Threshold screening and cold-heat shock closed-loop optimization method for cylinder head cover double-beam gasket

Abstract

The application discloses a cylinder cover double-beam sealing gasket threshold screening and cold-heat impact closed-loop optimization method, and belongs to the field of automobile engine sealing structure design. The method comprises the following steps: obtaining initial cross-section structure parameters and assembly condition parameters of a cylinder cover double-beam sealing gasket, and establishing a sealing parameter system; constructing a double-beam sealing gasket structure parameter model and establishing a parameter mapping relationship; based on finite element analysis assembly condition simulation, adopting multi-parameter joint threshold screening candidate structure; performing cold-heat impact test verification on the candidate structure in accordance with the GMW3155 standard; correcting structure parameters by comparing test and simulation results; and storing the verified parameters into a product database to form a backstepping rule. Through the closed-loop optimization process of "simulation-test-correction-backstepping", the application realizes efficient and accurate design of double-beam sealing gasket structure parameters, solves the problem that traditional design relies on experience and simulation and test are disconnected, and improves the reliability and design efficiency of long-term sealing performance of the sealing gasket.

Description

Technical Field

[0001] This invention relates to the field of automotive engine sealing structure design technology, and in particular to a method for multi-parameter threshold screening and thermal shock closed-loop optimization of a cylinder head cover double-ribbed sealing gasket. Background Technology

[0002] As a crucial sealing component of the engine, the cylinder head cover's sealing performance directly impacts the engine's reliability, safety, and service life. Cylinder head cover gaskets are typically made of rubber or rubber composites, and in the assembled state, they generate a certain contact pressure to prevent leakage of lubricating oil, fuel gas, and other media. However, due to the complex operating conditions of engines—high temperature, high pressure, and frequent thermal cycles—the gaskets are prone to permanent compression deformation, creep, and contact pressure attenuation, leading to seal failure. Therefore, the rational design and optimization of the cylinder head cover gasket structure is a vital technical aspect for improving the overall reliability of the engine.

[0003] Currently, the structural design of cylinder head cover gaskets typically relies on engineering experience combined with finite element analysis and experimental verification. The common process involves selecting the gasket's cross-sectional shape and dimensional parameters based on experience, evaluating contact pressure and deformation through finite element analysis, and then verifying the design through bench tests or thermal shock tests. However, this approach still has significant shortcomings in practical applications: firstly, there is often a certain deviation between finite element analysis results and actual experimental results, lacking an effective parameter correction and feedback mechanism; secondly, there is a lack of clear quantitative mapping relationships between key sealing parameters (such as fill rate, compression ratio, creep, etc.) and gasket structural parameters, leading to repetitive trial and error and low efficiency in the structural optimization process, making it difficult to meet the dual requirements of modern engines for sealing performance and development cycle.

[0004] To address this, this invention proposes a multi-parameter threshold screening and thermal shock closed-loop optimization method for cylinder head cover double-rib gaskets. By establishing a key sealing parameter system for the cylinder head cover gasket, a structural parameter model of the double-rib gasket is constructed. Based on finite element analysis, the contact stress distribution and deformation behavior of the gasket under assembly conditions are simulated and evaluated. Furthermore, thermal shock tests conforming to GMW3155 standards are introduced to verify and check candidate structures. By comparing and analyzing the finite element analysis results with the thermal shock test results, the structural parameters of the double-rib gasket are specifically corrected. The corrected structural parameters and corresponding performance evaluation results are stored in a product database, forming parameter back-calculation and optimization decision rules for subsequent gasket structure design. This method organically combines finite element analysis, standardized thermal shock tests, and a key sealing parameter system, constructing a closed-loop optimization process of structural parameters—performance indicators—test verification. This effectively solves the problems of reliance on experience in gasket structure design, disconnect between simulation and testing, and low optimization efficiency in existing technologies, significantly improving the reliability and engineering efficiency of cylinder head cover gasket structure design.

[0005] Regarding methods for optimizing the cylinder head cover gasket structure, the following comparative patents and literature exist: "A Cylinder Head Cover Gasket Sealing Detection Method Based on Finite Element Analysis," patent number CN107491570 B. This invention discloses a method for determining whether the sealing structure meets sealing requirements by establishing finite element models of components such as the cylinder head cover, gasket, and bolts, and analyzing the contact pressure distribution of the gasket under different operating conditions. While this method can detect and evaluate the sealing performance of the cylinder head cover gasket through finite element analysis, it primarily focuses on the analysis and determination of the sealing state, without further integrating the finite element analysis results with experimental verification results to form a systematic optimization closed loop for structural parameters.

[0006] "A Design Method for Engine Cylinder Head Gaskets," patent number CN112733294 A. This invention proposes a method that incorporates the temperature field corresponding to different reliability bench tests into a finite element analysis model. By calculating and evaluating parameters such as sealing pressure and dynamic separation clearance, it determines whether the cylinder head gasket structure meets design requirements. This method considers the impact of hot and cold operating conditions on sealing performance to some extent; however, its research focuses primarily on the engine cylinder head gasket structure and emphasizes performance evaluation under multiple operating conditions. It does not establish a quantitative mapping relationship between key sealing parameters and structural parameters for the specific structural form of the cylinder head gasket, nor does it incorporate standardized thermal shock test results for reverse correction of structural parameters.

