A method and device for designing a structure of a planetary carrier

Abstract

The application discloses a structural design method and device of a planet carrier, and relates to the technical field of gear box planet carriers, and comprises the following steps: determining a maximum equivalent stress value and a maximum gear shaft torsion angle under a limit working condition according to the structure of a historical planet carrier; performing topology optimization with a volume fraction, the maximum equivalent stress value and the maximum gear shaft torsion angle as constraints and minimum flexibility as a target to obtain a topology-optimized planet carrier structure; performing parameter optimization on structural parameters based on the mapping relationship between the planet carrier structural parameters and the performance concerned; and manufacturing the planet carrier according to the topology-optimized planet carrier structure and the parameter-optimized structural parameters when the equivalent stress value and the gear shaft torsion angle corresponding to the parameter-optimized structural parameters are smaller than the equivalent stress value and the gear shaft torsion angle before the parameter optimization. The rigidity and the strength are considered simultaneously, and each structural parameter in the planet carrier is adjusted under the constraints, the topology optimization and the parameter optimization are combined, and the size of the planet carrier is more accurate.

Description

Technical Field

[0001] This invention relates to the field of planetary carrier technology for gearboxes, and in particular to a structural design method and apparatus for a planetary carrier. Background Technology

[0002] To meet the ever-increasing market demand and the accelerating pace of product iteration, rapid structural optimization strategies have become essential. A common lightweight design strategy in industrial design involves designers adjusting individual structural parameters of the planetary carrier based on past experience. The adjusted design is then verified using finite element analysis. If the stiffness and strength performance requirements are not met, the structural parameters need to be modified again until they are satisfied before being used as the dimensions of the planetary carrier. Therefore, related technologies often require multiple modifications and iterations to obtain a satisfactory solution, resulting in low design efficiency. Summary of the Invention

[0003] The purpose of this invention is to provide a structural design method and apparatus for planetary carriers that considers both stiffness and strength, and adjusts various structural parameters in the planetary carrier under constraints. By combining topology optimization and parameter optimization, the dimensions of the obtained planetary carrier are more accurate.

[0004] To solve the above-mentioned technical problems, the present invention provides a structural design method for a planetary carrier, comprising:

[0005] The maximum equivalent stress and maximum gear shaft torsion angle under extreme operating conditions are determined based on the historical structure of the planetary carrier. The maximum equivalent stress characterizes the strength of the planetary carrier, and the maximum gear shaft torsion angle characterizes the stiffness of the planetary carrier.

[0006] With volume fraction, maximum equivalent stress value, and maximum gear shaft torsional angle as constraints, topology optimization is performed with minimum flexibility as the optimization objective to obtain the structure of the planetary carrier after topology optimization. The flexibility is negatively correlated with the stiffness. The volume fraction is the ratio of the volume of the planetary carrier after topology optimization to the volume of the planetary carrier before topology optimization.

[0007] Determine the mapping relationship between the structural parameters of the planetary carrier and the performance of interest, including the mass of the planetary carrier, the equivalent stress value, and the torsional angle of the gear shaft;

[0008] Based on the mapping relationship, the structural parameters are optimized;

[0009] When the equivalent stress value and gear shaft torsion angle corresponding to the optimized structural parameters are less than the equivalent stress value and gear shaft torsion angle before parameter optimization, the planet carrier is manufactured according to the topology-optimized structure of the planet carrier and the optimized structural parameters.

[0010] On the other hand, the maximum equivalent stress and maximum gear shaft torsional angle under extreme conditions are determined based on the historical structure of the planetary carrier, including:

[0011] Based on the initial geometric model of the planetary carrier, load boundary conditions are added to the geometric model to establish the maximum equivalent stress value and maximum gear shaft torsion angle of the planetary carrier under extreme working conditions.

[0012] The expression for the maximum equivalent stress value is as follows: , This is the maximum equivalent stress value. , and The first, second, and third principal stresses are respectively, and the expression for the maximum gear shaft torsional angle is: θ is the maximum gear shaft torsional angle, Δ max For the maximum displacement along the X-axis of the local coordinate system, Δ min R is the minimum displacement along the X-axis of the local coordinate system, and R is the vertical distance from the center of the gear shaft mounting hole to the planet carrier rotation axis. The local coordinate system is established on the gear shaft, and the origin of the local coordinate system is located at the center of each gear shaft. The Z-axis points downward along the gear shaft axis, and the Y-axis points towards the center of the gear shaft along the planet carrier axis. The X-axis forms a right-handed coordinate system with the Y-axis and Z-axis.

[0013] On the other hand, topology optimization is performed with constraints of volume fraction, maximum equivalent stress value, and maximum gear shaft torsional angle, and with minimum compliance as the optimization objective, to obtain the topology-optimized structure of the planetary carrier, including:

[0014] Establish the topology optimization design region of the planet carrier, and remove material from the gear region of the planet carrier;

[0015] Add axisymmetric and radial draft manufacturing constraints to the topology optimization design region;

[0016] With volume fraction, maximum equivalent stress value and maximum gear shaft torsional angle as constraints, and minimum compliance as the optimization objective, the topology optimization design region is optimized.

