Efficient optimization design method for external supporting body of cylinder sleeve of internal combustion engine

Abstract

The invention provides an efficient optimization design method for an external support body of an internal combustion engine cylinder sleeve. The method comprises the following steps: acquiring vibration characteristics of the cylinder sleeve under typical working conditions through a finite element analysis method; according to the knocking transmission characteristics, the cylinder sleeve is internally and externally intercepted through a sub-model method, and a reasonable sub-model is obtained; the knocking response of the inner surface of the cylinder sleeve and the average knocking response of the supporting body outer connecting structure are extracted; establishing a mathematical optimization model of the outer support body of the cylinder sleeve; optimizing a genetic algorithm; outputting an optimal result; judging a result; and outputting a final optimization result. According to the method, the sub-model is formed through boundary interception, the time cost is reduced in the optimization iteration process, and a shorter design period is provided for the design of an external supporting body product of an internal combustion engine cylinder sleeve; the load boundaries established by the sub-models adopt equivalent loads under actual typical working conditions, so that the method is not only suitable for actual engineering application, but also simplifies the complexity of the load boundaries, so that the design is more efficient.

Description

Technical Field

[0001] The invention relates to the technical field of vibration reduction and noise reduction of internal combustion engines, and in particular to a high-efficiency optimization design method for an outer support body of a cylinder liner of an internal combustion engine. Background Art

[0002] As the main power source and noise source of ships and automobiles, internal combustion engines have a significant impact on the total noise level. In addition, in terms of aviation, road and rail transportation technology, the control of noise emissions is the core of social acceptance and economic competitiveness. Therefore, it is urgent to study methods and measures to reduce the noise level of internal combustion engines. After analyzing the various noise sources of internal combustion engines, it can be seen that the noise components of internal combustion engines are complex and there are many noise sources. The noise mainly comes from the working process of the corresponding components, such as combustion, piston knocking, fuel injection, gear meshing, injection pump, valve knocking, etc. The vibration noise of the piston knocking on the cylinder liner is one of the main noise sources of the internal combustion engine. By reducing the vibration noise of the piston knocking on the cylinder liner, the total vibration noise of the internal combustion engine will be significantly reduced.

[0003] In order to reduce the vibration noise caused by the piston hitting the cylinder liner, in actual engineering applications, in addition to optimizing the design of the piston (excitation source), the external support body of the cylinder liner (transmission path) also plays an important role. At present, the external support body of the cylinder liner is mainly distributed at the upper and lower ends of the cylinder liner. This is based on experience design, which shows that there is still a lot of design space for the design of the support body. In addition, the structure of the cylinder liner of the internal combustion engine is complex, and there is a problem of large amount of calculation in solving dynamic problems such as vibration. And the general optimization measures are only to adjust the position and size of the support body through enumeration and trial and error. Such a design is not systematic, not only consumes a lot of time cost, but the design result may not be optimal. Summary of the invention

[0004] In view of the problems existing in the prior art, the present application proposes a method for efficiently optimizing the design of an outer support body of a cylinder liner of an internal combustion engine, comprising the following steps:

[0005] The vibration characteristics of the cylinder liner under typical working conditions are obtained by finite element analysis method;

[0006] According to the knocking transmission characteristics, the cylinder liner is cut inside and outside by using the sub-model method to obtain a reasonable sub-model;

[0007] Extract the knock response of the inner surface of the cylinder liner and the average knock response of the external connection structure of the support body;

[0008] Establish a mathematical optimization model for the outer support of the cylinder liner;

[0009] Genetic algorithm optimization;

[0010] Output the best result;

[0011] Result determination;

[0012] Output the final optimization results.

[0013] Furthermore, obtaining the vibration characteristics of the cylinder liner under typical working conditions through the finite element analysis method includes: establishing the geometric model required for the vibration analysis of the cylinder liner of the internal combustion engine, and performing finite element meshing on it, and finally performing the finite element analysis method to obtain the knock transmission characteristics of the cylinder liner under typical working conditions.

[0014] Furthermore, obtaining a reasonable sub-model includes: selecting the cylinder liner, the support body and the external connection structure of the support body as the sub-model, and the external connection structure should not be too large.