[0007] A paper titled "Design of Rubber Seals for Disc Brakes Based on Finite Element Method," published in 2015 by Tan et al. from the School of Mechanical Engineering at a university in Jiangsu Province, proposed using the nonlinear finite element method to analyze the stress and deformation behavior of rubber seals under different interference fits and temperature conditions, and explored the influence of interference fit and temperature on sealing performance. This research provides a useful reference for the structural design of rubber seals; however, its research object is mainly rubber seals for braking systems, focusing on the comparison and verification of finite element analysis results, and has not yet established a structural optimization method system for engineering applications by incorporating standardized thermal shock tests. Summary of the Invention

[0008] To address the aforementioned technical problems, the present invention aims to provide a threshold screening and thermal shock closed-loop optimization method for cylinder head cover double-rib gaskets. By establishing a quantitative mapping between structural parameters and sealing performance, and through closed-loop verification and correction of finite element analysis and standardized tests, this method solves the problems of traditional design relying on experience, disconnect between simulation and testing, and low optimization efficiency, thereby improving the reliability and engineering efficiency of cylinder head cover gasket structural design.

[0009] The objective of this invention is achieved through the following technical solution: The threshold screening and thermal shock closed-loop optimization method for cylinder head cover double-ribbed gaskets includes the following steps: Step 10. Obtain the initial cross-sectional structural parameters and assembly condition parameters of the cylinder head cover double-rib gasket, and establish a sealing parameter system; Step 20. Construct a structural parameter model of the double-ribbed sealing gasket and establish the mapping relationship between the structural parameters and the sealing parameters; Step 30. Establish a finite element analysis model including the gasket, cylinder head cover and mounting surface based on the structural parameter model of the double-ribbed gasket; Step 40. Extract the finite element analysis results and compare them with the preset multi-parameter joint performance threshold range; Step 50. Perform thermal shock tests on the selected candidate double-ribbed sealing gasket structures to verify their validity; Step 60. Calculate the performance deviation between the finite element prediction results and the experimental results; Step 70. Store the structural parameters, corresponding sealing parameters, and performance evaluation results verified by the thermal shock test into the product database; Step 80. Based on the finite element analysis results verified by thermal shock tests, the structural parameters of the double-ribbed gasket are finally optimized and adjusted to determine the target structural parameter combination that meets the sealing performance requirements, and the optimized results of the cylinder head cover gasket structure are output.

[0010] Furthermore, step 10 includes: The cross-sectional structural parameters of the cylinder head cover gasket include the cross-sectional area of ​​the gasket. Effective cross-sectional area of ​​the sealing groove Free height of sealing gasket The cylinder head cover sealing gasket assembly parameters include the height after assembly compression. ; Based on the cross-sectional area of ​​the sealing gasket , and the effective cross-sectional area of ​​the sealing groove Calculate fill rate and fill rate As a threshold screening criterion; According to the free height of the sealing gasket and the height after assembly compression Calculate the compression ratio of the sealing gasket and the compression ratio As a threshold screening criterion; Based on the height change of the sealing gasket under constant load and temperature conditions Calculate creep variables and creep variables As a threshold screening criterion; The fill rate Compression ratio and creep variables A sealing parameter system is constructed as a constraint parameter for sealing performance and an optimization evaluation index.

[0011] Furthermore, the fill rate The calculation formula is: ; Compression ratio The calculation formula is: ; creep variables The calculation formula is: .

[0012] Further, step 20 includes: Construct a cross-sectional structural model of the double-ribbed sealing gasket and define the height of the first sealing rib. Width of the first sealing rib Height of the second sealing rib Width of the second sealing rib and the spacing between the two sealing ribs This forms a set of structural parameters: ; The structural parameter set Using the sealing parameter as the independent variable and the sealing parameter as the dependent variable, a mapping function between the structural parameters and the sealing parameter is established: ; in, The mapping relationship function is a functional relationship established through finite element analysis of sample data. By establishing a mapping relationship between the set of structural parameters and the sealing parameters, the structural parameters of the double-ribbed sealing gasket can be quantitatively adjusted and corrected during subsequent analysis and optimization.

[0013] Further, step 30 includes: Set material constitutive relations, boundary conditions, and load conditions consistent with actual assembly conditions, and solve the finite element analysis model; Obtain the contact stress distribution function of the sealing area And calculate the average contact stress. The calculation formula is as follows: ; in, For the effective contact area, Insignificant area elements during the integration process.

[0014] Further, step 40 includes: Preset multi-parameter joint performance threshold range, including contact stress threshold range Fill rate threshold range and compression ratio threshold range ; In the structural parameter set If the following constraints are met simultaneously, it will be retained as a candidate optimization structure: ; in, For the first Contact stress corresponding to the structural parameters of the group. For the first The fill rate corresponding to the group structure parameters For the first Compression ratio corresponding to group structure parameters. These are the lower and upper limits of the contact stress, respectively. These are the lower and upper limits of the fill rate threshold, respectively. These are the lower limit threshold and the upper limit threshold for compression ratio, respectively.

