholars at home and abroad have made phased progress in exploring the tribological behavior mechanism and constructing lubrication performance evaluation methods in hydrogen environments, there are still several key problems to be solved in the existing technical system. Although the existing various engine oil performance testing and evaluation methods play an important role, they still have the following limitations: (1) They have failed to effectively construct a simulation system of the unique combustion environment in the cylinder of hydrogen internal combustion engines (gas composition, load, humidity, etc.); (2) They lack the ability to simulate the differences in different friction forms (including point contact, line contact and reciprocating motion) in hydrogen environments; (3) They lack the means to dynamically mix the hydrogen-lubricating oil two-phase system and accurately control the gas ratio; (4) They have not yet established a complete analytical framework for the evolution of tribological performance caused by hydrogen environments and a research system for the mechanism of action. These factors restrict the accuracy and universality of engine oil performance evaluation results in hydrogen environments. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method for evaluating the lubrication performance of engine oils specifically designed for hydrogen internal combustion engines. This method can simulate and control the actual hydrogen environment inside the cylinder of a hydrogen internal combustion engine and can reflect various parameters of the hydrogen environment in a timely manner.

[0007] To achieve the above objectives, the present invention adopts the following specific technical solution:

[0008] This invention provides a method for evaluating the lubrication performance of engine oils specifically designed for hydrogen internal combustion engines. The evaluation method includes the following steps: Step 1: Build a controllable hydrogen internal combustion engine simulation environment test platform. This controllable hydrogen internal combustion engine simulation environment test platform is used to simulate the working conditions of piston rings and cylinder liners of hydrogen internal combustion engines. Step 2: Clamp the piston rings and cylinder packing onto the controlled hydrogen internal combustion engine simulation environment test platform; Step 3: Adjust the parameters of the controllable hydrogen internal combustion engine simulation environment test platform to make the piston rings and cylinder liners reciprocate sliding friction under hydrogen environment and engine oil lubrication. Step four: Based on the friction coefficient measured by the controlled hydrogen internal combustion engine simulation environment test platform, analyze the oil lubrication performance between the piston rings and cylinder liners in the hydrogen internal combustion engine.

[0009] Furthermore, the controllable hydrogen internal combustion engine simulation environment test platform built in step one includes a friction and wear test machine, a gas environment chamber, a hydrogen supply system, a water supply system, a lubrication system, and a central control system; The friction and wear testing machine includes a worktable, a drive device, and a transmission rod located on top of the worktable; the worktable is used to fix the gas environment chamber and the cylinder liner; the cylinder liner is located inside the gas environment chamber; the drive device is used to drive the transmission rod to reciprocate in the vertical direction; the piston ring is fixedly installed at the bottom end of the transmission rod to realize the sliding friction between the piston ring and the cylinder liner; A sealed space is formed between the gas environment chamber and the workbench, and the oil is contained therein. The transmission rod and the gas environment chamber are dynamically sealed together. The hydrogen supply system is used to deliver hydrogen to the engine oil in the gas environment chamber. The water supply system is used to deliver water or water vapor into the engine oil, using water or water vapor to simulate the products of hydrogen combustion; The lubrication system is used to provide oil to the friction surfaces of the piston rings and the cylinder liner for lubrication; The central control system is used to control the hydrogen supply system, the water supply system, and the lubrication system.

[0010] Furthermore, the gas environment chamber includes a chamber body, a dynamic sealing membrane, an air inlet pipe, a heating device, a temperature sensor, a humidity sensor, and a hydrogen sensor; The chamber is a cylindrical body with openings at both ends. The bottom end is fixedly installed on the top surface of the workbench, and the top end is sealed with the dynamic sealing film, thereby forming a sealed space between the workbench, the chamber and the dynamic sealing film. The dynamic sealing film is dynamically sealed to the transmission rod; The air intake pipe penetrates the side wall of the cylinder, one end of which is connected to the hydrogen supply system and the water supply system, and the other end is located at the bottom of the chamber and is provided with multiple small holes for supplying hydrogen and water or water vapor to the engine oil. The heating device is fixedly installed on the cylinder and is used to heat the engine oil; The temperature sensor is used to detect the engine oil temperature in real time; The humidity sensor is used to detect the humidity inside the cabin in real time; The hydrogen sensor is used to monitor the hydrogen concentration inside the cabin in real time. The central control system is connected to the heating device, the temperature sensor, the humidity sensor, and the hydrogen sensor, and is used to control the heating device.

[0011] Furthermore, the hydrogen supply system includes a hydrogen cylinder or hydrogen production device, a pressure reducing valve, a shut-off valve, a check valve, a pressure gauge, and a mass flow controller; The outlet of the hydrogen cylinder or the hydrogen production device is connected to the inlet pipe through a pipeline, and the pressure reducing valve, the shut-off valve, the check valve, the pressure gauge and the mass flow controller are installed in sequence in the pipeline. The mass flow controller is used to control the mass flow rate of hydrogen. The central control system regulates the hydrogen concentration by controlling the shut-off valve and the mass flow controller.

