An engine cylinder head lubricating oil return simulation evaluation method and system

Abstract

The application discloses an engine cylinder cover lubricating oil return simulation evaluation method and system, comprising: constructing an engine cylinder cover lubricating oil simulation model, the simulation model comprising components contacted by lubricating oil in the lubricating oil return process of the engine cylinder cover and components of a crankcase ventilation system; setting initial conditions of the simulation model, including initial lubricating oil quantity and corresponding liquid level coordinate values; setting boundary conditions, simulating for set working conditions, performing cylinder cover return simulation in a first stage, and obtaining static oil storage quantity in the cylinder cover in a second stage; recording simulation results, evaluating cylinder cover lubricating oil return conditions by using the simulation results, and judging whether the cylinder cover lubricating oil return is smooth or not. The cylinder cover lubricating oil return simulation method can estimate the lubricating return effect of the engine cylinder cover at the initial design stage, has fewer condition restrictions, is lower in cost than tests, and is higher in efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of engine lubrication system, and in particular to an engine cylinder head lubricating oil return simulation evaluation method and system. BACKGROUND

[0002] The statements in this section merely provide background information related to the present application and do not necessarily constitute the prior art.

[0003] The engine lubrication system provides lubricating oil for bearings, hydraulic mechanisms and other oil components. The lubricating oil is supplied from the oil pan to the cylinder head oil passage, and then enters the camshaft bearing, hydraulic tappet, high-pressure oil pump tappet mechanism, etc. The lubricating oil is injected into the cylinder head from the bearing gap and the rocker arm hole connected to the hydraulic tappet, and flows in the cylinder head, and then flows downward from the oil return hole back to the oil pan.

[0004] Under normal circumstances, the engine oil in the cylinder head should flow smoothly back to the oil pan to avoid poor lubricating oil return, excessive accumulation in the cylinder head oil chamber, and oil blow-by from the ventilation hole of the crankcase ventilation system, resulting in oil blow-by. At the same time, the oil pump cannot pump oil from the oil pan to the lubricating parts in time, causing shaft diameter damage, etc., and causing unnecessary negative effects on the engine.

[0005] Currently, the cylinder head oil return condition is mainly tested by experimental methods to determine whether there is oil blow-by. The test stage is in the late stage of engine and engine component development, and requires a finished product assembled engine. If problems are found, the time cost and cost of changing the engine design are relatively large. SUMMARY

[0006] To solve the above problems, the present application provides an engine cylinder head lubricating oil return simulation evaluation method and system, which can estimate the engine cylinder head lubricating return effect at the design stage by simulation method, and has lower cost and higher efficiency compared with experimental method.

[0007] In some embodiments, the following technical solutions are adopted:

[0008] An engine cylinder head lubricating oil return simulation evaluation method, comprising:

[0009] An engine cylinder head lubricating oil simulation model is constructed, which includes components that the lubricating oil will contact during the engine cylinder head lubricating oil return process, and components of the crankcase ventilation system;

[0010] The initial conditions of the simulation model are set, including the initial lubricating oil amount and the corresponding liquid surface coordinate value;

[0011] The boundary conditions are set, and the simulation is simulated for the set working condition. The first stage is cylinder head return simulation, and the second stage is to obtain the static oil storage amount in the cylinder head.

[0012] Record the simulation results and use them to evaluate the cylinder head oil return to determine whether the cylinder head oil return is smooth.

[0013] As a further solution, the lubricating oil outlet boundary of the simulation model maintains the original geometric shape as much as possible; an oil outlet structure is added to the oil pan, and an L-shaped pipe structure is added to the oil outlet. The outlet of the L-shaped pipe structure is level with the initial lubricating oil liquid level to maintain the total amount of lubricating oil within the set range.

[0014] As a further solution, a circular cup structure is added to the labyrinth oil return hole of the simulation model to cover the oil return hole. After the circular cup is filled with lubricating oil, the labyrinth oil return hole will be completely immersed below the liquid level of the circular cup, realizing one-way flow of lubricating oil.

[0015] As a further solution, the engine cylinder head lubricating oil return test conditions have different inclination angles. Each condition uses the same coordinate system and gravity acceleration direction. The simulation model is rotated by the corresponding angle according to the requirements of the test condition to achieve a state consistent with the test condition.