[0015] Further, step 50 includes: The selected candidate double-ribbed sealing gasket structures were verified by thermal shock tests, which conformed to the GMW3155 standard. The sealing gasket was subjected to multiple hot and cold cycles according to a preset temperature cycling curve to obtain the leakage rate. Compression permanent deformation rate and sealing retention rate The leakage rate Including mass leakage rate With volumetric leakage rate The mass leakage rate With volumetric leakage rate The calculation formulas are as follows: ; ; in The difference in the quality of the leaked medium before and after the test, For statistical purposes, Due to the volume difference of the leaking medium, The density of the leaking medium.

[0016] Furthermore, due to the change in density caused by temperature For a loop segment Integral average, volumetric leakage rate : ; in Instantaneous mass leakage rate, These are the start time and end time of the loop, respectively. Temperature-dependent density function, Temperature function over time Time element; The compressive permanent deformation rate The calculation formula is: ; in The free height before the experiment, The height compressed during the test, This refers to the recovery time after uninstallation. The altitude at the corresponding moment; The sealing retention rate The calculation formula is the ratio of the sealing capacity after the test to the sealing capacity before the test: ; in The average contact stress after the test. The average contact stress before the test.

[0017] Furthermore, the specific implementation conditions for the GMW3155 thermal shock test are as follows: Test medium: air or nitrogen, pressure 0.1-0.3 MPa; Temperature range: low temperature ,high temperature ; Cycle duration: 60 minutes per cycle, including 30 minutes at low temperature with a 10-second transition; and 30 minutes at high temperature with a 10-second transition. Number of cycles: 1000 cycles for basic verification, 3000 cycles for long-term reliability verification; Leakage rate testing employs helium mass spectrometry or pressure drop method, with high sensitivity. .

[0018] Further, step 60 includes: Calculate the performance deviation between finite element prediction results and thermal shock test results. ; ; in Leakage rate Compression permanent deformation, Seal retention rate , The leakage rate is predicted by the finite element method. The actual leakage rate measured in the experiment, The compressive permanent deformation rate predicted by finite element method. The experimentally measured compressive permanent deformation rate, The seal retention rate predicted by finite element method. The measured seal retention rate is represented by FE, which indicates the performance of the finite element prediction result, and EXP, which indicates the performance of the test result.

[0019] Furthermore, when the deviation Exceeding the preset threshold At that time, the parameters of the doubly reinforced structure are corrected using a gradient descent algorithm based on the direction and amount of deviation; the formula for the gradient descent algorithm is as follows: ; in: This is the corrected structure parameter vector. This is the structure parameter vector before correction. For learning rate, Jacobian matrix The false rebellion, This is the vector of performance parameters predicted by the finite element method. This is a vector of experimentally measured performance parameters. Performance deviation vector, the first Jacobian matrix Element matrix elements Calculated using the finite difference method, the convergence criterion is iteration. Or it can reach the maximum number of iterations, 10.

[0020] Further, step 70 includes storing the corrected structural parameters, sealing parameters, finite element analysis results, and thermal shock test results of the double-ribbed gasket into the product database, and establishing an optimization rule function for back-deriving the double-ribbed structural parameters based on the correspondence between historical structural parameters, sealing parameters, and performance evaluation results. ; in, This represents the target structural parameter vector that meets the sealing performance requirements. Represents the target sealing performance parameter vector; This refers to the process of inversely solving for structural parameters under given target sealing performance parameters.

[0021] Compared with the prior art, one or more embodiments of the present invention may have the following advantages: (1) By establishing a sealing parameter system and establishing a quantitative mapping relationship between it and the structural parameters of the double-ribbed sealing gasket, this invention effectively reduces the dependence of the sealing gasket structure design on engineering experience and improves the repeatability and consistency of the structural design. (2) This invention organically combines finite element analysis with thermal shock testing conforming to GMW3155 standards, and through a closed-loop process of “threshold screening - thermal shock verification - deviation correction - iterative verification - back-entry into the database”, the number of candidates can be reduced after the closed loop, the development cycle is shortened, and the repeatable optimization of the double-ribbed sealing gasket structural parameters is realized, which significantly improves the reliability of structural optimization. (3) The present invention introduces a multi-parameter joint threshold screening mechanism, which enables the sealing gasket structure to meet the design requirements in multiple key indicators such as contact stress, filling rate and compression rate at the same time, effectively avoiding the potential sealing risks brought about by single indicator optimization; (4) This invention stores and utilizes historical structural parameters and performance data through a product database to form parameter back-reasoning and optimization decision rules, providing data support for the subsequent cylinder head cover sealing gasket structure design, shortening the development cycle and reducing trial and error costs. Attached Figure Description

[0022] Figure 1 This is a flowchart of the method for multi-parameter threshold screening and thermal shock closed-loop optimization of cylinder head cover double-rib sealing gasket; Figure 2 This is a schematic diagram of the cross-sectional structure of one type of double-ribbed sealing gasket; Figure 3 This is a schematic diagram of another type of double-ribbed sealing gasket cross-section structure; Figure 4This is a schematic diagram of the stress distribution of one type of cylinder head cover gasket; a is a finite element internal stress distribution diagram of the cylinder head cover gasket, and b is a finite element contact stress distribution diagram of the cylinder head cover gasket. Figure 5 This is another schematic diagram of the stress distribution of the cylinder head cover gasket; where a is the finite element internal stress distribution diagram and b is the finite element contact stress distribution diagram of the cylinder head cover gasket. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be described in further detail below with reference to the embodiments and accompanying drawings.