[0015] Furthermore, extracting the knock response of the inner surface of the cylinder liner and the average knock response of the supporting external connection structure includes:

[0016] The knock response of the inner surface of the cylinder liner is A in The average knock response of the supporting external connection structure is A out ;

[0017] According to the finite element analysis results, the knock response A of N nodes on the inner surface of the cylinder liner is extracted. in， , the interpolation and merging of the response results is equivalent to A ineff , the equivalent load node becomes N eff =(1 / 4~1 / 6)N, and can satisfy formula (1) and formula (2)

[0018]

[0019] In formula (2), To support the average tapping response of the in vitro connection structure, It is the equivalent average knocking response of the supporting external connection structure under the equivalent input load.

[0020] Furthermore, the mathematical optimization model of the cylinder liner outer support is established including:

[0021] According to the knocking model extraction after the structural finite element analysis of the internal combustion engine cylinder liner, the mathematical optimization model of the cylinder liner outer support is constructed using the following formula:

[0022]

[0023] In formula (3), f(X) is the optimization target and also the transmission loss coefficient of the tapping response, X is the density value of the design domain, n is the number of design variables, and Ku = ω 2 Mu indicates that the basic dynamic balance must be satisfied during the structural analysis and calculation, where K is the stiffness matrix of the structure, u is the displacement matrix of the structure, ω is the circular frequency, and M is the mass matrix.

[0024] Furthermore, genetic algorithm optimization includes:

[0025] Generate an initial population P0=20;

[0026] Finite element analysis of the sub-model structure of the population;

[0027] The results of the finite element analysis of the population were evaluated;

[0028] Select individuals with better performance and keep them;

[0029] Perform crossover and mutation on the retained individuals.

[0030] Furthermore, outputting the optimal result includes: in the optimization of the outer support of the cylinder liner of the internal combustion engine, outputting the optimal result, recording the current iteration step as i, and saving its objective function f i (X).

[0031] Furthermore, the result judgment includes: iterating for more than 10 steps, and using the relative change rate er of the transmission loss coefficient of the tapping response in the last 10 steps to judge whether it has converged, as shown in formula (4):

[0032]

[0033] If convergence occurs (er<0.01), then S8 is performed to output the optimized model as the final result. Otherwise, the calculation returns to step ② of S5 and is recalculated.

[0034] Furthermore, the final optimization results are output including:

[0035] Firstly, a finite element model for the vibration analysis of the internal combustion engine cylinder is established, and the knock transmission characteristics of the cylinder liner under typical working conditions are obtained by the finite element analysis method.

[0036] According to the knocking transmission characteristics, the sub-model method is used to intercept the inside and outside of the cylinder liner to obtain a reasonable sub-model. The cylinder liner, support body and the external connection structure of the support body are selected as the sub-model. The external connection structure should not be too large.

[0037] The input knocking transfer response is equivalent, and the cylinder liner inner wall knocking response input load equivalent effect selects 4-6 node responses to be equivalent to one load.

[0038] Furthermore, when extracting the knock response of the inner surface of the cylinder liner and the average knock response of the external connection structure of the support body, the sum of the equivalent loads should be equal to the sum of the actual loads, and the relative error between the average output response after the equivalent load and the actual average output response should be less than 5%.

[0039] The efficient optimization design method for the outer support of the cylinder liner of an internal combustion engine provided by the present invention has the following beneficial effects compared with the prior art:

[0040] The efficient optimization design method for the outer support of the cylinder liner of an internal combustion engine proposed in the present invention forms a sub-model by boundary interception, which reduces the time cost in the process of optimization iteration and provides a shorter design cycle for the design of the outer support product of the cylinder liner of an internal combustion engine; the load boundary established by the sub-model adopts the equivalent load under actual typical working conditions, which is not only suitable for actual engineering applications but also simplifies the complexity of the load boundary, and also makes the design more efficient; the full design domain of the cylinder liner from top to bottom is adopted, which provides more design space for the design of the support body and can greatly improve its vibration reduction and noise reduction performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is a flow chart of the method of the present invention;

[0042] Figure 2 It is a schematic diagram of the cylinder composition of the internal combustion engine of the present invention;

[0043] Figure 3 This is an equivalent schematic diagram of the input response load of the present invention;

[0044] Figure 4 Schematic diagram of extraction and encoding of optimized design domain of the present invention. DETAILED DESCRIPTION

[0045] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described below in conjunction with the accompanying drawings and specific implementation methods.