[0016] As a further solution, the engine cylinder head lubricating oil return simulation model adopts an Euler multiphase model, which includes two phases, gas and lubricating oil, and satisfies the physical simulation of continuous coexistence of gas and liquid.

[0017] As a further solution, the boundary conditions are specifically set as follows:

[0018] The lubricant loading boundary is the mass flow inlet, and the lubricant flow rate at each location is obtained through a one-dimensional lubrication system or loaded with a reference value;

[0019] The piston leakage loading boundary is the mass flow inlet. The specific value is obtained through the piston leakage test or by inputting a reference value.

[0020] The lubricating oil and piston leakage temperature settings are based on the test conditions; the outlet of the labyrinth vent is set as the pressure boundary, and the pressure value under the corresponding working condition is obtained through the crankcase test, or a reference value is input;

[0021] The L-shaped pipe outlet on the oil pan is set as a pressure outlet, and the pressure level refers to the crankcase pressure level.

[0022] As a further solution, the recording of simulation results specifically includes:

[0023] The simulation results include the flow rate of each oil return hole in the cylinder head, the ventilation of each oil return hole in the cylinder head, the air flow rate and lubricating oil flow rate of the three crankcase ventilation holes and the oil outlet of the oil pan of the valve cover maze, the difference between the total amount of lubricating oil added and the oil return amount of each cylinder head, the difference between the injection rate of lubricating oil and the return rate of each return hole, the total amount of lubricating oil, the amount of lubricating oil in the upper area and the amount of lubricating oil in the lower area; and reports of corresponding simulation results are generated respectively.

[0024] As a further solution, the simulation results were used to evaluate the cylinder head oil return condition to determine whether the cylinder head oil return is smooth. Specifically:

[0025] If the difference curve between the predefined injection oil rate and the return rate of each return hole eventually approaches zero, there will be no continuous oil accumulation in the cylinder head, indicating that the cylinder head lubricating oil is returning smoothly;

[0026] If the difference curve of the pre-defined injection lubricating oil rate minus the reflux rate of each reflux hole does not ultimately approach zero or the difference from zero exceeds the set value, the liquid level in the cylinder head continues to rise, and a large amount of lubricating oil overflows from the cylinder head ventilation holes, it means that the lubricating oil reflux is not smooth and oil leakage occurs.

[0027] As a further solution, the method also includes: optimizing the design of the engine cylinder head using the simulation results; specifically:

[0028] Through the results of lubricating oil flow in the cylinder head, confirm whether the lubricating oil in various parts of the cylinder head can flow smoothly to the oil return hole. If not, optimize the location of blockage and flow problems based on the results;

[0029] Based on the ventilation and flow results of each oil return hole, compare the ventilation ratio and oil return ratio of each hole to optimize the position and size of the oil return hole;

[0030] Based on the air output results of the crankcase vents, compare the air output ratio and optimize the position and size of the air outlet;

[0031] Based on the oil storage results, the oil storage results in the working and static cylinder heads, and the oil storage level position results, the position of the Qutong maze air inlet is optimized.

[0032] In other embodiments, the following technical solutions are adopted:

[0033] An engine cylinder head lubricating oil return simulation evaluation system, comprising:

[0034] a model building module for building a simulation model of the engine cylinder head lubricating oil, the simulation model including components that the lubricating oil will contact during the oil return process of the engine cylinder head and components of the crankcase ventilation system;

[0035] The parameter setting module is used to set the initial conditions of the simulation model, including the initial lubricating oil volume and the corresponding liquid level coordinate value;

[0036] The simulation module is used to set boundary conditions and simulate the set working conditions. The first stage simulates the oil return from the cylinder head, and the second stage obtains the static oil storage volume in the cylinder head.

[0037] The evaluation module is used to record the simulation results, use the simulation results to evaluate the cylinder head lubricating oil return situation, and determine whether the cylinder head lubricating oil return is smooth.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] (1) The cylinder head lubricant return simulation method of the present invention can estimate the lubrication return effect of the engine cylinder head at the early stage of design. It has fewer restrictions, is less costly than experimental testing, and is more efficient. The cylinder head lubricant return simulation analysis and optimization are achieved at the early stage of design, avoiding the time and cost of later modifications.