[0024] like Figure 1 The image shows a multi-parameter threshold screening and thermal shock closed-loop optimization method for the cylinder head cover double-rib gasket, including: Step 10. Obtain the initial cross-sectional structural parameters and assembly condition parameters of the cylinder head cover double-rib gasket, and establish a sealing parameter system; Step 20. Construct a structural parameter model of the double-ribbed sealing gasket and establish the mapping relationship between the structural parameters and the sealing parameters; Step 30. Establish a finite element analysis model including the gasket, cylinder head cover and mounting surface based on the structural parameter model of the double-ribbed gasket; Step 40. Extract the finite element analysis results and compare them with the preset multi-parameter joint performance threshold range; Step 50. Perform thermal shock tests on the selected candidate double-ribbed sealing gasket structures to verify their validity; Step 60. Calculate the performance deviation between the finite element prediction results and the experimental results; Step 70. Store the structural parameters, corresponding sealing parameters, and performance evaluation results verified by the thermal shock test into the product database; Step 80. Based on the finite element analysis results verified by thermal shock tests, the structural parameters of the double-ribbed gasket are finally optimized and adjusted to determine the target structural parameter combination that meets the sealing performance requirements, and the optimized results of the cylinder head cover gasket structure are output.

[0025] Step 10 above specifically includes: The initial cross-sectional structural parameters and assembly condition parameters of the cylinder head cover gasket are obtained. The gasket cross-section is then parametrically described, establishing a sealing parameter system to characterize its sealing performance. These sealing parameters include, but are not limited to, fill rate, compression ratio, and creep. Specifically: the fill rate characterizes the matching relationship between the gasket cross-section and the sealing groove; the compression ratio characterizes the degree of compression of the gasket in the assembled state; and the creep characteristic characterizes the deformation characteristics of the gasket under long-term load and temperature. The cross-sectional area of ​​the gasket is then obtained. Effective cross-sectional area of ​​the sealing groove Free height of sealing gasket and the height after assembly compression ; Based on the cross-sectional area of ​​the sealing gasket , and the effective cross-sectional area of ​​the sealing groove Calculate fill rate and fill rate As a threshold screening metric; its fill rate The calculation formula is as follows: ; According to the free height of the sealing gasket and the height after assembly compression Calculate the compression ratio of the sealing gasket and the compression ratio As a threshold screening metric, its compression ratio is calculated using the following formula: ; Based on the height change of the sealing gasket under constant load and temperature conditions Calculate creep variables and creep variables As a threshold screening metric; creep variable The calculation formula is: ; The fill rate Compression ratio and creep variables A sealing parameter system is constructed as a constraint parameter for sealing performance and an optimization evaluation index.

[0026] Step 20 above specifically includes: like Figure 2 , Figure 3 As shown, a structural parameter model of the double-ribbed cylinder head cover gasket is constructed based on the aforementioned sealing parameter system. The cross-sectional structure of the gasket is parametrically modeled. In the illustration, the top widths are "2.9" and "3.59", representing the horizontal distance (effective contact width) between the two inclined surfaces at the top, affecting the pressure per unit area and sealing performance. Dimensions "1.21" and "1.16" represent the top thickness, indicating the vertical height of the top protrusion, affecting the compression deformation and compression ratio. Dimensions "2.8" and "2.9" represent the overall height, indicating the height from the top to the lower base, affecting the compression ratio and filling rate. The double-ribbed structure includes a first sealing rib (main sealing rib) and a second sealing rib (auxiliary sealing rib). A cross-sectional structural model of the double-ribbed gasket is constructed, defining the height of the first sealing rib. Width of the first sealing rib Height of the second sealing rib Width of the second sealing rib and the spacing between the two sealing ribs This forms a set of structural parameters: ; Height of the first sealing rib Preferred range: [0.4, 1.0] mm; Optimal range: [0.5, 0.8] mm. Width of the first sealing rib Preferred range: [1.0, 2.5] mm; Optimal range: [1.2, 2.0] mm. Second sealing rib height Preferred range: [0.3, 0.9] mm; Optimal range: [0.4, 0.7] mm. Second sealing rib width Preferred range: [0.8, 2.0] mm; Optimal range: [1.0, 1.8] mm. Spacing between two sealing ribs Preferred range: [1.0, 3.0] mm; Optimal range: [1.2, 2.0] mm. Using the set of structural parameters as independent variables and the sealing parameters as dependent variables, a mapping function between the structural parameters and the sealing parameters is established: ; in, ; By establishing a mapping relationship between the structural parameter set and the sealing parameters, the structural parameters of the double-ribbed sealing gasket can be quantitatively adjusted and corrected in subsequent analysis and optimization processes.