[0017] Wherein, the maximum equivalent stress value is the maximum equivalent stress value after constraint characterization optimization which is less than the maximum equivalent stress value calculated in the initial scheme, and the maximum gear shaft torsion angle is the maximum gear shaft torsion angle after constraint characterization optimization which is less than the maximum gear shaft torsion angle calculated in the initial scheme.

[0018] On the other hand, determining the mapping relationship between the structural parameters of the planetary carrier and the performance of interest includes:

[0019] Based on the selection points determined by the Latin hypersolution method, a mapping relationship between the fitting structural parameters and the performance of interest in the multiple quadratic regression model is established. The expression for this mapping relationship is as follows: ;

[0020] Among them, y n For the nth performance-focused value, x i For the i-th structural parameter, , , and All are fitting coefficients.

[0021] On the other hand, before optimizing the structural parameters based on the mapping relationship, the method further includes:

[0022] The accuracy of the mapping relationship is verified by the average error, maximum error, root mean square error, and coefficient of determination between the actual planetary carrier structural parameters and the corresponding performance characteristics and the mapping relationship.

[0023] When the average error, maximum error, and root mean square error are all lower than a first preset value and the coefficient of determination is higher than a preset value, the accuracy verification is determined to be successful, and the process proceeds to the step of optimizing the structural parameters based on the mapping relationship.

[0024] On the other hand, the accuracy of the mapping relationship is verified based on the average error, maximum error, root mean square error, and coefficient of determination between the actual planetary carrier structural parameters and the corresponding performance characteristics, including:

[0025] Determine the average error between the correspondence between k planetary carrier structural parameters and the performance of interest and the mapping relationship, whereby the expression for the average error is: ;

[0026] Determine the maximum error between the correspondence between k planetary carrier structural parameters and the performance of interest and the mapping relationship, whereby the expression for the maximum error is: ;

[0027] The root mean square error between the correspondence between k planetary carrier structural parameters and the performance of interest and the mapping relationship is determined, and the expression for the root mean square error is: ;

[0028] Determine the coefficients between the correspondence between k planetary carrier structural parameters and the performance of interest and the mapping relationship, wherein the expression for the coefficients is as follows: ;

[0029] Among them, f i This represents the actual performance of interest corresponding to the i-th planetary carrier structural parameter. Let be the performance of interest corresponding to the i-th planetary carrier structural parameter in the mapping relationship, and k be the total number of planetary carrier structural parameters. E represents the average value of the actual performance parameters corresponding to the i-th planetary carrier structural parameter. mean Let E be the average error. max For the maximum error, E RMS R is the root mean square of the error. 2 The coefficient of determination is denoted as .

[0030] On the other hand, parameter optimization of the structural parameters based on the mapping relationship includes:

[0031] With the objective of minimizing the mass of the planetary carrier constructed using the aforementioned structural parameters, the optimized structural parameters are determined under parameter optimization constraints. The optimized structural parameters are X=[x1,x2,…,x…]. i The parameter optimization constraints are as follows: ;

[0032] Where x1 is the first structural parameter, x 1max x is the maximum value of the first structural parameter. 1min x1 is the minimum value of the first structural parameter, x2 is the second structural parameter, and x... 2max x is the maximum value of the first structural parameter. 2min x is the minimum value of the first structural parameter. i Let x be the i-th structural parameter. imax x is the maximum value of the first structural parameter. imin Let θ(X) be the minimum value of the first structural parameter, and θ(X) be the gear shaft torsion angle corresponding to the optimized structural parameter. initial Let X be the torsional angle of the gear shaft in the initial planetary carrier design, and stress(X) be the maximum equivalent stress value corresponding to the optimized structural parameters. initial This represents the maximum equivalent stress value of the initial planetary carrier design.

[0033] On the other hand, after determining the mapping relationship between the structural parameters of the planetary carrier and the performance of interest, the process also includes:

[0034] Determine a sensitivity value between each of the structural parameters and the performance of interest, wherein the sensitivity value is positively correlated with the correlation between the structural parameter and the performance of interest;

[0035] Structural parameters with sensitivity values ​​greater than preset sensitivity values ​​are identified as sensitivity parameters;

[0036] Based on the mapping relationship, the structural parameters are optimized, including:

[0037] The sensitive parameters are optimized based on the mapping relationship.

[0038] On the other hand, determining the sensitivity value between each of the structural parameters and the performance of interest includes:

[0039] For the mapping relationship By taking the derivative, we obtain the derivative mapping relationship. ;

[0040] The main effect of the linear term for each structural parameter is determined based on the derivative mapping relationship, and the expression for the main effect is M. xi =β i dx i dx i =Max(x i )- Min(x i );

[0041] Among them, y n For the nth performance-focused value, x i For the i-th structural parameter, , , and All are fitting coefficients, Max(x) i ) represents the maximum value of the i-th structural parameter, Min(x) i Let M be the minimum value of the i-th structural parameter. xi The main effects of the linear terms for each of the structural parameters;

[0042] Based on the main effects, the sensitivity value of each performance characteristic to each structural parameter is determined, and the expression for the sensitivity value is as follows: N xi The sensitivity of the i-th structural parameter to the performance of interest.