[0040] (2) The simulation method of the present invention includes models of the valve cover labyrinth ventilation system, camshaft, and oil return channel, and the model is highly complete. The oil filling boundary and gas inlet and outlet boundaries use the original geometry as much as possible, and the oil volume maintenance and labyrinth oil return one-way circulation design are added. Ultimately, it can accurately estimate the lubricating oil return effect, gas circulation status, cylinder head oil storage volume and other results.

[0041] Other features and advantages of additional aspects of the present invention will be given in part in the following description and in part will become obvious from the following description or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 Schematic diagram of the intake side of the lubricating oil return simulation model of the engine cylinder head according to an embodiment of the present invention;

[0043] Figure 2 This is a schematic diagram of the exhaust side of a simulation model according to an embodiment of the present invention;

[0044] Figure 3 Schematic diagram of the interface between the upper and lower calculation domains of the simulation model according to an embodiment of the present invention;

[0045] Figure 4 This is a schematic diagram of the interior of a cylinder head of a simulation model according to an embodiment of the present invention;

[0046] Figure 5 This is a schematic diagram of the oil outlet structure of the oil pan of the simulation model according to an embodiment of the present invention;

[0047] Figure 6 Schematic diagram of simulation analysis results of an embodiment of the present invention. DETAILED DESCRIPTION

[0048] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0049] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0050] Example 1

[0051] In one or more embodiments, a method for simulating and evaluating lubricating oil return from an engine cylinder head is disclosed, specifically comprising the following steps:

[0052] (1) constructing an engine cylinder head lubricating oil simulation model, wherein the simulation model includes components that the lubricating oil will contact during the oil return process of the engine cylinder head and components of the crankcase ventilation system;

[0053] Specifically, the embodiment of the present invention simulates the return of lubricating oil from the cylinder head of a certain engine. By calculation, relatively accurate results such as the cylinder head oil storage amount, the return oil hole lubricating oil flow and ventilation flow, and the tortuous gas flow can be obtained. Based on the results, it can be more intuitively determined whether the oil return is smooth and whether there is oil blowby.

[0054] like Figure 1 、 Figure 2 、 Figure 3 As shown in the figure, the engine cylinder head lubricating oil simulation model is relatively detailed and complete, including the main components: valve cover inner wall surface ①, tortuous outlet 1 ②, tortuous outlet 2 ③, cylinder head inner wall surface ④, timing cover inner wall surface ⑤, cylinder block and cylinder liner inner wall surface ⑥, oil pan inner wall surface ⑦, valve cover tortuous maze ⑧, tortuous outlet 3 ⑨, engine oil cooler ⑩, oil pan oil outlet Upper and lower computational domain interface camshaft and rocker arm wait.

[0055] like Figure 4 As mentioned above, the simulation model adds an interface below the cylinder head, dividing the entire simulation model into two upper and lower calculation domains. The upper calculation domain can be used to conveniently calculate the oil storage volume in the cylinder head;

[0056] In this embodiment, the inlet and outlet boundaries of the lubricating oil and piston leakage are maintained as much as possible in their original geometry. The tappet outlet hole is a circular hole on the rocker arm, the bearing oil outlet is a torus, and the piston leakage loading boundary is processed into a torus.

[0057] like Figure 5 As described above, an L-shaped pipe structure is added to the oil drain port of the oil pan, and the outlet of the L-shaped pipe is level with the initial lubricating oil level. When the engine oil returning from the cylinder head flows into the oil pan, the liquid level increases, and the lubricating oil will flow out from the oil outlet, thereby maintaining the liquid level at a set height.

[0058] The labyrinth oil return hole cover is increased with a round cup structure to cover the outlet hole. When the round cup is filled with lubricating oil, the labyrinth oil return hole will be completely immersed below the liquid level of the round cup, thus realizing one-way flow of lubricating oil.

[0059] The engine cylinder head lubricating oil return test conditions may have different inclination angles. Each condition uses the same coordinate system and gravity acceleration direction. The simulation model can be rotated by the corresponding angle according to the requirements of the test condition to achieve a state consistent with the test condition.

[0060] After the simulation model is processed, the physical model for the cylinder head oil return simulation uses an Euler multiphase model, consisting of two phases: gas and oil. The single-phase ratio ranges from 0 to 1. When the air phase ratio in the simulation domain is 0, it indicates that it is entirely oil. Conversely, when the air phase ratio is 1, it indicates that it is entirely air.

