Structural design method and device for planet carrier

Abstract

The invention discloses a structural design method and device for a planet carrier, and relates to the technical field of gear box planet carriers. The structural design method comprises the steps that the maximum equivalent stress value and the maximum gear shaft torsion angle under the limiting working condition are determined according to the historical structure of the planet carrier; carrying out topological optimization by taking the volume fraction, the maximum equivalent stress value and the maximum gear shaft torsion angle as constraints and taking the minimum flexibility as a target to obtain the structure of the planet carrier after topological optimization; performing parameter optimization on the structure parameters based on the mapping relation between the structure parameters of the planet carrier and the concerned performance; and when the equivalent stress value and the gear shaft torsion angle corresponding to the structural parameters after parameter optimization are smaller than the equivalent stress value and the gear shaft torsion angle before parameter optimization, the planet carrier is manufactured according to the structure of the planet carrier after topological optimization and the structural parameters after parameter optimization. According to the method, the rigidity and the strength are considered at the same time, all structural parameters in the planet carrier are adjusted under constraints, topological optimization and parameter optimization are combined, and the obtained size of the planet carrier is more accurate.

Description

Technical Field

[0001] The present invention relates to the technical field of planetary carriers of gearboxes, and particularly to a structural design method and device for a planetary carrier. Background Art

[0002] To meet the growing market demand and the accelerating product iteration speed, the strategy of rapid structural optimization has become an inevitable choice. The commonly used lightweight design strategy in industrial design is that designers adjust individual structural parameters of the planetary carrier according to past design experience, and then perform finite element checking on the adjusted design scheme. If the stiffness and strength performance requirements are not met, the structural parameters need to be modified again until the stiffness and strength performance requirements are met before the structural parameters can be used as the dimensions of the planetary carrier. Therefore, in related technologies, it often takes multiple modification iterations to obtain a better scheme, resulting in low design efficiency. Summary of the Invention

[0003] The purpose of the present invention is to provide a structural design method and device for a planetary carrier, which simultaneously consider stiffness and strength, adjust various structural parameters in the planetary carrier under constraints, combine topology optimization and parameter optimization, and obtain more accurate dimensions of the planetary carrier.

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

[0005] Determine the maximum equivalent stress value and the maximum gear shaft torsional angle under extreme working conditions according to the structure of the historical planetary carrier, where the maximum equivalent stress value characterizes the strength of the planetary carrier, and the maximum gear shaft torsional angle characterizes the stiffness of the planetary carrier;

[0006] Perform topology optimization with the volume fraction, the maximum equivalent stress value, and the maximum gear shaft torsional angle as constraints and the minimum compliance as the optimization objective to obtain the structure of the planetary carrier after topology optimization. The compliance is negatively correlated with the stiffness, and 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 concerned performance, where the concerned performance includes the mass, equivalent stress value, and gear shaft torsional angle of the planetary carrier;

[0008] Perform parameter optimization on the structural parameters based on the mapping relationship;

[0009] When the equivalent stress value and the gear shaft torsional angle corresponding to the structural parameters after parameter optimization are smaller than those before parameter optimization, manufacture the planetary carrier according to the structure of the planetary carrier after topology optimization and the structural parameters after parameter optimization.

[0010] On the other hand, determine the maximum equivalent stress value and the maximum gear shaft torsional angle under extreme working conditions according to the structure of the historical planet carrier, including:

[0011] Based on the geometric model of the initial scheme of the planet carrier, add load boundary conditions to the geometric model to establish the maximum equivalent stress value and the maximum gear shaft torsional angle of the planet carrier under extreme working conditions;

[0012] Among them, the expression of the maximum equivalent stress value is , is the maximum equivalent stress value, , and are the first, second and third principal stresses respectively. The expression of the maximum gear shaft torsional angle is , θ is the maximum gear shaft torsional angle, △ max is the maximum displacement in the X-axis direction of the local coordinate system, △ min is the minimum displacement in the X-axis direction of the local coordinate system, R is the vertical distance from the center of the gear shaft installation hole to the rotation axis of the planet carrier. The local coordinate system is established on the gear shaft, the origin of the local coordinate system is located at the center of each gear shaft, the Z-axis is along the axial direction of the gear shaft downward, the Y-axis points to the center of the gear shaft along the axis of the planet carrier, and the X-axis forms a right-hand coordinate system with the Y-axis and the Z-axis.