[0043] To address the aforementioned technical problems, the present invention also provides a structural design device for a planetary carrier, comprising:

[0044] Memory, used to store computer programs;

[0045] A processor is used to implement the steps of the above-described planetary carrier structural design method when executing the computer program.

[0046] This invention discloses a structural design method and apparatus for a planetary carrier, relating to the field of planetary carrier technology for gearboxes. The method includes: determining the maximum equivalent stress and maximum gear shaft torsional angle under extreme operating conditions based on historical planetary carrier structures; performing topology optimization with constraints of volume fraction, maximum equivalent stress, and maximum gear shaft torsional angle, and minimizing flexibility as the objective, to obtain a topology-optimized planetary carrier structure; optimizing the structural parameters based on the mapping relationship between the planetary carrier's structural parameters and the performance of interest; and manufacturing the planetary carrier based on the topology-optimized structure and the optimized structural parameters when the equivalent stress and gear shaft torsional angle corresponding to the optimized structural parameters are less than those before optimization. By simultaneously considering stiffness and strength, and adjusting various structural parameters in the planetary carrier under constraints, combining topology optimization and parameter optimization, the resulting planetary carrier has more precise dimensions. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the prior art and embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 A flowchart of a structural design method for a planetary carrier provided by the present invention;

[0049] Figure 2 A schematic diagram of an initial model of a planetary carrier provided by the present invention;

[0050] Figure 3 A schematic diagram of the original structure result cloud map of a planetary carrier provided by the present invention;

[0051] Figure 4 A schematic diagram of a planetary carrier topology optimization design space provided by the present invention;

[0052] Figure 5 A schematic diagram illustrating the topology optimization result of a planetary carrier provided by the present invention;

[0053] Figure 6 A schematic diagram illustrating the performance index prediction accuracy of a planetary carrier surrogate model provided by the present invention;

[0054] Figure 7 A schematic diagram of a final output planetary carrier provided by the present invention;

[0055] Figure 8 This invention provides a schematic diagram illustrating the sensitivity of performance to structural parameters.

[0056] Figure 9 A schematic diagram of the sensitive parameters of a planetary carrier provided by the present invention;

[0057] Figure 10 A schematic diagram of variable structural parameters of a planetary carrier provided by the present invention;

[0058] Figure 11 This is a structural schematic diagram of a planetary carrier structural design device provided by the present invention. Detailed Implementation

[0059] The core of this invention is to provide a structural design method and apparatus for planetary carriers, which simultaneously considers stiffness and strength, and adjusts various structural parameters in the planetary carrier under constraints. By combining topology optimization and parameter optimization, the dimensions of the obtained planetary carrier are more accurate.

[0060] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0061] Figure 1 A flowchart of a structural design method for a planetary carrier provided by the present invention is provided. The structural design method for the planetary carrier includes:

[0062] S11: Determine the maximum equivalent stress and maximum gear shaft torsion angle under extreme conditions based on the historical structure of the planetary carrier. The maximum equivalent stress characterizes the strength of the planetary carrier, and the maximum gear shaft torsion angle characterizes the stiffness of the planetary carrier.

[0063] S12: With volume fraction, maximum equivalent stress value and maximum gear shaft torsion angle as constraints, and minimum flexibility as the optimization objective, topology optimization is performed to obtain the structure of the planetary carrier after topology optimization. Flexibility and stiffness are negatively correlated. The volume fraction is the ratio of the volume of the planetary carrier after topology optimization to the volume of the planetary carrier before topology optimization.

[0064] A finite element analysis model of the initial planetary carrier scheme is established. By applying the ultimate working condition load and boundary conditions of the planetary carrier to the finite element model, the stiffness (torsion angle of the gear shaft under ultimate load) and strength (maximum equivalent stress of the planetary carrier) of the planetary carrier under ultimate working conditions are calculated. If the stiffness and strength are within the range specified by the enterprise standard, the planetary carrier can be guaranteed to meet the usage requirements. The stiffness and strength analysis results of the initial planetary carrier scheme obtained above are used as the upper limit values ​​of the maximum equivalent stress and gear shaft torsion angle of the topology optimization model, that is, the maximum equivalent stress and gear shaft torsion angle constraints are added to the topology optimization model.

[0065] S13: Determine the mapping relationship between the structural parameters of the planetary carrier and the performance of interest, including the mass of the planetary carrier, the equivalent stress value, and the torsional angle of the gear shaft;

[0066] S14: Parameter optimization based on mapping relationship;

[0067] S15: When the equivalent stress value and gear shaft torsion angle corresponding to the optimized structural parameters are less than the equivalent stress value and gear shaft torsion angle before the optimization, manufacture the planetary carrier according to the structure of the topology-optimized planetary carrier and the optimized structural parameters.