[0012] Furthermore, the cabin is also equipped with an exhaust port that can be opened and closed, and an exhaust pipe connected to the exhaust port; The exhaust pipe is equipped with a filter, and the other end of the exhaust pipe extends outdoors.

[0013] Furthermore, the controllable hydrogen internal combustion engine simulation environment test platform also includes a security system to maintain the safety of the test environment; The security system includes an exhaust hood, an audible and visual alarm, a gas sensor, and an explosion-proof fan; The exhaust hood is installed on top of the friction and wear testing machine; The audible and visual alarm, the gas sensor, and the explosion-proof fan are all connected to the central control system.

[0014] Furthermore, the gas environment chamber also includes a pressure sensor installed inside the chamber, which is used to monitor the gas pressure inside the chamber in real time and is connected to the central control system.

[0015] Furthermore, the lubrication system includes an oil pump, an oil inlet pipe, and an oil outlet pipe; Both the oil inlet pipe and the oil outlet pipe are installed through the side wall of the cylinder body. Both the oil inlet pipe and the oil outlet pipe are connected to the oil pump and are used to spray engine oil to the top of the cylinder liner through the oil pump.

[0016] Furthermore, the central control system adopts a PLC measurement and control system.

[0017] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: 1. Based on multi-dimensional evaluation indicators, the evaluation method of this invention constructs a complete in-cylinder lubrication performance testing and evaluation system for hydrogen internal combustion engines. It can simulate the hydrogen environment required by hydrogen internal combustion engines and systematically evaluate the comprehensive lubrication performance of different lubricating oils under the working environment of hydrogen internal combustion engines.

[0018] 2. The evaluation method of the present invention can simulate the hydrogen environment required by a hydrogen internal combustion engine, simulate the working conditions of the piston rings and cylinder liners of a hydrogen internal combustion engine, and can meet diverse experimental needs, such as simulating the combustion chamber environment of a conventional hydrogen internal combustion engine or conditions under specific hydrogen concentrations.

[0019] 3. The evaluation method of the present invention can achieve full gas-liquid mixing. Multiple small holes are set on the air inlet pipe to ensure that hydrogen and / or water vapor are fully mixed with engine oil, which effectively improves the uniformity and stability of hydrogen components and reduces the error caused by uneven mixing in the experiment.

[0020] 4. The evaluation method of this invention can adjust humidity and temperature, enabling the experimental platform to achieve precise control of oil humidity and temperature. This is particularly important for conducting friction experiments under simulated internal environmental conditions of a specific hydrogen internal combustion engine, ensuring the repeatability and accuracy of the experimental results.

[0021] 5. The evaluation method of this invention utilizes a PLC (Programmable Logic Controller) measurement and control system to achieve real-time monitoring. By using the PLC measurement and control system, real-time monitoring and precise control of the working environment can be achieved. This real-time monitoring system not only improves the degree of automation, but also responds to and adjusts environmental parameters in a timely manner, ensuring the stability and safety of the experimental process.

[0022] 6. The evaluation method of this invention has good versatility and adaptability, and can accommodate the experimental requirements of different friction forms (such as point contact friction, line contact friction, and surface contact friction). Through a modular design concept, this evaluation method only requires appropriate parameter adjustments and equipment adaptation to achieve seamless integration with various mainstream friction and wear testing machines, ensuring the portability of the testing scheme and the comparability of results on different experimental platforms. This flexibility enables the method to meet diverse scientific research needs and engineering application scenarios. Attached Figure Description

[0023] Figure 1 This is a flowchart of the method for evaluating the lubrication performance of engine oil for hydrogen internal combustion engines according to the present invention; Figure 2 A schematic diagram of the experimental platform for simulating the environment of a controllable hydrogen internal combustion engine; Figure 3 This is a schematic diagram of the gas environment chamber. Figure 4The images show the 2D / 3D morphology of a test sample under different oil and hydrogen environments. Figure 5 SEM images of a test sample under different oil and hydrogen environments; Figure 6 The content of zinc on the wear surface of a test sample under different oil samples and different concentrations of hydrogen; Figure 7 The content of sulfur on the wear surface of a test sample under different oil samples and different concentrations of hydrogen; Figure 8 The content of phosphorus on the wear surface of a test sample under different oil samples and different concentrations of hydrogen. Figure 9 This refers to the iron content on the wear surface of a test sample under different oil samples and hydrogen concentrations.