[0013] On the other hand, taking the volume fraction, the maximum equivalent stress value and the maximum gear shaft torsional angle as constraints, and taking the minimum compliance as the optimization objective, perform topology optimization to obtain the structure of the planet carrier after topology optimization, including:

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

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

[0016] Taking the volume fraction, the maximum equivalent stress value and the maximum gear shaft torsional angle as constraints, perform topology optimization on the topology optimization design area with the minimum compliance as the optimization objective greater than the above;

[0017] Among them, the constraint of the maximum equivalent stress value means that the maximum equivalent stress value after optimization is less than the maximum equivalent stress value calculated by the initial scheme, and the constraint of the maximum gear shaft torsional angle means that the maximum gear shaft torsional angle after optimization is less than the maximum gear shaft torsional angle calculated by the initial scheme.

[0018] On the other hand, determine the mapping relationship between the structural parameters of the planet carrier and the concerned performance, including:

[0019] Adopt points determined by the Latin hypercube method to establish a multiple quadratic regression model to fit the mapping relationship between structural parameters and concerned performances. The expression of the mapping relationship is ;

[0020] where y n is the nth concerned performance, and x i is the ith structural parameter, , , and are all fitting coefficients.

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

[0022] Verify the accuracy of the mapping relationship based on the average error, maximum error, root mean square error and determination coefficient between the corresponding relationship of the actual planetary carrier structural parameters and the concerned performances and the mapping relationship;

[0023] When the average error, maximum error and root mean square error are all lower than the first preset value and the determination coefficient is higher than the preset value, it is determined that the accuracy verification passes, and enter the step of optimizing the structural parameters based on the mapping relationship.

[0024] On the other hand, verifying the accuracy of the mapping relationship based on the average error, maximum error, root mean square error and determination coefficient between the corresponding relationship of the actual planetary carrier structural parameters and the concerned performances and the mapping relationship includes:

[0025] Determine the average error between the corresponding relationship of k planetary carrier structural parameters and the concerned performances and the mapping relationship. The expression of the average error is ;

[0026] Determine the maximum error between the corresponding relationship of k planetary carrier structural parameters and the concerned performances and the mapping relationship. The expression of the maximum error is ;

[0027] Determine the root mean square error between the corresponding relationship of k planetary carrier structural parameters and the concerned performances and the mapping relationship. The expression of the root mean square error is ;

[0028] Determine the determination coefficient between the corresponding relationship of k planetary carrier structural parameters and the concerned performances and the mapping relationship. The expression of the determination coefficient is ;

[0029] where f i is the actual concerned performance corresponding to the ith planetary carrier structural parameter, is the concerned performance corresponding to the i-th planetary carrier structure parameter in the mapping relationship, k is the total number of the planetary carrier structure parameters, is the average value of the actual concerned performance corresponding to the i-th planetary carrier structure parameter, E mean is the average error, E max is the maximum error, E RMS is the root mean square error, R 2 is the coefficient of determination.

[0030] On the other hand, parameter optimization is performed on the structure parameters based on the mapping relationship, including:

[0031] Taking the minimum mass of the planetary carrier formed by the structure parameters as the goal, the structure parameters after parameter optimization are determined under parameter optimization constraints. The structure parameters after parameter optimization are X = [x 1 , x 2 , …, x i , and the parameter optimization constraints are ;

[0032] wherein, x 1 is the first structure parameter, x 1max is the maximum value of the first structure parameter, x 1min is the minimum value of the first structure parameter, x 2 is the second structure parameter, x 2max is the maximum value of the first structure parameter, x 2min is the minimum value of the first structure parameter, x i is the i-th structure parameter, x imax is the maximum value of the first structure parameter, x imin is the minimum value of the first structure parameter, θ(X) is the torsional angle of the gear shaft corresponding to the structure parameters after parameter optimization, θ initial is the torsional angle of the gear shaft of the initial plan of the planetary carrier, stress(X) is the maximum equivalent stress value corresponding to the structure parameters after parameter optimization, stress initial is the maximum equivalent stress value of the initial plan of the planetary carrier.