[0068] A parametric geometric model of the new planetary carrier design was obtained. The Latin hypersolution method in experimental design was used to sample various structural parameters of the new planetary carrier design, resulting in a geometric model (sampling points) of various combinations of structural parameter values ​​within the design space. The geometric models of each sampling point were used as input for finite element analysis to perform stiffness and strength analysis. Based on the results, the influence of each dimensional parameter on the mass, stiffness, and strength performance of the planetary carrier was studied, and structurally sensitive parameters (parameters with significant impact on planetary carrier performance) were identified. Based on the above sampling points, the relationship between the structurally sensitive parameters of the new planetary carrier design and the stiffness, strength, and mass of the planetary carrier was fitted (i.e., a surrogate model). Sampling points were added until the accuracy of the surrogate model met the requirements, resulting in a high-precision surrogate model. The high-precision surrogate model (which directly and quickly obtains the maximum equivalent stress and torsional angle of the planetary carrier by inputting its structural parameters) was used to optimize the structural parameters of the new planetary carrier design. With the maximum equivalent stress and torsional angle as constraints and the minimum mass as the optimization objective, a lightweight design scheme that meets performance requirements was obtained.

[0069] This invention discloses a structural design method for a planetary carrier, relating to the field of planetary carrier technology for gearboxes. The method includes: determining the maximum equivalent stress and maximum gear shaft torsional angle under extreme operating conditions based on historical planetary carrier structures; performing topology optimization with constraints of volume fraction, maximum equivalent stress, and maximum gear shaft torsional angle, and minimizing flexibility as the objective, to obtain a topology-optimized planetary carrier structure; optimizing the structural parameters based on the mapping relationship between the planetary carrier's structural parameters and the performance of interest; and manufacturing the planetary carrier based on the topology-optimized structure and the optimized structural parameters when the equivalent stress and gear shaft torsional angle corresponding to the optimized structural parameters are less than those before optimization. By simultaneously considering stiffness and strength, and adjusting various structural parameters in the planetary carrier under constraints, combining topology optimization and parameter optimization, the resulting planetary carrier has more precise dimensions.

[0070] Based on the above embodiments:

[0071] Figure 2 This is a schematic diagram of an initial model of a planetary carrier provided by the present invention. Figure 3 This is a schematic diagram of the original structure cloud map of a planetary carrier provided by the present invention. Figure 4 A schematic diagram of a planetary carrier topology optimization design space provided by the present invention;

[0072] Wherein, 1 is the gear shaft, 2 is the local coordinate system, and 3 is the planet carrier;

[0073] In some embodiments, determining the maximum equivalent stress and maximum gear shaft torsional angle under extreme conditions based on the historical planetary carrier structure includes:

[0074] Based on the initial geometric model of the planetary carrier, load boundary conditions are added to the geometric model to establish the maximum equivalent stress value and maximum gear shaft torsional angle of the planetary carrier under extreme working conditions.

[0075] The expression for the maximum equivalent stress value is: , This is the maximum equivalent stress value. , and The expressions for the maximum gear shaft torsional angle, where the first, second, and third principal stresses are respectively the first, second, and third principal stresses, are as follows: θ is the maximum gear shaft torsional angle, Δ max For the maximum displacement along the X-axis of the local coordinate system, Δ minR is the minimum displacement along the X-axis of the local coordinate system, and R is the vertical distance from the center of the gear shaft mounting hole to the planet carrier rotation axis. The local coordinate system is established on the gear shaft, with the origin of the local coordinate system located at the center of each gear shaft. The Z-axis points downward along the gear shaft axis, and the Y-axis points towards the center of the gear shaft along the planet carrier axis. The X-axis forms a right-handed coordinate system with the Y-axis and Z-axis.

[0076] The planetary carrier of a certain type of gearbox is selected as the analysis object. The geometric model of the initial planetary carrier design is used as input, imported into the AnsysWorkbench platform for mesh generation, and load boundary conditions are added to establish a finite element analysis model of the planetary carrier under extreme conditions. The boundary conditions are a fixed constraint on the upper part of the planetary carrier, and gear transmission force and torque applied at the center of the gear shaft. Based on the calculation results, the mass of the planetary carrier, the maximum equivalent stress, and the gear shaft torsional angle are extracted as the performance parameters of interest. The mass of the planetary carrier is obtained according to m = ρ × v, where m is the mass of the planetary carrier, ρ is the density of the planetary carrier material, and v is the volume of the planetary carrier. The finite element model of the planetary carrier includes the main body of the planetary carrier and the gear shaft. The gear shaft and the planetary carrier are connected by an interference contact. A local coordinate system is established on the gear shaft, with the origin located at the center of each planetary gear shaft. The Z-axis points downwards along the gear shaft axis; the Y-axis points towards the center of the gear shaft along the planetary carrier axis; and the X-axis forms a right-handed coordinate system with the Y and Z axes.