[0024] Figure label: 1-Friction and wear testing machine, 2-Gas environment chamber, 3-Hydrogen supply system, 4-Water supply system, 5-Lubrication system, 6-Central control system, 11-Transmission rod, 21-Chamber body, 22-Dynamic sealing membrane, 23-Inlet pipe, 71-Exhaust hood, 72-Audible and visual alarm, 73-Gas sensor, 74-Explosion-proof fan. Detailed Implementation

[0025] 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 embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1 This invention provides a method for evaluating the lubrication performance of engine oils specifically designed for hydrogen internal combustion engines, such as... Figure 1 As shown, the evaluation method includes the following steps: Step 1: Construct a controllable hydrogen internal combustion engine simulation environment test platform. This platform is used to simulate the working conditions of piston rings and cylinder liners in a hydrogen internal combustion engine; the test samples are piston rings and cylinder liners; for example... Figure 2 and Figure 3As shown, the constructed controllable hydrogen internal combustion engine simulation environment experimental platform includes a friction and wear testing machine 1, a gas environment chamber 2, a hydrogen supply system 3, a water supply system 4, a lubrication system 5, and a central control system 6. The friction and wear testing machine 1 includes a workbench, a drive unit, and a transmission rod 11 located on top of the workbench. The workbench is used to fix the gas environment chamber 2 and the cylinder liner. The cylinder liner is located inside the gas environment chamber 2. The drive unit is used to drive the transmission rod 11 to reciprocate vertically. A piston ring is fixedly installed at the bottom end of the transmission rod 11 to achieve sliding friction between the piston ring and the cylinder liner. A sealed space is formed between the gas environment chamber 2 and the workbench, containing engine oil. A dynamic seal is present between the transmission rod 11 and the gas environment chamber 2. The hydrogen supply system 3 is used to supply hydrogen to the engine oil in the gas environment chamber 2. The water supply system 4 is used to supply water or water vapor to the engine oil, simulating the products of hydrogen combustion. The lubrication system 5 is used to provide engine oil to the friction surfaces of the piston ring and the cylinder liner for lubrication. The central control system 6 is used to control the hydrogen supply system 3, the water supply system 4, and the lubrication system 5. The central control system 6 adopts a PLC measurement and control system.

[0027] Step 2: Clamp the piston rings and cylinder packing onto the controlled hydrogen internal combustion engine simulation environment test platform; Step 3: Adjust the parameters of the controllable hydrogen internal combustion engine simulation environment test platform to make the piston rings and cylinder liners reciprocate sliding friction under hydrogen environment and engine oil lubrication. Step four: Based on the friction coefficient measured by the controlled hydrogen internal combustion engine simulation environment test platform, analyze the oil lubrication performance between the piston rings and cylinder liners in the hydrogen internal combustion engine.

[0028] In the aforementioned controlled hydrogen internal combustion engine simulation environment experimental platform, such as Figure 3As shown, the gas environment chamber 2 includes a chamber body 21, a dynamic sealing membrane 22, an air inlet pipe 23, a heating device, a temperature sensor, a humidity sensor, a hydrogen sensor, and a pressure sensor. The chamber body 21 is a cylindrical body open at both ends, with its bottom fixedly mounted on the top surface of the workbench and the top sealed with the dynamic sealing membrane 22, thus forming a sealed space between the workbench, the chamber body 21, and the dynamic sealing membrane 22. The dynamic sealing membrane 22 dynamically seals against the transmission rod 11. The air inlet pipe 23 penetrates the side wall of the cylinder, with one end connected to the hydrogen supply system 3 and the water supply system 4, and the other end located at the bottom of the chamber body 21 with multiple small holes for supplying hydrogen and water or water vapor to the engine oil. The heating device is fixedly mounted on the cylinder for heating the engine oil. The temperature sensor is used to detect the engine oil temperature in real time. The humidity sensor is used to detect the humidity inside the chamber body 21 in real time. The hydrogen sensor is used to monitor the hydrogen concentration inside the chamber body 21 in real time. The central control system 6 is connected to the heating device, temperature sensor, humidity sensor, and hydrogen sensor to control the heating device. A pressure sensor is installed inside the chamber 21 to monitor the gas pressure inside the chamber in real time and is connected to the central control system 6. The chamber 21 is also equipped with an on / off exhaust port and an exhaust pipe connected to the exhaust port; a filter is installed in the exhaust pipe, and the other end of the exhaust pipe extends to the outside.

[0029] The hydrogen supply system 3 includes a hydrogen cylinder or hydrogen production device, a pressure reducing valve, a shut-off valve, a check valve, a pressure gauge, and a mass flow controller; the outlet of the hydrogen cylinder or hydrogen production device is connected to the inlet pipe 23 through a pipeline, and the pressure reducing valve, shut-off valve, check valve, pressure gauge, and mass flow controller are installed sequentially in the pipeline; the mass flow controller is used to control the mass flow rate of hydrogen; the central control system 6 adjusts the hydrogen concentration by controlling the shut-off valve and the mass flow controller.

[0030] The aforementioned lubrication system 5 includes an oil pump, an oil inlet pipe, and an oil outlet pipe; both the oil inlet pipe and the oil outlet pipe are installed through the side wall of the cylinder body, and both the oil inlet pipe and the oil outlet pipe are connected to the oil pump for spraying engine oil to the top of the cylinder liner through the oil pump.