[0027] Step 30 above establishes a finite element analysis model including the gasket, cylinder head cover, and mounting surface based on the structural parameter model of the double-ribbed gasket. Figure 4 This is a schematic diagram of the stress distribution of one type of cylinder head cover gasket; a is a finite element internal stress distribution diagram of the cylinder head cover gasket, and b is a finite element contact stress distribution diagram of the cylinder head cover gasket. Figure 5 This is another schematic diagram of stress distribution for the cylinder head cover gasket; where a is the finite element internal stress distribution diagram, and b is the finite element contact stress distribution diagram for the cylinder head cover gasket; in the finite element analysis process, the material constitutive relation, boundary conditions, and contact conditions are set according to the actual assembly conditions, and the stress and deformation behavior of the gasket in the assembly state is simulated and calculated. The specific implementation methods of each step are as follows: Material constitutive relations: A hyperelastic constitutive model for rubber-based composite materials is established, and the Mooney-Rivlin model is used to describe the nonlinear mechanical behavior of the rubber material. The strain energy function is: ; in , To adapt to invariants, For the fluororubber material used, the material constant is: (volume ratio). , , (Incompressibility coefficient); This material parameter is completely consistent with the sealing gasket material system used in the subsequent thermal shock test, ensuring that the material benchmarks for simulation and experiment are consistent and reducing the performance deviation between the two.

[0028] Mesh generation strategy: A hybrid mesh strategy is adopted to ensure a balance between computational accuracy and efficiency: In the sealing rib region (high stress gradient region), C3D8H (eight-node hexahedral hybrid element) is used for local refinement with a mesh size of 0.5mm; In the body region, C3D8R (eight-node hexahedral reduced integral element) is used with a mesh size of 1.0mm; In the mesh transition region, C3D10 (ten-node tetrahedral element) is used to ensure mesh quality.

[0029] Contact conditions: The contact algorithm uses the penalty function method. The principal surface is set as the metal contact surface of the cylinder head cover and cylinder head, and the secondary surface is set as the rubber contact surface of the gasket. The gasket and cylinder head cover, and the gasket and cylinder head, maintain surface-to-surface contact. The coefficient of friction is... .

[0030] Boundary conditions: The lower surface is completely fixed to the cylinder head contact surface, and a uniform displacement load is applied to the upper surface to simulate bolt preload.

[0031] Simulation output: Obtain the contact stress distribution function of the sealed area. And calculate the average contact stress. The calculation formula is as follows: ; in, The effective contact area.

[0032] Step 40 includes: Preset multi-parameter joint performance threshold range, including contact stress threshold range Fill rate threshold range and compression ratio threshold range The specific threshold ranges are shown in Table 1.

[0033] In the structural parameter set If the following constraints are met simultaneously, it will be retained as a candidate optimization structure:

[0034] in, For the first Contact stress corresponding to the structural parameters of the group. For the first The fill rate corresponding to the group structure parameters For the first Compression ratio corresponding to group structure parameters. These are the lower and upper limits of the contact stress, respectively. These are the lower and upper limits of the fill rate threshold, respectively. These are the lower limit threshold and the upper limit threshold for compression ratio, respectively.

[0035] Among them: contact stress index: ; Fill rate metric: ; Compression ratio metrics: .

[0036] The multi-parameter joint screening mechanism avoids the potential risks of optimizing a single index, ensuring that candidate structures simultaneously meet the performance targets across multiple metrics; when the structural parameter set... If the above-mentioned multi-parameter joint threshold condition is met, it is retained as a candidate optimization structure.

[0037] Step 50 specifically includes: The selected candidate double-ribbed sealing gasket structures were verified by thermal shock tests, which conformed to the GMW3155 standard. The sealing gasket was subjected to multiple hot and cold cycles according to a preset temperature cycling curve to obtain the leakage rate. Compression permanent deformation rate and sealing retention rate The leakage rate Including mass leakage rate With volumetric leakage rate The mass leakage rate With volumetric leakage rate The calculation formulas are as follows: ; ; in The difference in the quality of the leaked medium before and after the test, For statistical purposes, the time frame is specified.

[0038] Density changes due to temperature For a loop segment Integral average:

[0039] in Instantaneous mass leakage rate; The compressive permanent deformation rate The calculation formula is:

[0040] in The free height before the experiment, The height compressed during the test, This refers to the recovery time after uninstallation. The altitude at the corresponding moment; The sealing retention rate The calculation formula is the ratio of the sealing capacity after the test to the sealing capacity before the test: ; It reflects the degree to which the sealing ability is maintained after thermal shock. The average contact stress after the test. The average contact stress before the test.

[0041] Its qualification criteria: mass leakage rate (Helium mass spectrometry leak detection method); Compression permanent deformation rate ; Sealing retention rate .

[0042] The specific implementation conditions for the GMW3155 thermal shock test are as follows: Test medium: air or nitrogen, pressure 0.1-0.3 MPa; Temperature range: low temperature ,high temperature ; Cycle duration: 60 minutes per cycle, including 30 minutes at low temperature with a 10-second transition; and 30 minutes at high temperature with a 10-second transition. Number of cycles: 1000 cycles for basic verification, 3000 cycles for long-term reliability verification; Leakage rate testing employs helium mass spectrometry or pressure drop method, with high sensitivity. .

[0043] Step 60 specifically includes: Calculate the performance deviation between finite element prediction results and thermal shock test results. ; ; The weighting coefficients are set as follows: w 1 =0.55 (leakage rate)w 2 =0.3 (compression permanent deformation), w 3 =0.15 (sealing retention rate), which meets the requirements. , The leakage rate is predicted by the finite element method. The actual leakage rate measured in the experiment, The compressive permanent deformation rate predicted by finite element method. The experimentally measured compressive permanent deformation rate, The seal retention rate predicted by finite element method. The measured seal retention rate is represented by FE, which indicates the performance of the finite element prediction result, and EXP, which indicates the performance of the test result.