[0061] The simulation physical model selected the fluid domain volume model, which can realize the mutual influence and coexistence of gas and oil in the same simulation model.

[0062] (2) Setting the initial conditions of the simulation model, including the initial lubricating oil volume and the corresponding liquid level coordinate values;

[0063] In this embodiment, the simulation takes into account the influence of temperature, as well as the temperature of the gas and the pressure level of the crankcase ventilation system, and inputs parameters such as the density, viscosity, and specific heat of the gas and lubricating oil under corresponding conditions into the physical model.

[0064] To fit the actual situation, the simulation process takes into account the influence of gravity, specifies the magnitude and direction of gravitational acceleration, and sets the direction of gravity to the -Z direction of the simulation software.

[0065] To set the initial lubricant level, you need to know the lubricant amount and the corresponding Z-axis liquid level coordinate Z0 in advance. During simulation, a function is used to define the initial lubricant content below Z0. This means that when the Z coordinate of the simulation area is less than or equal to the liquid level Z0, the lubricant content is 1, meaning that the area below Z0 is entirely lubricant and the area above Z0 is air.

[0066] (3) Setting boundary conditions and performing simulation for the set working conditions, the first stage is the cylinder head oil return simulation, and the second stage is the static oil storage volume in the cylinder head;

[0067] In this embodiment, the simulation simulates the instantaneous unsteady flow, the simulation flow domain changes continuously with time, the total calculation time is 2 minutes, the time step is 0.002 seconds, and the inner iteration step is 10.

[0068] The mass flow inlet is selected as the lubricating oil loading boundary. The lubricating oil flow rate at each location is obtained through a one-dimensional lubrication system, or a reference value is loaded. The mass flow inlet is selected as the piston leakage loading boundary. The specific value can be obtained through a piston leakage test, or a reference value can be entered. The lubricating oil and piston leakage temperature settings are based on the test conditions. The outlet of the labyrinth vent is set as the pressure boundary. The pressure value under the corresponding operating conditions can be obtained through a crankcase test, or a reference value can be entered. The L-shaped pipe outlet on the oil pan is set as a pressure outlet, and the pressure level is referenced to the crankcase pressure level.

[0069] The simulation is divided into two phases. The first phase simulates the cylinder head oil return flow, while the second phase primarily aims to determine the static oil volume within the cylinder head. Once the cylinder head oil return flow calculation reaches the stopping criteria, the flow rates at each lubricant and piston blowby boundary are set to zero, and the outlet pressure is set to zero. The calculation is then extended and continued until the cylinder head oil return flow reaches zero and the lubricant volume within the upper flow domain stabilizes. The calculation is then terminated.

[0070] Figure 6 A schematic diagram of the simulation analysis results is given. Through the simulation results, the situation and speed of the lubricating oil backflow at various positions in the cylinder head cavity can be intuitively seen, thereby judging whether the position of the cylinder head oil return hole is appropriate.

[0071] (4) Record the simulation results and use them to evaluate the cylinder head lubricating oil return situation to determine whether the cylinder head lubricating oil return is smooth.

[0072] In this example, to monitor process status, you need to create reports in advance, along with corresponding real-time monitoring records and charts. For the flow rate report for each oil return port in the cylinder head, select Euler multiphase mass flow report for the report type, select lubricant for the phase attribute, and select the interfaces at the upper and lower computational domain layers for the components. Create real-time monitoring and generate charts.

[0073] For ventilation reports on the oil return holes in the cylinder head, select Euler multiphase mass flow report as the report type, select air as the phase attribute, select the interfaces at the upper and lower calculation domain layers as the components, create real-time monitoring records, and generate charts.

[0074] Use the same method as above to create reports, monitoring records and charts of the air flow and lubricating oil flow of the three crankcase ventilation holes and the oil pan outlet of the valve cover maze.

[0075] The difference between the total amount of lubricating oil added and the oil return amount of each cylinder head is created into an expression report with the unit of kg / s. The expression definition is: oil injection amount - mass flow rate of each oil return hole. Real-time monitoring records are created and charts are generated.