[0031] To ensure the safety of the experiment, the controllable hydrogen internal combustion engine simulation environment experimental platform also includes a security system for maintaining the safety of the experimental environment; the security system includes an exhaust hood 71, an audible and visual alarm 72, a gas sensor 73, and an explosion-proof fan 74; the exhaust hood 71 is installed on top of the friction and wear testing machine 1; the audible and visual alarm 72, the gas sensor 73, and the explosion-proof fan 74 are all connected to the central control system 6.

[0032] The aforementioned evaluation method also integrates exhaust gas emission and safety systems, which can effectively treat the exhaust gas generated during the experiment, achieve harmless treatment of the experimental gas, and meet environmental protection requirements.

[0033] Example 2 The detailed description of the lubrication performance evaluation method for special engine oil for hydrogen internal combustion engines in the embodiments of the present invention mainly includes six steps: determining the test scheme and related parameters, building a controllable hydrogen internal combustion engine simulation environment test platform, engine oil lubrication friction test under hydrogen internal combustion engine environment, multi-dimensional data analysis of tribological behavior, in-depth mechanism study of gas-surface interaction, and integrating test results for overall evaluation.

[0034] The specific process is as follows: 1. Determine the test plan and related parameters: Taking the actual working conditions of the hydrogen internal combustion engine as the test background, systematically sort out the experimental test plan and specific experimental parameters, such as hydrogen concentration, humidity, flow rate, friction load, frequency, time, etc.

[0035] 2. Establish a controllable hydrogen internal combustion engine simulation environment experimental platform: The experimental platform is systematically designed based on the requirements of simulating the actual hydrogen environment of a hydrogen internal combustion engine and constructing a tribological experimental system. The type of test oil, friction type (point contact friction, linear friction, and reciprocating friction, etc.), gas composition and proportion are determined, and the entire system is integrated with the required friction and wear testing machine 1.

[0036] This step is the core step. The controlled hydrogen internal combustion engine simulation environment test platform should include the following parts: friction and wear test machine 1, gas environment chamber 2, hydrogen supply system 3, water supply system 4, lubrication system 5, central control system 6, and security system.

[0037] The friction and wear testing machine 1 includes a worktable, a drive unit, and a transmission rod 11. The worktable is used to fix the gas environment chamber 2 and the cylinder liner. The bottom of the gas environment chamber 2 is sealed and mounted on the worktable. The cylinder liner is fixedly mounted on the worktable by a clamp and located inside the gas environment chamber 2. The drive unit drives the transmission rod 11 to reciprocate vertically. A piston ring is fixedly mounted at the bottom end of the transmission rod 11 to achieve sliding friction between the piston ring and the cylinder liner. The gas environment chamber 2 is located on top of the worktable, forming a sealed space between the gas environment chamber 2 and the worktable, and is filled with engine oil. A dynamic seal is maintained between the transmission rod 11 and the gas environment chamber 2, ensuring that the gas environment chamber 2 remains sealed when the drive unit drives the transmission rod 11. A hydrogen supply system 3 supplies hydrogen to the engine oil inside the gas environment chamber 2 to simulate hydrogen, the fuel used in a hydrogen internal combustion engine. Water supply system 4 is used to supply water or water vapor to the engine oil, simulating the products of hydrogen combustion, which occurs in hydrogen internal combustion engines. Lubrication system 5 provides engine oil to the friction surfaces of the piston rings and cylinder liners for lubrication. Central control system 6 controls hydrogen supply system 3, water supply system 4, and lubrication system 5. Central control system 6 employs a PLC (Programmable Logic Controller) monitoring and control system. By using the PLC monitoring and control system, real-time monitoring and precise control of the gas environment can be achieved, not only improving the automation level of the experimental setup but also enabling immediate response and adjustment of environmental parameters, thereby ensuring the stability and safety of the experimental process. This real-time monitoring system not only makes operation more efficient but also significantly improves the accuracy of experimental data and the controllability of experimental conditions.

[0038] The hydrogen supply system 3 includes a hydrogen cylinder or hydrogen production device, a pressure reducing valve, a shut-off valve, a check valve, a pressure gauge, and a mass flow controller. The outlet of the hydrogen cylinder or hydrogen production device is connected to the inlet pipe 23 via a pipeline, and the pressure reducing valve, shut-off valve, check valve, pressure gauge, and mass flow controller are installed sequentially in the pipeline. The mass flow controller is used to control the mass flow rate of hydrogen. The central control system 6 adjusts the hydrogen concentration by controlling the shut-off valve and the mass flow controller. To simulate different gas environments, the composition of the gas environment can be changed by replacing the hydrogen cylinder or adding other gas cylinders. At the same time, the gas flow rate can be controlled by the mass flow rate to simulate the concentration of different gases. A small hole is punched at the end of the inlet pipe 23 to achieve thorough gas-liquid mixing.