[0046] The present application proposes a method for efficiently optimizing the design of an outer support body of a cylinder liner of an internal combustion engine, the method specifically comprising the following steps:

[0047] S1: Obtain the vibration characteristics of the cylinder liner under typical working conditions through finite element analysis method:

[0048] Establish the geometric model required for the vibration analysis of the cylinder liner of the internal combustion engine, divide it into finite element meshes, and finally use the finite element analysis method to obtain the knock transmission characteristics of the cylinder liner under typical working conditions;

[0049] S2: According to the knocking transmission characteristics, the sub-model method is used to intercept the inside and outside of the cylinder liner to obtain a reasonable sub-model:

[0050] The cylinder liner, support body and support body external connection structure are selected as sub-models. The external connection structure should not be too large. A three-layer finite element mesh of the external support body connection structure can be selected to reduce the amount of calculation. Figure 2 As shown;

[0051] S3: Extract the knock response A of the inner surface of the cylinder liner in The average knock response of the supporting external connection structure is A out :

[0052] According to the finite element analysis results, the knock response A of all nodes (N nodes) on the inner surface of the cylinder liner is extracted. in， , the interpolation and merging of the response results is equivalent to A ineff , the equivalent load node becomes N eff =(1 / 4~1 / 6)N, details are as attached Figure 3 As shown, and can satisfy formula (1) and formula (2)

[0053]

[0054] In formula (2), To support the average tapping response of the in vitro connection structure, It is the equivalent average knocking response of the supporting external connection structure under the equivalent input load;

[0055] S4: Establishing the mathematical optimization model of the cylinder liner outer support:

[0056] According to the knocking model extraction after the structural finite element analysis of the internal combustion engine cylinder liner, the mathematical optimization model of the cylinder liner outer support is constructed using the following formula:

[0057]

[0058] In formula (3), f(X) is the optimization target and also the transmission loss coefficient of the knocking response. X is the density value of the design domain. By discretizing the design variables in the extracted design domain, the number of design variables is discretized into n, as shown in the attached figure. Figure 4 shown.

[0059] Ku=ω 2 Mu indicates that the basic dynamic balance must be satisfied during the structural analysis and calculation, where K is the stiffness matrix of the structure, u is the displacement matrix of the structure, ω is the circular frequency, and M is the mass matrix;

[0060] S5: Genetic Algorithm Optimization

[0061] By encoding discrete design variables, individual genes are formed, such as Figure 4 As shown. Then optimize the model through the following steps:

[0062] ① Generate an initial population P0=20;

[0063] ② Conduct finite element analysis on the sub-model structure of the population;

[0064] ③ Evaluate the finite element analysis results of the population;

[0065] ④ Select individuals with better performance and retain them;

[0066] ⑤Perform crossover and mutation on the retained individuals.

[0067] S6: Output the optimal result:

[0068] In the optimization of the external support of the cylinder liner of the internal combustion engine, the optimal result is output, the current iteration step is recorded as i, and its objective function f is saved i (X).

[0069] S7: Result determination:

[0070] Iterate for more than 10 steps, and use the relative change rate er of the transmission loss coefficient of the last 10 steps to judge whether it has converged, as shown in formula (4):

[0071]

[0072] If convergence occurs (er<0.01), then S8 is performed to output the optimized model as the final result. Otherwise, the calculation returns to step ② of S5 and is recalculated.

[0073] S8: Output the final optimization results

[0074] When the convergence conditions are met, the optimization model can be output as the final result.

[0075] In summary, the above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited thereto. All equivalent changes and modifications made according to the patent scope of the present invention and the contents of the specification are within the scope covered by the patent of the present invention.