[0076] The total amount of lubricating oil, the upper flow lubricating oil amount and the lower area lubricating oil amount, the report type is volume integral, the field function selects the lubricating oil volume fraction, and the parts select the upper calculation domain, the lower calculation domain and the overall calculation respectively, create a real-time monitoring record and generate a chart.

[0077] To monitor the process status, you need to create scenarios with interesting results in advance and set them to automatically save images. This will primarily observe the lubricant's state at corresponding proportions at different times. Create a scenario for the lubricant mass fraction, select Scalar for the scenario type, All Fluid Domains for the scenario components, and Lubricant Volume Analysis for the field function. Check the Update Activation checkbox and select Image Storage, setting the storage interval to 0.1s. The stored result images will be used later to create animated graphics, providing a visual demonstration of the entire oil return process from start to finish.

[0078] After the calculation is completed, the cylinder head lubricating oil return is evaluated through simulation results:

[0079] Specifically, check the difference between the predefined lubricant injection rate and the return rate of each return hole. If this difference curve eventually approaches zero, there will be no persistent oil accumulation in the cylinder head, and the lubricant outflow from the curved maze outlet holes is zero or minimal, indicating smooth cylinder head lubricant return. If the difference between the lubricant injection rate and the return rate does not approach zero, and the liquid level in the cylinder head continues to rise, with a large amount of lubricant overflowing from the cylinder head vent holes, it indicates that the lubricant return is not smooth and oil crossover is occurring.

[0080] As an optional method, it also includes: optimizing the design of the engine cylinder head using the simulation results;

[0081] Specifically:

[0082] Through the results of lubricating oil flow in the cylinder head, confirm whether the lubricating oil in various parts of the cylinder head can flow smoothly to the oil return hole. If not, optimize the location of blockage and flow problems based on the results;

[0083] Based on the ventilation and flow results of each oil return hole, compare the ventilation ratio and oil return ratio of each hole to optimize the position and size of the oil return hole;

[0084] Based on the air output results of the crankcase vents, compare the air output ratio and optimize the position and size of the air outlet;

[0085] Based on the oil storage results, the oil storage results in the working and static cylinder heads, and the oil storage level position results, the position of the Qutong maze air inlet is optimized.

[0086] Example 2

[0087] In one or more embodiments, a system for simulating and evaluating lubricating oil return from an engine cylinder head is disclosed, comprising:

[0088] a model building module for building a simulation model of the engine cylinder head lubricating oil, the simulation model including components that the lubricating oil will contact during the oil return process of the engine cylinder head and components of the crankcase ventilation system;

[0089] The parameter setting module is used to set the initial conditions of the simulation model, including the initial lubricating oil volume and the corresponding liquid level coordinate value;

[0090] The simulation module is used to set boundary conditions and simulate the set working conditions. The first stage simulates the oil return from the cylinder head, and the second stage obtains the static oil storage volume in the cylinder head.

[0091] The evaluation module is used to record the simulation results, use the simulation results to evaluate the cylinder head lubricating oil return situation, and determine whether the cylinder head lubricating oil return is smooth.

[0092] It should be noted that the specific implementation of the above modules has been described in Example 1 and will not be described in detail here.

[0093] Although the above describes the specific embodiments of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without any creative work are still within the scope of protection of the present invention.

Claims

1. A simulation evaluation method for lubricating oil return of an engine cylinder head, characterized in that: include: Constructing an engine cylinder head lubricating oil simulation model, the simulation model including components that the lubricating oil will contact during the lubricating oil return process of the engine cylinder head and components of the crankcase ventilation system; Set the initial conditions of the simulation model, including the initial lubricating oil volume and the corresponding liquid level coordinate value; Set boundary conditions and perform simulation for the set working conditions. The first stage is to simulate the cylinder head oil return, and the second stage is to obtain the static oil storage volume in the cylinder head. The set boundary conditions are specifically as follows: The lubricant loading boundary is the mass flow inlet, and the lubricant flow rate at each location is obtained through a one-dimensional lubrication system or loaded with a reference value; The piston leakage loading boundary is the mass flow inlet. The specific value is obtained through the piston leakage test or by inputting a reference value. The lubricating oil and piston leakage temperature settings are based on the test conditions; the outlet of the labyrinth vent is set as the pressure boundary, and the pressure value under the corresponding working condition is obtained through the crankcase test, or a reference value is input; The L-shaped pipe outlet on the oil pan is set as a pressure outlet, and the pressure level refers to the crankcase pressure level; The simulation results are recorded and used to evaluate the cylinder head lubricating oil return condition to determine whether the cylinder head lubricating oil return is smooth; the simulation results include the flow rate of each oil return hole of the cylinder head, the ventilation of each oil return hole of the cylinder head, the air flow rate and lubricating oil flow rate of the three crankcase ventilation holes of the valve cover maze and the oil pan oil outlet, the difference between the total amount of lubricating oil added and the oil return amount of each cylinder head, the difference between the lubricating oil injection rate and the reflux rate of each return hole, the total amount of lubricating oil, the lubricating oil amount in the upper area and the lubricating oil amount in the lower area; and reports of the corresponding simulation results are generated respectively.