[0039] The gas environment test chamber is a key component of this controllable hydrogen internal combustion engine simulation environment test platform. The gas environment chamber 2 includes a chamber body 21, a dynamic sealing membrane 22, an intake pipe 23, a heating device, a temperature sensor, a humidity sensor, a hydrogen sensor, and a pressure sensor. The chamber body 21 is a cylindrical body open at both ends, with its bottom fixed to the top surface of the workbench and the top sealed with the dynamic sealing membrane 22, thus forming a sealed space between the workbench, the chamber body 21, and the dynamic sealing membrane 22. The dynamic sealing membrane 22 dynamically seals against the transmission rod 11. Made of high-strength rubber, the dynamic sealing membrane 22 can withstand the gas pressure inside the gas environment chamber 2. The dynamic sealing membrane 22, sealing the top of the gas environment chamber 2, ensures the airtightness of the chamber while maximizing the flexibility of the friction experiment without affecting the movement of the piston rings inside the chamber.

[0040] An intake pipe 23 penetrates the side wall of the cylinder, with one end connected to the hydrogen supply system 3 and the water supply system 4, and the other end located at the bottom of the chamber 21 with multiple small holes for supplying hydrogen and water or water vapor to the engine oil. Adding water or water vapor to the engine oil simulates the real operating conditions of a hydrogen internal combustion engine. A heating device is fixedly installed in the cylinder to heat the engine oil, simulating the oil heating up during hydrogen internal combustion engine operation. The heating device consists of heating elements / heating rods. A temperature sensor is used to detect the engine oil temperature in real time. A humidity sensor is used to detect the humidity inside the chamber 21 in real time. A hydrogen sensor is used to monitor the hydrogen concentration inside the chamber 21 in real time. The central control system 6 is connected to the heating device, temperature sensor, humidity sensor, and hydrogen sensor to control the heating device. A pressure sensor is installed inside the chamber 21 to monitor the gas pressure inside the chamber 21 in real time and is connected to the central control system 6. The chamber 21 also has an on / off exhaust port and an exhaust pipe connected to the exhaust port; a filter is installed in the exhaust pipe, and the other end of the exhaust pipe extends to the outside. The function of the exhaust vent in the gas environment chamber 2 is to expel accumulated waste gases from the laboratory, ensuring that the air inside the chamber remains fresh and has a suitable gas composition. The exhaust vent is typically connected to an external system or filter via an exhaust duct to effectively remove harmful substances and maintain the safety and stability of the experimental environment.

[0041] The monitoring components of Gas Environment Chamber 2 mainly include temperature sensors, humidity sensors, hydrogen sensors, and pressure sensors. The temperature sensor in Gas Environment Chamber 2 monitors and records internal temperature changes in real time, helping to ensure the experimental environment remains within the predetermined temperature range. The pressure sensor in Gas Environment Chamber 2 detects and records internal gas pressure changes in real time, helping to monitor and maintain the pressure level of the gas within the laboratory. The hydrogen sensor in Gas Environment Chamber 2 monitors and measures changes in hydrogen concentration, providing real-time hydrogen concentration data to help researchers control and adjust the composition of the gas within the laboratory. The humidity sensor in Gas Environment Chamber 2 monitors and measures changes in humidity levels in the experimental environment, providing accurate humidity data to help researchers control and maintain humidity conditions within the laboratory.

[0042] The safety system includes an exhaust hood 71, an audible and visual alarm 72, a gas sensor 73, and an explosion-proof fan 74. The exhaust hood 71 is installed on top of the friction and wear testing machine 1. The audible and visual alarm 72, the gas sensor 73, and the explosion-proof fan 74 are all connected to the central control system 6. The safety system can discharge toxic gases in the event of a gas leak, ensuring the safety of the experiment.

[0043] 3. Oil lubrication friction test under hydrogen internal combustion engine environment: According to the target working condition (such as the combustion chamber environment of hydrogen internal combustion engine), the mixed gas (such as H2-O2-H2O ternary system) is accurately proportioned. The partial pressure and flow rate of hydrogen are controlled by the mass flow controller to ensure that the hydrogen concentration error is ≤1.5%. Different forms of friction tests are carried out on the multi-functional friction and wear testing machine 1, and the friction coefficient and transient fluctuations are collected simultaneously.