[0044] When the deviation Exceeding the preset threshold At that time, the parameters of the bi-ribbed structure are corrected using a gradient descent algorithm based on the direction and amount of deviation. Correction threshold ; Parameter correction algorithm: when At that time, a gradient descent algorithm based on the pseudo-inverse of the Jacobian matrix is ​​used for parameter correction: ; in: This is the corrected structure parameter vector. This is the structure parameter vector before correction. The learning rate controls the correction step size. For Jacobian matrices, This is the vector of performance parameters predicted by the finite element method. This is a vector of experimentally measured performance parameters. Performance deviation vector, the first Jacobian matrix Element matrix elements Calculated using the finite difference method:

[0045] for The Moore-Penrose pseudo-inverse ensures that parameter corrections are made in the direction that reduces the bias. For the first One performance parameter, For the first One structural parameter, For the first A tiny increment of a structural parameter, These are the performance parameter values ​​after the disturbance. These are the original performance parameter values.

[0046] Iterative convergence criteria: Master criterion, iteration Δ < 15%; Protection criterion: reaching the maximum number of iterations of 10; If convergence is not achieved, return to step 30 and repeat the finite element analysis until the convergence condition is met.

[0047] Step 70 includes storing the corrected double-ribbed gasket structural parameters, sealing parameters, finite element analysis results, and thermal shock test results into the product database, and establishing an optimization rule function for back-deriving the double-ribbed structural parameters based on the correspondence between historical structural parameters, sealing parameters, and performance evaluation results. ; in, This represents the target structural parameter vector that meets the sealing performance requirements. Represents the target sealing performance parameter vector; This refers to the process of inversely solving the structural parameters under given target sealing performance parameters. In this embodiment, a structural parameter inverse optimization model is established based on historical bi-ribbed structural parameters, sealing parameters, and performance evaluation results in the product database.

[0048] Step 80 specifically includes: Optimize the objective function:

[0049] Constraints:

[0050] The optimization solution is obtained using Sequential Quadratic Programming (SQP) or a genetic algorithm, outputting the final optimized result of the cylinder head cover double-rib gasket structure, including complete geometric parameters, material specifications, and performance predictions; in the formula: For the set of structural parameters, ; Leakage rate index Leakage rate weighting coefficient This represents the actual leakage rate. The target leakage rate; Normalized leakage rate; Compression set index, Compression permanent deformation weighting coefficient Compression permanent deformation rate, Target permanent deformation rate Normalized value of permanent deformation; Sealing retention rate index Sealing retention rate weighting coefficient Actual seal retention rate The reciprocal of the seal retention rate.

[0051] The aforementioned sealing gasket uses a fluororubber FKM-based material system, comprising: 100 parts DuPont GBL-900, 25-35 parts N550 carbon black, 10-15 parts fumed silica A-200, 5-8 parts trioctyl trimellitate, 2-3 parts bisphenol AF, 0.5-1.0 parts benzyltriphenylphosphine chloride, 3-5 parts magnesium oxide, and 1-2 parts antioxidant TMQ; the material has a Shore A hardness of 70±5, a tensile strength ≥12 MPa, and a compression set (150℃×22h) ≤25%.

[0052] The present invention will be further described in detail below with reference to specific embodiments: Example 1: Optimized design of cylinder head cover sealing gasket for a 1.5T gasoline engine S1: Initial parameter acquisition and sealing parameter system establishment To address the cylinder head cover sealing requirements of a 1.5T gasoline engine, the initial structural parameters were obtained: Sealing groove dimensions: groove width 4.5mm, groove depth 3.0mm; Assembly conditions: bolt preload torque 12N·m, operating temperature .

[0053] Establish a sealing parameter system, with the target value set as follows: Fill rate F: 65%-85%, Compression rate C: 15%-35%, Creep .

[0054] S2: Construction of Parametric Model for Double-Reinforced Structure Based on design experience, an initial combination of structural parameters is generated (the initial candidate set of structural parameters is shown in Table 2):

[0055] S3: Finite Element Analysis A finite element model was established using ABAQUS software: Material model: Mooney-Rivlin hyperelastic model, C 10 =0.65 MPa, C 01 =0.16 MPa .

[0056] Mesh generation: C3D8H elements with a size of 0.5mm are used in the sealing rib area; C3D8R elements with a size of 1.0mm are used in the body area; and C3D10 elements are used in the transition area to balance accuracy and computational efficiency.

[0057] Contact settings: penalty function contact, friction coefficient 0.15.

[0058] The finite element simulation results are shown in Table 3:

[0059] S4: Multi-parameter joint threshold screening Based on the threshold stress range [1.5, 5.0] MPa, the fill rate [65%, 85%], and the compression rate [15%, 35%], the candidate structures are P1, P2, and P5.