[0077] Figure 5 A schematic diagram illustrating the topology optimization result of a planetary carrier provided by the present invention;

[0078] In some embodiments, topology optimization is performed with constraints of volume fraction, maximum equivalent stress value, and maximum gear shaft torsional angle, and with minimum compliance as the optimization objective, to obtain the topology-optimized planetary carrier structure, including:

[0079] Establish the topology optimization design region for the planet carrier and remove material from the gear region of the planet carrier;

[0080] Add axisymmetric and radial draft manufacturing constraints to the topology optimization design region;

[0081] With volume fraction, maximum equivalent stress value and maximum gear shaft torsional angle as constraints, and minimum compliance as the optimization objective, topology optimization of the design region is performed.

[0082] Among them, the maximum equivalent stress value is the maximum equivalent stress value after constraint characterization optimization which is less than the maximum equivalent stress value calculated by the initial scheme, and the maximum gear shaft torsion angle is the maximum gear shaft torsion angle after constraint characterization optimization which is less than the maximum gear shaft torsion angle calculated by the initial scheme.

[0083] Based on the structural design and functional requirements of the planetary carrier, and considering the gear installation on the gear shaft, material needs to be removed from the corresponding area. Simultaneously, based on the number of gear shafts to be installed, the required axial array of material distribution in the design area is determined, establishing a topology optimization design area. Considering the gear shafts need to install gears, material was removed from the gear installation area in the middle of the planetary carrier. According to the planetary carrier structural design requirements, axisymmetric and radial draft manufacturing constraints were added to the topology optimization design area. Topology optimization was performed using volume fraction, maximum equivalent stress value, and gear shaft torsion angle as optimization constraints, with minimum compliance as the optimization objective. Here, volume fraction, maximum equivalent stress value, and gear shaft torsion angle are three constraints. The volume fraction constraint is set based on the remaining volume of the structure (topology optimization design area) after weight reduction. The maximum equivalent stress constraint means that the optimized maximum equivalent stress value is less than the maximum equivalent stress value calculated in the initial scheme. The torsion angle is similar to the maximum equivalent stress value; the optimized value is less than the torsion angle calculated in the initial scheme.

[0084] The structural topology optimization results should clearly show the force flow transmission path in the planetary carrier structure, and the structural interpretation should be carried out with reference to the topology optimization results as much as possible. The interpretation of the topology optimization results should be carried out without increasing the difficulty of the existing process. The manufacturing process characteristics of the planetary carrier should be fully considered, and the wall thickness should not have large changes in thickness dimension, that is, the thickness change should be gradual. The interpretation of the topology optimization results should take into account the structural design of auxiliary functions.

[0085] In some embodiments, determining the mapping relationship between the structural parameters of the planetary carrier and the performance of interest includes:

[0086] Based on the selection points determined by the Latin hypersolution method, a mapping relationship between the fitted structural parameters and the performance of interest in the multiple quadratic regression model is established. The expression for this mapping relationship is as follows: ;

[0087] Among them, y n For the nth performance-focused value, x i For the i-th structural parameter, , , and All are fitting coefficients.

[0088] A co-simulation platform combining SolidWorks and Ansys Workbench was built to automate the creation of a parametric geometric model in SolidWorks and the construction of a planetary carrier finite element model in Ansys Workbench for simulation analysis and extraction of performance of interest. Based on Design of Experiments (DOE), the contribution of each structural parameter of the planetary carrier to the performance of interest was analyzed, and structurally sensitive parameters were identified. When drawing the 3D model of the planetary carrier, many dimensional parameters need to be provided, such as fillet radius, thickness, and length, which are the structural parameters.

[0089] It should also be noted that the selection of fitting coefficients should be set according to the actual data, and this application does not impose any restrictions here.

[0090] The experimental design uses all variable structural parameters from the parametric model of the new planetary carrier design as input, and extracts the mass, maximum equivalent stress, and gear shaft torsional angle performance of the planetary carrier as output. The method for determining sampling points in the experimental design is the Latin hypercube method, which works by determining the coordinate intervals in each dimension of an n-dimensional space based on the number of inputs n. , Let k∈[1,n] be uniformly divided into m intervals, each interval denoted as . , i∈[1,m].

[0091] In some embodiments, before performing parameter optimization on the structural parameters based on the mapping relationship, the method further includes:

[0092] The accuracy of the mapping relationship is verified based on the average error, maximum error, root mean square error, and coefficient of determination between the actual planetary carrier structural parameters and the corresponding and mapping relationships of the performance of interest.

[0093] When the average error, maximum error, and root mean square error are all lower than the first preset value and the coefficient of determination is higher than the preset value, the accuracy verification is passed, and the process proceeds to the step of optimizing the structural parameters based on the mapping relationship.

[0094] We introduce the neural network RBF method to construct a high-precision proxy model of the mapping relationship between the planetary carrier's sensitive parameters and the performance of concern. We use the gradient optimization algorithm NLPQLP to perform lightweight design of the planetary carrier and verify the lightweight design through simulation.