[0044] 4. Multi-dimensional Data Analysis of Tribological Behavior: Statistical analysis using multiple sets of friction coefficient data reveals the evolution law of oil lubrication under the in-cylinder combustion environment of hydrogen internal combustion engines and provides a theoretical basis for subsequent research. A comparative analysis of the friction data of various oil samples is conducted. In tribological research, the friction coefficient is a key measure of frictional resistance and is crucial for evaluating the effectiveness of lubricating oil. It reflects the force between the friction pair formed by the piston ring and cylinder liner, and is affected by material properties and lubricating oil performance. High-quality lubricating oil can effectively reduce the friction coefficient and decrease resistance. Measuring the friction coefficient under different conditions using a friction and wear testing machine allows for understanding the performance of lubricating oil and provides a basis for formula optimization. This data is very important for selecting lubricating oils suitable for different application scenarios and improving equipment efficiency. In summary, evaluating and characterizing tribological behavior using friction coefficient-related data is an intuitive and effective method. Specific indicators can be referenced in the following examples: Firstly, friction coefficient curves or bar charts with error bars can be used to represent the friction coefficients and observe the percentage increase in friction coefficients between different control groups. The coefficient of variation (fluctuation effect) of friction coefficients in different control groups can also be observed to specifically evaluate the quality of friction behavior. When operating condition I changes to operating condition II, the average friction coefficient of oil sample A increases from 0.1118 to 0.1209 (relative increase of 8.1%), and its coefficient of variation (CV) increases from 7.9% to 66.5%. The average friction coefficient of oil sample B increases from 0.1193 to 0.1268 (relative increase of 6.3%), and its coefficient of variation (CV) increases from 8.1% to 42.9%. This preliminarily indicates that oil sample B is more adaptable to the environment of operating condition II than oil sample A.

[0045] 5. In-depth study of the mechanism of gas-surface interaction: A combination of ultra-depth-of-field microscopy and scanning electron microscopy (SEM) is used to analyze the morphology of wear tracks. X-ray photoelectron spectroscopy (XPS) is employed to obtain the elemental distribution and chemical valence state evolution of the tribochemical reaction film. Alternatively, molecular dynamics simulations are used to study the interaction mechanism between lubricant molecules, additives, and the friction pair surface at the atomic scale, elucidating the formation and failure mechanism of boundary films in complex gas environments. These methods allow for a comprehensive analysis and evaluation of friction experiment results, revealing the mechanism and underlying principles of the gas environment's influence on tribological behavior.

[0046] like Figure 4 and Figure 5 As shown in the morphology diagram, the changes in wear track morphology of the oil sample under various hydrogen environmental conditions can be observed, with condition I showing better results compared to condition II. Furthermore, the collected wear track depth data can be compared with those from bench experiments; if the trends are similar, the reliability of the experimental design can be verified.

[0047] Figure 6 The content of zinc on the wear surface of a test sample under different oil samples and different concentrations of hydrogen; Figure 7 The content of sulfur on the wear surface of a test sample under different oil samples and different concentrations of hydrogen; Figure 8 This refers to the phosphorus content on the wear surface of a test sample under different oil samples and hydrogen concentrations.

[0048] like Figure 9 As shown in the XPS elemental analysis chart, Condition I and Condition II represent different combustion environments in a hydrogen internal combustion engine. Furthermore, the content of each element decreases in Condition II, indicating a decline in the ability of surface elements to form films. This environment has a negative impact on lubrication.

[0049] 6. Integrate test results and conduct an overall evaluation: Summarize and analyze the obtained multivariate data to comprehensively consider the lubrication performance of different oils in the hydrogen environment inside the cylinder of a hydrogen internal combustion engine. Specific indicators are as follows: (1) Stability of friction coefficient: Within the typical operating concentration range of hydrogen internal combustion engines (hydrogen environment), the friction coefficient needs to maintain good stability. The coefficient of variation of the friction coefficient should be controlled within a certain range (30%), which means that the fluctuation range of the friction coefficient is relatively small and the lubrication state is stable.

[0050] (2) Morphological characteristics of wear tracks: The surface of the wear track should exhibit low wear and good structural integrity. The depth of the wear track should be as small as possible, indicating minimal material loss. Significant large-area spalling should not occur on the surface of the wear track. Spalling indicates material failure and insufficient lubrication film protection.

[0051] (3) Surface elements and boundary film quality (core indicators): A high-quality, stable, and effective frictional protective boundary film must be formed on the wear surface. The content of key elements (especially active elements such as P and S) in the boundary film must be sufficient and uniformly distributed on the friction surface. Key elements (P, S, etc.) must be in a chemical valence state that is conducive to lubrication protection (e.g., forming frictional reaction films such as metal sulfides). The boundary film structure should be dense and continuous, avoiding loose and discontinuous structures. The boundary film must be able to remain stable under changes in hydrogen concentration and high humidity / water environment generated by hydrogen combustion, and should not be easily damaged or disturbed.

[0052] The detailed process of evaluating the lubrication performance of hydrogen internal combustion engine oil using the above evaluation method is as follows: Before conducting friction experiments to evaluate the lubrication performance of hydrogen-powered internal combustion engine oils, ensuring the accuracy of the simulated hydrogen environment is crucial. First, a detailed study of the required hydrogen concentration is necessary, including the proportion and concentration range of hydrogen, as well as temperature and humidity conditions that may affect the experimental results. Accurate setting of these parameters is essential for the repeatability and accuracy of the experimental results. Selecting suitable hydrogen cylinders and a hydrogen generator is the first step. Different types of cylinders can be prepared to hold different gas compositions as needed. Each cylinder must be equipped with pressure reducing valves, shut-off valves, and other devices to ensure safe control of gas release and flow rate. Furthermore, the parameters of the mass flow controller need to be preset to precisely control the gas flow rate and concentration according to the experimental design.