[0060] S5: The selected candidate double-ribbed gasket structures meet the GMW3155 standard thermal shock test. Prototypes of the candidate structures were fabricated and subjected to 1000 thermal shock cycles. The results of the experiment are shown in Table 4:

[0061] S6: Simulation-Experiment Deviation Analysis and Correction Deviation analysis of scheme P2: Finite element prediction: , , ; Experimental measurements: , , ; Overall deviation: It needs to be corrected; Analysis of the cause of the deviation: Height of the second sealing rib in scheme P2 The value is too low, resulting in insufficient auxiliary sealing at high temperatures. A gradient descent algorithm is used to correct this. Correction direction: Increase Increase ; Correction amount: ,

[0062] New proposal:

[0063] Finite element analysis and experimental verification were performed again on P2'. Results: Finite element prediction: , , Experimental measurements: , , ; The requirements are met.

[0064] S7: Database Establishment and Parameter Inversion The validated data for schemes P1, P2', and P5 were stored in the product database to establish an initial backpropagation model. Based on the three sets of data, a linear regression equation was established:

[0065]

[0066]

[0067] The example only uses 3 sets of validation data to demonstrate the database construction method; in actual applications, a total of 30 sets are accumulated before training the regression model.

[0068] S8: Determine the optimal structure Considering both performance and manufacturability, P2' was ultimately determined to be the optimal solution. Structural parameters: , , , , ; Predictive performance: , , ; Actual verification shows that it meets the requirements of GMW3155 standard.

[0069] Example 2: Database-based parameter reverse inference application For the newly developed 2.0T engine, the target performance is: , , Using the database and reverse inference rules established in Example 1, the initial structural parameters are obtained: , , , , .

[0070] Finite element analysis and experimental verification showed that the initial scheme met the requirements, requiring only one iteration, and the development cycle was shortened by 60% compared with the traditional method.

[0071] While the embodiments disclosed in this invention are as described above, the content is merely for the purpose of facilitating understanding of the invention and is not intended to limit the invention. Any person skilled in the art to which this invention pertains may make any modifications and variations in form and detail of the implementation without departing from the spirit and scope disclosed herein; however, the scope of patent protection for this invention shall still be determined by the scope defined in the appended claims.

Claims

1. A method for threshold screening and thermal shock closed-loop optimization of cylinder head cover double-ribbed sealing gaskets, characterized in that, The method includes the following steps: Step 10: Obtain the initial cross-sectional structural parameters and assembly condition parameters of the cylinder head cover double-ribbed sealing gasket, and establish a sealing parameter system; Step 20: Construct a structural parameter model of the double-ribbed sealing gasket and establish a mapping relationship between structural parameters and sealing parameters; Step 30: Establish a finite element analysis model including the sealing gasket, cylinder head cover and mounting surface based on the structural parameter model of the double-ribbed sealing gasket; Step 40: Extract the finite element analysis results and compare them with the preset multi-parameter joint performance threshold range; Step 50: Perform thermal shock tests on the selected candidate double-ribbed sealing gasket structures to verify their validity. Step 60: Calculate the performance deviation between the finite element prediction results and the experimental results; Step 70: Store the structural parameters, corresponding sealing parameters, and performance evaluation results verified by the thermal shock test into the product database; Step 80: Based on the finite element analysis results verified by thermal shock tests, the structural parameters of the double-ribbed gasket are finally optimized and adjusted to determine the target structural parameter combination that meets the sealing performance requirements, and the optimized results of the cylinder head cover gasket structure are output.

2. The cylinder head cover double-rib sealing gasket threshold screening and thermal shock closed-loop optimization method according to claim 1, characterized in that, Step 10 includes: The cross-sectional structural parameters of the cylinder head cover gasket include the cross-sectional area of ​​the gasket. Effective cross-sectional area of ​​sealing groove Free height of sealing gasket The cylinder head cover sealing gasket assembly parameters include the height after assembly compression. ; Based on the cross-sectional area of ​​the sealing gasket , and the effective cross-sectional area of ​​the sealing groove Calculate fill rate and fill rate As a threshold screening criterion; According to the free height of the sealing gasket and the height after assembly compression Calculate the compression ratio of the sealing gasket and the compression ratio As a threshold screening criterion; Based on the height change of the sealing gasket under constant load and temperature conditions Calculate creep variables and creep variables As a threshold screening criterion; The fill rate Compression ratio and creep variables A sealing parameter system is constructed as a constraint parameter for sealing performance and an optimization evaluation index.

3. The cylinder head cover double-rib sealing gasket threshold screening and thermal shock closed-loop optimization method according to claim 2, characterized in that, The fill rate The calculation formula is: ； Compression ratio The calculation formula is: ； creep variables The calculation formula is: 。 4. The cylinder head cover double-rib sealing gasket threshold screening and thermal shock closed-loop optimization method according to claim 1, characterized in that, Step 20 includes: Construct a cross-sectional structural model of the double-ribbed sealing gasket and define the height of the first sealing rib. Width of the first sealing rib Height of the second sealing rib Width of the second sealing rib and the spacing between the two sealing ribs This forms a set of structural parameters: ； The structural parameter set Using the sealing parameter as the independent variable and the sealing parameter as the dependent variable, a mapping function between the structural parameters and the sealing parameter is established: ； in, The mapping relationship function is a functional relationship established through finite element analysis of sample data. By establishing a mapping relationship between the set of structural parameters and the sealing parameters, the structural parameters of the double-ribbed sealing gasket can be quantitatively adjusted and corrected during subsequent analysis and optimization.