[0095] Figure 6 A schematic diagram illustrating the performance index prediction accuracy of a planetary carrier surrogate model provided by the present invention;

[0096] In some embodiments, the accuracy of the mapping relationship is verified based on the average error, maximum error, root mean square error, and coefficient of determination between the actual planetary carrier structural parameters and the correspondence and mapping relationship of the performance of interest, including:

[0097] The average error between the correspondence and mapping relationship between k planetary carrier structural parameters and the performance of interest is determined. The expression for the average error is as follows: ;

[0098] Determine the maximum error between the correspondence and mapping relationship between k planetary carrier structural parameters and the performance of interest. The expression for the maximum error is: ;

[0099] The root mean square error between the correspondence and mapping relationship between k planetary carrier structural parameters and the performance of interest is determined. The expression for the root mean square error is as follows: ;

[0100] Determine the coefficients of determination between the correspondence and mapping relationship between k planetary carrier structural parameters and the performance of interest. The expression for the coefficients of determination is as follows: ;

[0101] Among them, f i This represents the actual performance of interest corresponding to the i-th planetary carrier structural parameter. Let represent the performance of interest corresponding to the i-th planetary carrier structural parameter in the mapping relationship, and k be the total number of planetary carrier structural parameters. E represents the average value of the actual performance parameters corresponding to the i-th planetary carrier structural parameter. mean E represents the average error. max For the maximum error, E RMS R is the root mean square error. 2 To determine the coefficients.

[0102] Among them, the accuracy index E mean E max E RMS A smaller value indicates higher accuracy of the surrogate model, while the accuracy index R... 2 The closer the value is to 1, the higher the accuracy of the surrogate model. A high-accuracy surrogate model must meet the following condition: E mean ≤0.15, E max ≤0.15, E RMS ≤0.15, R 2 ≥0.9.

[0103] Figure 7 A schematic diagram of a final output planetary carrier provided by the present invention;

[0104] In some embodiments, parameter optimization of structural parameters based on mapping relationships includes:

[0105] With the objective of minimizing the mass of the planetary carrier composed of structural parameters, the optimized structural parameters are determined under parameter optimization constraints. The optimized structural parameters are X=[x1,x2,…,x…]. i The parameter optimization constraints are: ;

[0106] Where x1 is the first structural parameter, x 1max x is the maximum value of the first structural parameter. 1min x1 is the minimum value of the first structure parameter, x2 is the second structure parameter, and x... 2max x is the maximum value of the first structural parameter. 2minx is the minimum value of the first structure parameter. i Let x be the i-th structural parameter. imax x is the maximum value of the first structural parameter. imin Let θ(X) be the minimum value of the first structural parameter, and θ(X) be the gear shaft torsion angle corresponding to the optimized structural parameters. initial Let X be the torsional angle of the gear shaft in the initial planetary carrier design, and stress(X) be the maximum equivalent stress value corresponding to the optimized structural parameters. initial This represents the maximum equivalent stress value of the initial planetary carrier design.

[0107] Find a combination of structural parameters that forms X = [x1, x2, ..., x]. i When the mass reaches its minimum value, and the gear shaft torsional angle and maximum equivalent stress corresponding to this parameter combination are both less than those of the initial scheme, the parameter optimization is confirmed to be successful. Further, it needs to be verified through simulation using Ansys Workbench software before it can be used as the subsequent planetary carrier dimensions.

[0108] Figure 8 This is a schematic diagram illustrating the sensitivity of performance to structural parameters, as provided by the present invention. Figure 9 This is a schematic diagram of the sensitive parameters of a planetary carrier provided by the present invention. Figure 10 A schematic diagram of variable structural parameters of a planetary carrier provided by the present invention;

[0109] Wherein, 4 is the radius of the support column, 5 is the distance the inner wall moves outward, 6 is the axis of rotation, 7 is the rotation angle 1, 8 is the rotation angle 2, 9 is the distance the concave wall moves outward, 10 is the thickness of the upper wall, 11 is the thickness of the lower wall, 12 is the radius of the concave corner, and 13 is the radius of the wall corner.

[0110] In some embodiments, after determining the mapping relationship between the structural parameters of the planetary carrier and the performance of interest, the method further includes:

[0111] Determine the sensitivity value between each structural parameter and the performance of interest. The sensitivity value is positively correlated with the correlation between the structural parameter and the performance of interest.

[0112] Structural parameters with sensitivity values ​​greater than preset sensitivity values ​​are identified as sensitivity parameters;

[0113] Parameter optimization based on mapping relationships is performed on structural parameters, including:

[0114] Parameter optimization is performed on sensitive parameters based on mapping relationships.

[0115] There are dozens or even hundreds of parameters in the planetary carrier structure. We select the parameters that have a significant impact on performance and optimize them, which is called identifying sensitive parameters.