[0053] After preparing the hydrogen supply system 3, ensuring its stability and reliability is crucial. First, all components of the monitoring and control system need careful inspection, including the PLC control system, temperature sensors, and heating devices. The PLC (Programmable Logic Controller) control system is responsible for monitoring and adjusting various parameters during the experiment, such as gas pressure, flow rate, and environmental conditions, ensuring the accuracy and safety of the experiment. By executing pre-set programs and logic, the PLC control system can respond promptly to any potential anomalies, thereby protecting the experimental equipment and personnel. Simultaneously, the proper functioning of pressure gauges and concentration meters is also essential. Pressure gauges monitor the pressure in the gas cylinders, and pressure sensors detect the pressure inside the gas environment chamber 2, ensuring operation within safe limits. Hydrogen sensors detect the hydrogen concentration inside the gas environment chamber 2 and, via concentration meters, measure and record the concentrations of other gas components, ensuring that the gases used in the experiment meet predetermined parameter requirements. These measuring devices must be calibrated and verified to ensure their accuracy and reliability.

[0054] In addition, inspection, testing, and venting are equally important. The venting system, consisting of vents and ductwork, is responsible for effectively removing waste gases and residual gases generated during the experiment, preventing them from interfering with experimental results or adversely affecting the environment. It is essential to ensure that the venting system's ductwork is unobstructed, valves operate correctly, and waste gases are effectively discharged as needed.

[0055] After a series of preparatory steps, the test oil sample is added to the gas environment chamber 2, and the top of the chamber is sealed with a plastic film. This step is to ensure the airtightness of the experimental environment. The sealing operation should be carried out carefully to prevent gas leakage or interference from external environmental factors on the experimental results.

[0056] After confirming the overall airtightness of the equipment, hydrogen is injected into the gas environment chamber 2. During this process, the readings of the PLC control system, pressure gauge, and concentration meter must be closely monitored. The PLC control system is responsible for monitoring and adjusting the hydrogen flow rate and pressure to ensure that the experimental conditions meet the preset requirements. The pressure gauge is used to ensure that the gas pressure is within a safe range and to promptly detect any abnormalities. The concentration meter is used to monitor the composition of the gas mixture to ensure that the required hydrogen concentration reaches the expected level. Once the hydrogen reaches the preset concentration and pressure, the hydrogen cylinder is promptly shut off, and preparation for the friction experiment begins. Throughout the experiment, continuous monitoring of the data changes in the monitoring system is essential to ensure the stability of the experiment and the accuracy of the data.

[0057] After the friction experiment, the gas in the gas environment chamber 2 must first be effectively vented through the exhaust hood 71. The venting process must continue until all gas is completely exhausted to ensure a safe and clean experimental environment. Once it is confirmed that the gas has been completely removed, the plastic film can be opened, and the piston rings and cylinder liners can be removed for inspection. The inspection process requires careful observation of the friction surfaces to assess their frictional damage. This includes checking for possible wear, deformation, or other surface changes, which will provide important information about frictional performance and durability. After removing the friction components, further analysis and measurements are required, such as using a microscope to examine microscopic surface features or conducting physical property tests. These analyses will help to gain a deeper understanding of the friction experiment results and verify the effectiveness and accuracy of the experimental design.

[0058] The aforementioned evaluation method employs multivariate data analysis technology to conduct multi-dimensional performance evaluations of engine oil samples under simulated hydrogen internal combustion engine gas environments. By accurately simulating key parameters of actual operating conditions, it ensures a high degree of consistency between experimental conditions and real-world operating environments, thereby obtaining test results with engineering guidance significance. This evaluation method not only achieves controllable adjustment of experimental environmental parameters but also accurately reflects the performance of engine oil in actual hydrogen internal combustion engine environments, providing reliable data support for the research and development and application of specialized oils.

[0059] Obviously, those skilled in the art can make various modifications and variations to the embodiments of the present invention without departing from the spirit and scope of the invention. Therefore, if these modifications and variations fall within the scope of the claims of the present invention and their equivalents, the present invention also intends to include these modifications and variations.

[0060] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for evaluating lubricating properties of engine oil for hydrogen internal combustion engines, characterized by, The method comprises the following steps: Step one, a controllable hydrogen internal combustion engine simulation environment experimental platform is built, which is used to simulate the working condition of the piston ring and the cylinder sleeve of the hydrogen internal combustion engine; Step two, the piston ring and the cylinder sleeve are clamped on the controllable hydrogen internal combustion engine simulation environment experimental platform; Step three, the parameters of the controllable hydrogen internal combustion engine simulation environment experimental platform are adjusted, so that the piston ring and the cylinder sleeve reciprocate and slide in the hydrogen environment and the oil lubrication condition; Step four, according to the friction coefficient measured by the controllable hydrogen internal combustion engine simulation environment experimental platform, the oil lubrication performance between the piston ring and the cylinder sleeve in the hydrogen internal combustion engine is analyzed.