[0033] On the other hand, after determining the mapping relationship between the structure parameters of the planetary carrier and the concerned performance, it further includes:

[0034] Determining the sensitivity value between each of the structure parameters and the concerned performance, and the sensitivity value is positively correlated with the correlation between the structure parameters and the concerned performance;

[0035] Determining the structure parameters with sensitivity values greater than the preset sensitivity value as sensitive parameters;

[0036] Performing parameter optimization on the structural parameters based on the mapping relationship, including:

[0037] Performing parameter optimization on the sensitive parameters based on the mapping relationship.

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

[0039] Taking the derivative of the mapping relationship to obtain the derivative mapping relationship ;

[0040] Determining the main effect of the linear term of each of the structural parameters according to the derivative mapping relationship, and the expression of the main effect is M xi =β i dx i , dx i =Max(x i ) - Min(x i );

[0041] where y n is the nth concerned performance, x i is the ith structural parameter, , , and are all fitting coefficients, Max(x i ) is the maximum value of the ith structural parameter, Min(x i ) is the minimum value of the ith structural parameter, and M xi is the main effect of the linear term of each of the structural parameters;

[0042] Determining the sensitivity value of each concerned performance to each structural parameter according to the main effect, and the expression of the sensitivity value is , and N xi is the sensitivity of the ith structural parameter to the concerned performance.

[0043] To solve the above technical problems, the present invention also provides a structural design device for a planet carrier, including:

[0044] A memory for storing a computer program;

[0045] A processor for implementing the steps of the above structural design method of the planet carrier when executing the computer program.

[0046] The present invention discloses a structural design method and device for a planet carrier, relating to the technical field of the planet carrier of a gearbox, including: determining the maximum equivalent stress value and the maximum torsional angle of the gear shaft under extreme working conditions according to the structure of the historical planet carrier; performing topology optimization with the volume fraction, the maximum equivalent stress value, and the maximum torsional angle of the gear shaft as constraints and the minimum compliance as the objective to obtain the structure of the planet carrier after topology optimization; performing parameter optimization on the structural parameters based on the mapping relationship between the structural parameters of the planet carrier and the concerned performance; when the equivalent stress value and the torsional angle of the gear shaft corresponding to the structural parameters after parameter optimization are smaller than those before parameter optimization, manufacturing the planet carrier according to the structure of the planet carrier after topology optimization and the structural parameters after parameter optimization. Both stiffness and strength are considered, and each structural parameter in the planet carrier is adjusted under constraints. By combining topology optimization and parameter optimization, the size of the obtained planet carrier is more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the prior art and the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0048] Figure 1 It is a flowchart of a structural design method for a planet carrier provided by the present invention;

[0049] Figure 2 It is a schematic diagram of an initial scheme model of a planet carrier provided by the present invention;

[0050] Figure 3 It is a schematic diagram of a result nephogram of the original structure of a planet carrier provided by the present invention;

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

[0052] Figure 5 It is a schematic diagram of a topology optimization result of a planet carrier provided by the present invention;

[0053] Figure 6 It is a schematic diagram of the prediction accuracy of the performance index of a surrogate model of a planet carrier provided by the present invention;

[0054] Figure 7 It is a schematic diagram of a finally output planet carrier provided by the present invention;

[0055] Figure 8 It is a schematic diagram of the sensitivity of the concerned performance to the structural parameters of a planet carrier provided by the present invention;

[0056] Figure 9 Schematic diagram of sensitive parameters of a planet carrier provided by the present invention;

[0057] Figure 10 Schematic diagram of variable structural parameters of a planet carrier provided by the present invention;

[0058] Figure 11 Schematic structural diagram of a structural design device of a planet carrier provided by the present invention. Specific embodiments

[0059] The core of the present invention is to provide a structural design method and device for a planet carrier, which simultaneously consider stiffness and strength, and adjust various structural parameters in the planet carrier under constraints, combining topology optimization and parameter optimization, so that the size of the obtained planet carrier is more accurate.