2. The engine cylinder head lubricating oil return simulation evaluation method according to claim 1, characterized in that: The lubricating oil outlet boundary of the simulation model maintains the original geometric shape as much as possible; an oil outlet structure is added to the oil pan, and an L-shaped pipe structure is added to the oil outlet. The outlet of the L-shaped pipe structure is level with the initial lubricating oil liquid level to maintain the total amount of lubricating oil within the set range.

3. The engine cylinder head lubricating oil return simulation evaluation method according to claim 1, characterized in that: The labyrinth oil return hole of the simulation model is covered with a circular cup structure to cover the oil return hole. After the circular cup is filled with lubricating oil, the labyrinth oil return hole will be completely immersed below the liquid level of the circular cup, realizing one-way flow of lubricating oil.

4. The engine cylinder head lubricating oil return simulation evaluation method according to claim 1, characterized in that: The engine cylinder head lubricating oil return test conditions have different inclination angles. Each condition uses the same coordinate system and gravity acceleration direction. By rotating the simulation model at the corresponding angle according to the requirements of the test condition, the simulation model can be made consistent with the test condition.

5. The engine cylinder head lubricating oil return simulation evaluation method according to claim 1, characterized in that: The engine cylinder head lubricating oil return simulation model adopts the Euler multiphase model, which includes two phases, gas and lubricating oil, and satisfies the physical simulation of the continuous coexistence of gas and liquid.

6. The engine cylinder head lubricating oil return simulation evaluation method according to claim 1, characterized in that: The simulation results are used to evaluate the cylinder head oil return condition and determine whether the cylinder head oil return is smooth. Specifically: If the difference curve between the predefined injection oil rate and the return rate of each return hole eventually approaches zero, there will be no continuous oil accumulation in the cylinder head, indicating that the cylinder head lubricating oil is returning smoothly; If the difference curve of the pre-defined injection lubricating oil rate minus the reflux rate of each reflux hole does not ultimately approach zero or the difference from zero exceeds the set value, the liquid level in the cylinder head continues to rise, and a large amount of lubricating oil overflows from the cylinder head ventilation holes, it means that the lubricating oil reflux is not smooth and oil leakage occurs.

7. The engine cylinder head lubricating oil return simulation evaluation method according to claim 1, characterized in that: It also includes: using simulation results to optimize the design of the engine cylinder head; specifically: Through the results of lubricating oil flow in the cylinder head, confirm whether the lubricating oil in various parts of the cylinder head can flow smoothly to the oil return hole. If not, optimize the location of blockage and flow problems based on the results; Based on the ventilation and flow results of each oil return hole, compare the ventilation ratio and oil return ratio of each hole to optimize the position and size of the oil return hole; Based on the air output results of the crankcase vents, compare the air output ratio and optimize the position and size of the air outlet; Based on the oil storage results, the oil storage results in the working and static cylinder heads, and the oil storage level position results, the position of the Qutong maze air inlet is optimized.