5. The cylinder head cover double-rib sealing gasket threshold screening and thermal shock closed-loop optimization method according to claim 1, characterized in that, Step 30 includes: Set material constitutive relations, boundary conditions, and load conditions consistent with actual assembly conditions, and solve the finite element analysis model; Obtain the contact stress distribution function of the sealing area And calculate the average contact stress. The calculation formula is as follows: ； in, For the effective contact area, Insignificant area elements during the integration process.

6. The cylinder head cover double-rib sealing gasket threshold screening and thermal shock closed-loop optimization method according to claim 1, characterized in that, Step 40 includes: Preset multi-parameter joint performance threshold range, including contact stress threshold range Fill rate threshold range and compression ratio threshold range ; In the structural parameter set If the following constraints are met simultaneously, it will be retained as a candidate optimization structure: ； in, For the first Contact stress corresponding to the structural parameters of the group. For the first The fill rate corresponding to the group structure parameters For the first Compression ratio corresponding to group structure parameters. These are the lower and upper limits of the contact stress, respectively. These are the lower and upper limits of the fill rate threshold, respectively. These are the lower limit threshold and the upper limit threshold for compression ratio, respectively.

7. The cylinder head cover double-rib sealing gasket threshold screening and thermal shock closed-loop optimization method according to claim 1, characterized in that, Step 50 includes: The selected candidate double-ribbed sealing gasket structures were verified by thermal shock tests, which conformed to the GMW3155 standard. The sealing gasket was subjected to multiple hot and cold cycles according to a preset temperature cycling curve to obtain the leakage rate. Compression permanent deformation rate and sealing retention rate The leakage rate Including mass leakage rate With volumetric leakage rate The mass leakage rate With volumetric leakage rate The calculation formulas are as follows: ； ； in The difference in the quality of the leaked medium before and after the test, For statistical purposes, Due to the volume difference of the leaking medium, The density of the leaking medium.

8. The cylinder head cover double-rib sealing gasket threshold screening and thermal shock closed-loop optimization method according to claim 7, characterized in that, Density changes due to temperature For a loop segment Integral average, volumetric leakage rate : ； in Instantaneous mass leakage rate, These are the start time and end time of the loop, respectively. Temperature-dependent density function Temperature function over time Time element; The compressive permanent deformation rate The calculation formula is: ； in The free height before the test, The height compressed during the test, This refers to the recovery time after uninstallation. The altitude at the corresponding moment; The sealing retention rate The calculation formula is the ratio of the sealing capacity after the test to the sealing capacity before the test: ； in The average contact stress after the test. The average contact stress before the test.

9. The cylinder head cover double-rib sealing gasket threshold screening and thermal shock closed-loop optimization method according to claim 7, characterized in that, The specific implementation conditions for the GMW3155 thermal shock test are as follows: Test medium: air or nitrogen, pressure 0.1-0.3 MPa; Temperature range: low temperature ,high temperature ; Cycle duration: 60 minutes per cycle, including 30 minutes at low temperature with a 10-second transition; and 30 minutes at high temperature with a 10-second transition. Number of cycles: 1000 cycles for basic verification, 3000 cycles for long-term reliability verification; Leakage rate testing employs helium mass spectrometry or pressure drop method, with high sensitivity. .

10. The method for threshold screening and thermal shock closed-loop optimization of the cylinder head cover double-ribbed sealing gasket according to claim 1, characterized in that, Step 60 includes: Calculate the performance deviation between finite element prediction results and thermal shock test results. ; ； in Leakage rate Compression permanent deformation, Seal retention rate , The leakage rate is predicted by the finite element method. The actual leakage rate measured in the experiment, The compressive permanent deformation rate predicted by finite element method. The experimentally measured compressive permanent deformation rate, The seal retention rate predicted by finite element method. The measured seal retention rate is represented by FE, which indicates the performance of the finite element prediction result, and EXP, which indicates the performance of the test result.

11. The cylinder head cover double-rib sealing gasket threshold screening and thermal shock closed-loop optimization method according to claim 10, characterized in that, When the deviation Exceeding the preset threshold At that time, the parameters of the doubly reinforced structure are corrected using a gradient descent algorithm based on the direction and amount of deviation; the formula for the gradient descent algorithm is as follows: ； in: This is the corrected structure parameter vector. This is the structure parameter vector before correction. For learning rate, Jacobian matrix The false rebellion, This is the vector of performance parameters predicted by the finite element method. This is a vector of experimentally measured performance parameters. Performance deviation vector, the first Jacobian matrix Element matrix elements Calculated using the finite difference method, the convergence criterion is iteration. Or it can reach the maximum number of iterations, 10.

12. The cylinder head cover double-rib sealing gasket threshold screening and thermal shock closed-loop optimization method according to claim 11, characterized in that, Step 70 includes storing the corrected double-ribbed gasket structural parameters, sealing parameters, finite element analysis results, and thermal shock test results into the product database, and establishing an optimization rule function for back-deriving the double-ribbed structural parameters based on the correspondence between historical structural parameters, sealing parameters, and performance evaluation results. ； in, This represents the target structural parameter vector that meets the sealing performance requirements. Represents the target sealing performance parameter vector; This refers to the process of inversely solving for structural parameters under given target sealing performance parameters.

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