Claims

1. A highly efficient optimization design method for an external support of a cylinder liner of an internal combustion engine, characterized in that: The following steps are involved: The vibration characteristics of the cylinder liner under typical working conditions are obtained by finite element analysis method; According to the knocking transmission characteristics, the cylinder liner is cut inside and outside by using the sub-model method to obtain a reasonable sub-model; Extract the knock response of the inner surface of the cylinder liner and the average knock response of the external connection structure of the support body; Establish a mathematical optimization model for the outer support of the cylinder liner; Genetic algorithm optimization; Output the best result; Result determination; Output the final optimization results.

2. The method according to claim 1, characterized in that Obtaining the vibration characteristics of the cylinder liner under typical working conditions through the finite element analysis method includes: establishing the geometric model required for the vibration analysis of the cylinder liner of the internal combustion engine, performing finite element meshing on it, and finally performing the finite element analysis method to obtain the knock transmission characteristics of the cylinder liner under typical working conditions.

3. The method according to claim 2, characterized in that Obtaining a reasonable sub-model includes: selecting the cylinder liner, the support body and the external connection structure of the support body as the sub-model, and the external connection structure should not be too large.

4. The method according to claim 3, characterized in that Extracting the knock response of the inner surface of the cylinder liner and the average knock response of the supporting external connection structure includes: The knock response of the inner surface of the cylinder liner is A in The average knock response of the supporting external connection structure is A out ; According to the finite element analysis results, the knock response A of N nodes on the inner surface of the cylinder liner is extracted. in， , the interpolation and merging of the response results is equivalent to A ineff , the equivalent load node becomes N eff =(1 / 4~1 / 6)N, and can satisfy formula (1) and formula (2) In formula (2), To support the average tapping response of the in vitro connection structure, It is the equivalent average knocking response of the supporting external connection structure under the equivalent input load.

5. The method according to claim 4, characterized in that The mathematical optimization model of the cylinder liner outer support is established including: According to the knocking model extraction after the structural finite element analysis of the internal combustion engine cylinder liner, the mathematical optimization model of the cylinder liner outer support is constructed using the following formula: In formula (3), f(X) is the optimization target and also the transmission loss coefficient of the tapping response, X is the density value of the design domain, n is the number of design variables, and Ku = ω 2 Mu indicates that the basic dynamic balance must be satisfied during the structural analysis and calculation, where K is the stiffness matrix of the structure, u is the displacement matrix of the structure, ω is the circular frequency, and M is the mass matrix.

6. The method according to claim 5, characterized in that Genetic algorithm optimization includes: Generate an initial population P0=20; Finite element analysis of the sub-model structure of the population; The results of the finite element analysis of the population were evaluated; Select individuals with better performance and keep them; Perform crossover and mutation on the retained individuals.

7. The method according to claim 6, characterized in that Outputting the optimal result includes: in the optimization of the external support of the cylinder liner of the internal combustion engine, outputting the optimal result, recording the current iteration step as i, and saving its objective function f i (X).

8. The method according to claim 7, characterized in that The result judgment includes: iterating for more than 10 steps, and using the relative change rate er of the transmission loss coefficient of the knocking response in the last 10 steps to judge whether it has converged, as shown in formula (4): If convergence occurs (er<0.01), then S8 is performed to output the optimized model as the final result. Otherwise, the calculation returns to step ② of S5 and is recalculated.

9. The method according to claim 8, characterized in that The final optimization results include: Firstly, a finite element model for the vibration analysis of the internal combustion engine cylinder is established, and the knock transmission characteristics of the cylinder liner under typical working conditions are obtained by the finite element analysis method. According to the knocking transmission characteristics, the sub-model method is used to intercept the inside and outside of the cylinder liner to obtain a reasonable sub-model. The cylinder liner, support body and the external connection structure of the support body are selected as the sub-model. The external connection structure should not be too large. The input knocking transfer response is equivalent, and the cylinder liner inner wall knocking response input load equivalent effect selects 4-6 node responses to be equivalent to one load.

10. The method according to claim 9, characterized in that: When extracting the knock response of the inner surface of the cylinder liner and the average knock response of the external connection structure of the support body, the sum of the equivalent loads should be equal to the sum of the actual loads, and the relative error between the average output response after the equivalent load and the actual average output response should be less than 5%.

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