[0116] In some embodiments, determining the sensitivity value between each structural parameter and the performance of interest includes:

[0117] For mapping relationship By taking the derivative, we obtain the derivative mapping relationship. ;

[0118] The main effect of the linear term for each structural parameter is determined based on the derivative mapping relationship. The expression for the main effect is M. xi =β i dx i dx i =Max(x i )- Min(x i );

[0119] Among them, y n For the nth performance-focused value, x i For the i-th structural parameter, , , and All are fitting coefficients, Max(x) i ) represents the maximum value of the i-th structural parameter, Min(x) i Let M be the minimum value of the i-th structural parameter. xi The main effects of the linear terms for each structural parameter;

[0120] The sensitivity value of each performance parameter to each structural parameter is determined based on the main effect. The expression for the sensitivity value is as follows: N xi Let be the sensitivity of the i-th structural parameter to the performance we are concerned with.

[0121] M xi The absolute value of is greater than 5, which indicates that the parameter is sensitive to this performance. When the value of N is greater than 5, the parameter is sensitive to the performance of the parameter. xi When the absolute values ​​are all less than 5, they are non-sensitive parameters. The thickness of the upper and lower walls of the planetary carrier, the radius of the corner of the support column, the moving distance of the inner wall of the support column, the moving distance of the concave wall outward, and the rotation angle of the support column wall are sensitive parameters.

[0122] Figure 11 This is a schematic diagram of a planetary carrier structural design device provided by the present invention. The planetary carrier structural design device includes:

[0123] Memory 21 is used to store computer programs;

[0124] The processor 22 is used to implement the steps of the above-described planetary carrier structural design method when executing a computer program.

[0125] The description of the structural design device for the planetary carrier provided in this application is given in the above embodiments and will not be repeated here.

[0126] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0127] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0128] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0129] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A structural design method for a planetary carrier, characterized in that, include: The maximum equivalent stress and maximum gear shaft torsion angle under extreme operating conditions are determined based on the historical structure of the planetary carrier. The maximum equivalent stress characterizes the strength of the planetary carrier, and the maximum gear shaft torsion angle characterizes the stiffness of the planetary carrier. With volume fraction, maximum equivalent stress value, and maximum gear shaft torsional angle as constraints, topology optimization is performed with minimum flexibility as the optimization objective to obtain the structure of the planetary carrier after topology optimization. The flexibility is negatively correlated with the stiffness. The volume fraction is the ratio of the volume of the planetary carrier after topology optimization to the volume of the planetary carrier before topology optimization. Determine the mapping relationship between the structural parameters of the planetary carrier and the performance of interest, including the mass of the planetary carrier, the equivalent stress value, and the torsional angle of the gear shaft; Based on the mapping relationship, the structural parameters are optimized; When the equivalent stress value and gear shaft torsion angle corresponding to the optimized structural parameters are less than the equivalent stress value and gear shaft torsion angle before parameter optimization, the planet carrier is manufactured according to the topology-optimized structure of the planet carrier and the optimized structural parameters. Determining the mapping relationship between the structural parameters of the planetary carrier and the performance of interest includes: Based on the selection points determined by the Latin hypersolution method, a mapping relationship between the fitting structural parameters and the performance of interest in the multiple quadratic regression model is established. The expression for this mapping relationship is as follows: ; Among them, y n For the nth performance-focused value, x i For the i-th structural parameter, , , and All are fitting coefficients; Based on the mapping relationship, the structural parameters are optimized, including: With the objective of minimizing the mass of the planetary carrier constructed using the aforementioned structural parameters, the optimized structural parameters are determined under parameter optimization constraints. The optimized structural parameters are X=[x1,x2,…,x…]. i The parameter optimization constraints are as follows: ; Where x1 is the first structural parameter, x 1max x is the maximum value of the first structural parameter. 1min x1 is the minimum value of the first structural parameter, x2 is the second structural parameter, and x... 2max x is the maximum value of the first structural parameter. 2min x is the minimum value of the first structural parameter. i Let x be the i-th structural parameter. imax x is the maximum value of the first structural parameter. imin Let θ(X) be the minimum value of the first structural parameter, and θ(X) be the gear shaft torsion angle corresponding to the optimized structural parameter. initial Let X be the torsional angle of the gear shaft in the initial planetary carrier design, and stress(X) be the maximum equivalent stress value corresponding to the optimized structural parameters. initial This represents the maximum equivalent stress value of the initial planetary carrier design.

2. The structural design method for the planetary carrier as described in claim 1, characterized in that, The maximum equivalent stress and maximum gear shaft torsional angle under extreme conditions are determined based on the historical structure of the planetary carrier, including: Based on the initial geometric model of the planetary carrier, load boundary conditions are added to the geometric model to establish the maximum equivalent stress value and maximum gear shaft torsion angle of the planetary carrier under extreme working conditions. The expression for the maximum equivalent stress value is as follows: , This is the maximum equivalent stress value. , and The first, second, and third principal stresses are respectively, and the expression for the maximum gear shaft torsional angle is: θ is the maximum gear shaft torsional angle. max This represents the maximum displacement along the X-axis in the local coordinate system. min R is the minimum displacement along the X-axis of the local coordinate system, and R is the vertical distance from the center of the gear shaft mounting hole to the planet carrier rotation axis. The local coordinate system is established on the gear shaft, and the origin of the local coordinate system is located at the center of each gear shaft. The Z-axis points downward along the gear shaft axis, and the Y-axis points towards the center of the gear shaft along the planet carrier axis. The X-axis forms a right-handed coordinate system with the Y-axis and Z-axis.