[0060] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0061] Figure 1 Flowchart of a structural design method of a planet carrier provided by the present invention. The structural design method of the planet carrier includes:

[0062] S11: Determine the maximum equivalent stress value and the maximum gear shaft torsion angle under extreme working conditions according to the structure of the historical planet carrier. The maximum equivalent stress value characterizes the strength of the planet carrier, and the maximum gear shaft torsion angle characterizes the stiffness of the planet carrier;

[0063] S12: Perform topology optimization with the volume fraction, the maximum equivalent stress value, and the maximum gear shaft torsion angle as constraints and the minimum compliance as the optimization objective to obtain the structure of the planet carrier after topology optimization. The compliance is negatively correlated with the stiffness, and the volume fraction is the ratio of the volume of the planet carrier after topology optimization to the volume of the planet carrier before topology optimization;

[0064] Establish a finite element analysis model for the initial planetary carrier design. By applying the extreme working condition loads and boundaries of the planetary carrier to the finite element model, calculate the stiffness (the torsional angle of the gear shaft under extreme loads) and strength (the maximum equivalent stress of the planetary carrier) of the planetary carrier under extreme working conditions. If the stiffness and strength are within the range specified by the enterprise standard, it can ensure that the planetary carrier meets the usage requirements; use the stiffness and strength analysis results of the initial planetary carrier design obtained above as the upper limit values of the maximum equivalent stress and the torsional angle of the gear shaft in the topology optimization model, and add constraints on the maximum equivalent stress and the torsional angle to the topology optimization model.

[0065] S13: Determine the mapping relationship between the structural parameters of the planetary carrier and the concerned performance. The concerned performance includes the mass of the planetary carrier, the equivalent stress value, and the torsional angle of the gear shaft.

[0066] S14: Optimize the structural parameters based on the mapping relationship.

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

[0068] Obtain the parametric geometric model of the new version of the planetary carrier design; use the Latin hypercube method in experimental design to sample each structural parameter of the new version of the planetary carrier design to obtain geometric models (sampling points) of various combinations of structural parameter values within the design space of the planetary carrier; use each sampling point geometric model as the input for finite element analysis for stiffness and strength analysis, and then study the influence of each dimension parameter on the mass, stiffness, and strength performance of the planetary carrier based on the above results, and identify the structure-sensitive parameters (parameters that have a great impact on the performance of the planetary carrier); on the basis of the above sampling points, fit the relationship between the structure-sensitive parameters of the new version of the planetary carrier design and the stiffness, strength, and mass of the planetary carrier (i.e., the surrogate model), and supplement the sampling points until the accuracy of the surrogate model meets the requirements to obtain a high-precision surrogate model; use the high-precision surrogate model (inputting the structural parameters of the planetary carrier can directly and quickly obtain the maximum equivalent stress and torsional angle of the planetary carrier) to optimize the structural parameters of the new version of the planetary carrier design, with the maximum equivalent stress and torsional angle as the constraint conditions and the minimum mass as the optimization goal to obtain a lightweight design plan that meets the performance requirements.

[0069] The present invention discloses a structural design method for a planet carrier, which relates to the technical field of the planet carrier of a gearbox and includes: determining the maximum equivalent stress value and the maximum torsional angle of the gear shaft under extreme working conditions according to the structure of the historical planet carrier; performing topology optimization with the volume fraction, the maximum equivalent stress value, and the maximum torsional angle of the gear shaft as constraints and the minimum compliance as the objective to obtain the structure of the planet carrier after topology optimization; performing parameter optimization on the structural parameters based on the mapping relationship between the structural parameters of the planet carrier and the concerned performance; when the equivalent stress value and the torsional angle of the gear shaft corresponding to the structural parameters after parameter optimization are smaller than those before parameter optimization, manufacturing the planet carrier according to the structure of the planet carrier after topology optimization and the structural parameters after parameter optimization. Both stiffness and strength are considered, and each structural parameter in the planet carrier is adjusted under constraints, combining topology optimization and parameter optimization, so that the size of the obtained planet carrier is more accurate.

[0070] Based on the above embodiments:

[0071] Figure 2 It is a schematic diagram of an initial scheme model of a planet carrier provided by the present invention. Figure 3 It is a schematic diagram of a result nephogram of the original structure of a planet carrier provided by the present invention. Figure 4 It is a schematic diagram of the topology optimization design space of a planet carrier provided by the present invention.