8. An engine cylinder head lubricating oil return simulation evaluation system, characterized in that: include: a model building module for building a simulation model of the engine cylinder head lubricating oil, the simulation model including components that the lubricating oil will contact during the oil return process of the engine cylinder head and components of the crankcase ventilation system; The parameter setting module is used to set the initial conditions of the simulation model, including the initial lubricating oil volume and the corresponding liquid level coordinate value; The simulation module is used to set boundary conditions and simulate the set working conditions. The first stage is to simulate the oil return of the cylinder head, and the second stage is to obtain the static oil storage volume in the cylinder head. The set boundary conditions are specifically: The lubricant loading boundary is the mass flow inlet, and the lubricant flow rate at each location is obtained through a one-dimensional lubrication system or loaded with a reference value; The piston leakage loading boundary is the mass flow inlet. The specific value is obtained through the piston leakage test or by inputting a reference value. The lubricating oil and piston leakage temperature settings are based on the test conditions; the outlet of the labyrinth vent is set as the pressure boundary, and the pressure value under the corresponding working condition is obtained through the crankcase test, or a reference value is input; The L-shaped pipe outlet on the oil pan is set as a pressure outlet, and the pressure level refers to the crankcase pressure level; An evaluation module is used to record simulation results, use the simulation results to evaluate the cylinder head lubricating oil return situation, and determine whether the cylinder head lubricating oil return is smooth; the simulation results include the flow rate of each oil return hole in the cylinder head, the ventilation of each oil return hole in the cylinder head, the air flow rate and lubricating oil flow rate of the three crankcase ventilation holes and the oil pan oil outlet of the valve cover maze, the difference between the total amount of lubricating oil added and the oil return amount of each cylinder head, the difference between the lubricating oil injection rate and the reflux rate of each return hole, the total amount of lubricating oil, the lubricating oil amount in the upper area, and the lubricating oil amount in the lower area; and generate reports of corresponding simulation results respectively.

9. The engine cylinder head lubricating oil return simulation evaluation system according to claim 8, characterized in that: The lubricating oil outlet boundary of the simulation model maintains the original geometric shape as much as possible; an oil outlet structure is added to the oil pan, and an L-shaped pipe structure is added to the oil outlet. The outlet of the L-shaped pipe structure is level with the initial lubricating oil liquid level to maintain the total amount of lubricating oil within the set range.

10. The engine cylinder head lubricating oil return simulation evaluation system according to claim 8, characterized in that: The labyrinth oil return hole of the simulation model is covered with a circular cup structure to cover the oil return hole. After the circular cup is filled with lubricating oil, the labyrinth oil return hole will be completely immersed below the liquid level of the circular cup, realizing one-way flow of lubricating oil.

11. The engine cylinder head lubricating oil return simulation evaluation system according to claim 8, characterized in that: The engine cylinder head lubricating oil return test conditions have different inclination angles. Each condition uses the same coordinate system and gravity acceleration direction. By rotating the simulation model at the corresponding angle according to the requirements of the test condition, the simulation model can be made consistent with the test condition.

12. The engine cylinder head lubricating oil return simulation evaluation system according to claim 8, characterized in that: The engine cylinder head lubricating oil return simulation model adopts the Euler multiphase model, which includes two phases, gas and lubricating oil, and satisfies the physical simulation of the continuous coexistence of gas and liquid.

13. The engine cylinder head lubricating oil return simulation evaluation system according to claim 8, characterized in that: The simulation results are used to evaluate the cylinder head oil return condition and determine whether the cylinder head oil return is smooth. Specifically: If the difference curve between the predefined injection oil rate and the return rate of each return hole eventually approaches zero, there will be no continuous oil accumulation in the cylinder head, indicating that the cylinder head lubricating oil is returning smoothly; If the difference curve of the pre-defined injection lubricating oil rate minus the reflux rate of each reflux hole does not ultimately approach zero or the difference from zero exceeds the set value, the liquid level in the cylinder head continues to rise, and a large amount of lubricating oil overflows from the cylinder head ventilation holes, it means that the lubricating oil reflux is not smooth and oil leakage occurs.

14. The engine cylinder head lubricating oil return simulation evaluation system according to claim 8, characterized in that: It also includes: using simulation results to optimize the design of the engine cylinder head; specifically: Through the results of lubricating oil flow in the cylinder head, confirm whether the lubricating oil in various parts of the cylinder head can flow smoothly to the oil return hole. If not, optimize the location of blockage and flow problems based on the results; Based on the ventilation and flow results of each oil return hole, compare the ventilation ratio and oil return ratio of each hole to optimize the position and size of the oil return hole; Based on the air output results of the crankcase vents, compare the air output ratio and optimize the position and size of the air outlet; Based on the oil storage results, the oil storage results in the working and static cylinder heads, and the oil storage level position results, the position of the Qutong maze air inlet is optimized.

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