3. The structural design method for the planetary carrier as described in claim 1, characterized in that, Using volume fraction, maximum equivalent stress value, and maximum gear shaft torsional angle as constraints, and minimizing compliance as the optimization objective, topology optimization is performed to obtain the topology-optimized structure of the planetary carrier, including: Establish the topology optimization design region of the planet carrier, and remove material from the gear region of the planet carrier; Add axisymmetric and radial draft manufacturing constraints to the topology optimization design region; With volume fraction, maximum equivalent stress value and maximum gear shaft torsional angle as constraints, and minimum compliance as the optimization objective, the topology optimization design region is optimized. Wherein, the maximum equivalent stress value is the maximum equivalent stress value after constraint characterization optimization which is less than the maximum equivalent stress value calculated in the initial scheme, and the maximum gear shaft torsion angle is the maximum gear shaft torsion angle after constraint characterization optimization which is less than the maximum gear shaft torsion angle calculated in the initial scheme.

4. The structural design method for the planetary carrier as described in claim 1, characterized in that, Before optimizing the structural parameters based on the mapping relationship, the method further includes: The accuracy of the mapping relationship is verified by the average error, maximum error, root mean square error, and coefficient of determination between the actual planetary carrier structural parameters and the corresponding performance characteristics and the mapping relationship. When the average error, maximum error, and root mean square error are all lower than a first preset value and the coefficient of determination is higher than a preset value, the accuracy verification is determined to be successful, and the process proceeds to the step of optimizing the structural parameters based on the mapping relationship.

5. The structural design method for the planetary carrier as described in claim 4, characterized in that, The accuracy of the mapping relationship is verified based on the average error, maximum error, root mean square error, and coefficient of determination between the actual planetary carrier structural parameters and the performance parameters of interest and the mapping relationship. This includes: Determine the average error between the correspondence between k planetary carrier structural parameters and the performance of interest and the mapping relationship, whereby the expression for the average error is: ; Determine the maximum error between the correspondence between k planetary carrier structural parameters and the performance of interest and the mapping relationship, whereby the expression for the maximum error is: ; The root mean square error between the correspondence between k planetary carrier structural parameters and the performance of interest and the mapping relationship is determined, and the expression for the root mean square error is: ; Determine the coefficients between the correspondence between k planetary carrier structural parameters and the performance of interest and the mapping relationship, wherein the expression for the coefficients is as follows: ; Among them, f i This represents the actual performance of interest corresponding to the i-th planetary carrier structural parameter. Let be the performance of interest corresponding to the i-th planetary carrier structural parameter in the mapping relationship, and k be the total number of planetary carrier structural parameters. E represents the average value of the actual performance parameters corresponding to the i-th planetary carrier structural parameter. mean E is the average error. max For the maximum error, E RMS R is the root mean square of the error. 2 The coefficient of determination is denoted as .

6. The structural design method for a planetary carrier as described in any one of claims 1 to 5, characterized in that, After determining the mapping relationship between the structural parameters of the planetary carrier and the performance of interest, the process also includes: Determine a sensitivity value between each of the structural parameters and the performance of interest, wherein the sensitivity value is positively correlated with the correlation between the structural parameter and the performance of interest; Structural parameters with sensitivity values ​​greater than preset sensitivity values ​​are identified as sensitivity parameters; Based on the mapping relationship, the structural parameters are optimized, including: The sensitive parameters are optimized based on the mapping relationship.

7. The structural design method for the planetary carrier as described in claim 6, characterized in that, Determining the sensitivity value between each of the structural parameters and the performance of interest includes: For the mapping relationship By taking the derivative, we obtain the derivative mapping relationship. ; The main effect of the linear term for each structural parameter is determined based on the derivative mapping relationship, and the expression for the main effect is M. xi =β i dx i dx i =Max(x i )- Min(x i ); Among them, y n For the nth performance-focused value, x i For the i-th structural parameter, , , and All are fitting coefficients, Max(x) i ) represents the maximum value of the i-th structural parameter, Min(x) i Let M be the minimum value of the i-th structural parameter. xi The main effects of the linear terms for each of the structural parameters; Based on the main effects, the sensitivity value of each performance characteristic to each structural parameter is determined, and the expression for the sensitivity value is as follows: N xi The sensitivity of the i-th structural parameter to the performance of interest.

8. A structural design device for a planetary carrier, characterized in that, include: Memory, used to store computer programs; A processor, configured to execute the computer program to implement the steps of the structural design method for the planetary carrier as described in any one of claims 1 to 7.

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