[0072] Among them, 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 value and the maximum torsional angle of the gear shaft under extreme working conditions according to the structure of the historical planet carrier includes:

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

[0075] Among them, the expression of the maximum equivalent stress value is , is the maximum equivalent stress value, , and are the first, second, and third principal stresses respectively, and the expression of the maximum torsional angle of the gear shaft is , θ is the maximum torsional angle of the gear shaft, △ max is the maximum displacement in the X-axis direction of the local coordinate system, △ minis the minimum displacement in the X - axis direction of the local coordinate system, R is the vertical distance from the center of the gear shaft mounting hole to the rotating axis of the planet carrier. The local coordinate system is established on the gear shaft, the origin of the local coordinate system is located at the center of each gear shaft, the Z - axis points downward along the axial direction of the gear shaft, the Y - axis points towards the center of the gear shaft along the axis of the planet carrier, and the X - axis forms a right - hand coordinate system with the Y - axis and the Z - axis.

[0076] Select the planet carrier of a certain type of gearbox as the analysis object. Take the geometric model of the initial scheme of the planet carrier as the input, import it into the Ansys Workbench platform for mesh generation and add load boundary conditions to establish a finite - element analysis model of the planet carrier under extreme conditions. The boundary conditions are that the upper part of the planet carrier is fixed and constrained, and gear transmission forces and torques are applied at the center of the gear shaft. According to the calculation results, extract the mass of the planet carrier, the maximum equivalent stress, and the torsional angle of the gear shaft as the concerned performance. Among them, the mass of the planet carrier is obtained according to m = ρ×v, where m is the mass of the planet carrier, ρ is the material density of the planet carrier, and v is the volume of the planet carrier. The finite - element model of the planet carrier includes the planet - carrier main body and the gear shaft. The gear shaft and the planet carrier are connected by interference fit, and a local coordinate system is established on the gear shaft. The origin of the local coordinate system is located at the center of each planetary gear shaft; the Z - axis points downward along the axial direction of the gear shaft; the Y - axis points towards the center of the gear shaft along the axis of the planet carrier; the X - axis forms a right - hand coordinate system with the Y - axis and the Z - axis.

[0077] Figure 5 is a schematic diagram of the topology optimization result of the planet carrier provided by the present invention;

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

[0079] Establish the topology - optimization design area of the planet carrier and remove the material in the gear area of the planet carrier;

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

[0081] With the volume fraction, the maximum equivalent stress value, and the maximum torsional angle of the gear shaft as constraints, perform topology optimization on the topology - optimization design area with the minimum compliance as the optimization objective;

[0082] Among them, the maximum equivalent stress value as a constraint indicates that the maximum equivalent stress value after optimization is less than the maximum equivalent stress value calculated in the initial scheme, and the maximum torsional angle of the gear shaft as a constraint indicates that the maximum torsional angle of the gear shaft after optimization is less than the maximum torsional angle calculated in the initial scheme.

[0083] According to the structural design and functional requirements of the planet carrier, the gear shaft is installed with gears according to the functional requirements, and the material in the corresponding area needs to be removed; at the same time, according to the number of gear shafts to be installed, the number of axial arrays of the material distribution in the design area is determined, and the topology optimization design area is established. At the same time, considering that the gear shaft needs to install gears, the material in the area where the gears are installed in the middle of the planet carrier is removed, and according to the structural design requirements of the planet carrier, axisymmetric and radial draft manufacturing constraints are added to the topology optimization design area; taking the volume fraction, the maximum equivalent stress value and the torsional angle of the gear shaft as optimization constraints, and the minimum compliance as the optimization goal for topology optimization. The volume fraction, the maximum equivalent stress value and the torsional angle of the gear shaft mentioned here are three constraints. The volume fraction constraint is set according to how much of the volume of the structure (topology optimization design area) remains after weight reduction; the maximum equivalent stress constraint means that the maximum equivalent stress value after optimization is less than the maximum equivalent stress value calculated by the initial scheme; the torsional angle is similar to the maximum equivalent stress value, and the optimized value is less than the torsional angle calculated by the initial scheme.