2. The method for evaluating lubricating properties of engine oil for hydrogen internal combustion engine according to claim 1, characterized by, The controllable hydrogen internal combustion engine simulation environment experimental platform built in step one comprises a friction and wear testing machine, a gas environment cabin, a hydrogen supply system, a water supply system, a lubricating system and a central control system; The friction and wear testing machine comprises a workbench, a driving device and a transmission rod located on the top of the workbench; the workbench is used to fixedly install the gas environment cabin and the cylinder sleeve; the cylinder sleeve is located in the gas environment cabin; the driving device is used to drive the transmission rod to reciprocate in the vertical direction; the bottom end of the transmission rod is fixedly installed with the piston ring, which is used to realize the sliding friction between the piston ring and the cylinder sleeve; A sealed space is formed between the gas environment cabin and the workbench, and the oil is accommodated therein; The transmission rod is dynamically sealed with the gas environment cabin; The hydrogen supply system is used to deliver hydrogen into the oil in the gas environment cabin; The water supply system is used to deliver water or water vapor into the oil, so as to simulate the product of hydrogen combustion by the water or water vapor; The lubricating system is used to provide oil to the friction surface between the piston ring and the cylinder sleeve for lubrication; The central control system is used to control the hydrogen supply system, the water supply system and the lubricating system.

3. The method for evaluating lubricating properties of engine oil for hydrogen internal combustion engine according to claim 2, characterized by, The gas environment cabin comprises a cabin body, a dynamic sealing film, an air inlet pipe, a heating device, a temperature sensor, a humidity sensor and a hydrogen sensor; The cabin body is a cylinder with both ends open, which is fixedly installed on the top surface of the workbench at the bottom end and is sealed with the dynamic sealing film at the top end, so that a sealed space is formed between the workbench, the cabin body and the dynamic sealing film; The dynamic sealing film is dynamically sealed with the transmission rod; The air inlet pipe penetrates through the side wall of the cylinder, one end of which is connected with the hydrogen supply system and the water supply system, and the other end of which is located at the bottom of the cabin body and is provided with a plurality of small holes, which are used to deliver hydrogen and water or water vapor into the oil; The heating device is fixedly installed on the cylinder, which is used to heat the oil; The temperature sensor is used to detect the oil temperature in real time; The humidity sensor is used to detect the humidity in the cabin body in real time; The hydrogen sensor is used to monitor the hydrogen concentration in the cabin body in real time; The central control system is signal connected with the heating device, the temperature sensor, the humidity sensor and the hydrogen sensor, which is used to control the heating device.

4. The method for evaluating lubricating properties of engine oil for hydrogen internal combustion engine according to claim 3, characterized by, The hydrogen supply system comprises a hydrogen cylinder or a hydrogen production device, a pressure reducing valve, a stop valve, a check valve, a pressure gauge and a mass flow controller; The outlet of the hydrogen cylinder or the hydrogen production device is connected to the inlet pipe through a pipeline, and the pressure reducing valve, the shut-off valve, the check valve, the pressure gauge and the mass flow controller are installed in sequence in the pipeline. The mass flow controller is used to control the mass flow rate of hydrogen. The central control system regulates the hydrogen concentration by controlling the shut-off valve and the mass flow controller.

5. The method for evaluating lubricating properties of engine oil for hydrogen internal combustion engine according to claim 4, characterized by, The cabin is also equipped with an exhaust port that can be opened and closed, and an exhaust pipe connected to the exhaust port. The exhaust pipe is equipped with a filter, and the other end of the exhaust pipe extends outdoors.

6. The method for evaluating lubricating properties of engine oil for hydrogen internal combustion engine according to claim 5, characterized by, The controllable hydrogen internal combustion engine simulation environment test platform also includes a security system to maintain the safety of the test environment; The security system includes an exhaust hood, an audible and visual alarm, a gas sensor, and an explosion-proof fan; The exhaust hood is installed on top of the friction and wear testing machine; The audible and visual alarm, the gas sensor, and the explosion-proof fan are all connected to the central control system.

7. The method for evaluating lubricating properties of engine oil for hydrogen internal combustion engine according to claim 3, characterized by, The gas environment chamber also includes a pressure sensor installed inside the chamber, which is used to monitor the gas pressure inside the chamber in real time and is connected to the central control system.

8. The method for evaluating lubricating properties of engine oil for hydrogen internal combustion engine according to claim 3, characterized by, The lubrication system includes an oil pump, an oil inlet pipe, and an oil outlet pipe; Both the oil inlet pipe and the oil outlet pipe are installed through the side wall of the cylinder body. Both the oil inlet pipe and the oil outlet pipe are connected to the oil pump and are used to spray engine oil to the top of the cylinder liner through the oil pump.

9. The method for evaluating lubricating properties of engine oil for hydrogen internal combustion engine according to any one of claims 2 to 8, characterized in that, The central control system adopts a PLC measurement and control system.

Images