[0084] The results of the structural topology optimization should clearly show the force flow transmission path in the planet carrier structure, and the structural interpretation should be carried out as much as possible with reference to the topology optimization results; the interpretation of the topology optimization results should be carried out as much as possible without increasing the existing process difficulty; the manufacturing process characteristics of the planet carrier should be fully considered, and there should be no large changes in the wall thickness dimension, that is, the thickness change should be gentle; the interpretation of the topology optimization results should take into account the structural design of the attached functions.

[0085] In some embodiments, the mapping relationship between the structural parameters of the planet carrier and the concerned performance is determined, including:

[0086] According to the points determined by the Latin hypercube method, a multiple quadratic regression model is established to fit the mapping relationship between the structural parameters and the concerned performance, and the expression of the mapping relationship is ;

[0087] where y n is the nth concerned performance, x i is the ith structural parameter, , , and are all fitting coefficients.

[0088] Build a joint simulation platform of software SolidWorks and Ansys Workbench to realize the automation of establishing a parametric geometric model in SolidWorks to building a finite element model simulation analysis of the planet carrier in Ansys Workbench and extracting the concerned performance. Based on the DOE experimental design, analyze the contribution values of the structural parameters of the planet carrier to the concerned performance, and identify the structure-sensitive parameters. When drawing the 3D model of the planet carrier, many dimensional parameters need to be given, such as fillet radius, thickness, length, etc. These are the structural parameters.

[0089] It should also be noted that the selection of the fitting coefficient is set according to the actual data, and this application does not make excessive limitations here.

[0090] Among them, taking all the variable structural parameters in the parametric model of the new version design scheme of the planet carrier as the input, and extracting the mass, maximum equivalent stress and torsional angle performance of the gear shaft of the planet carrier as the output, to conduct experimental design. The method for determining the sampling points in the experimental design is the Latin hypercube method, and its principle is that according to the number of inputs n, in the n-dimensional space, the coordinate interval of each dimension , , k ∈ [1, n] is evenly divided into m intervals, and each interval is denoted as , i ∈ [1, m].

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

[0092] Performing accuracy verification on the mapping relationship based on the average error, maximum error, root mean square error and determination coefficient between the corresponding relationship between the actual structural parameters of the planet carrier and the concerned performance and the mapping relationship;

[0093] When the average error, maximum error and root mean square error are all lower than the first preset value and the determination coefficient is higher than the preset value, it is determined that the accuracy verification passes, and the step of performing parameter optimization on the structural parameters based on the mapping relationship is entered.

[0094] Introduce the neural network RBF method, construct a high-precision surrogate model for the mapping relationship between the sensitive parameters of the planet carrier and the concerned performance, use the gradient optimization algorithm NLPQLP to perform lightweight design on the planet carrier, and verify the lightweight design through simulation.

[0095] Figure 6 It is a schematic diagram of the prediction accuracy of the performance index of a planet carrier surrogate model provided by the present invention;

[0096] In some embodiments, performing accuracy verification on the mapping relationship based on the average error, maximum error, root mean square error and determination coefficient between the corresponding relationship between the actual structural parameters of the planet carrier and the concerned performance and the mapping relationship includes:

[0097] Determine the average error between the corresponding relationship between k planet carrier structural parameters and the concerned performance and the mapping relationship, and the expression of the average error is ;

[0098] Determine the maximum error between the corresponding relationship between k planet carrier structural parameters and the concerned performance and the mapping relationship, and the expression of the maximum error is ;

[0099] Determine the root mean square error between the corresponding relationship and the mapping relationship of the k planetary carrier structure parameters and the concerned performance. The expression of the root mean square error is ;

[0100] Determine the coefficient of determination between the corresponding relationship and the mapping relationship of the k planetary carrier structure parameters and the concerned performance. The expression of the coefficient of determination is ;

[0101] where, f i is the actual concerned performance corresponding to the i-th planetary carrier structure parameter, is the concerned performance corresponding to the i-th planetary carrier structure parameter in the mapping relationship, k is the total number of planetary carrier structure parameters, is the average value of the actual concerned performance corresponding to the i-th planetary carrier structure parameter, E mean is the average error, E max is the maximum error, E RMS is the root mean square error, R 2 is the coefficient of determination.

[0102] where, the precision index E mean , E max , E RMS The smaller the value, the higher the precision of the surrogate model. And the closer the value of the precision index R 2 is to 1, the higher the precision of the surrogate model. To obtain a high-precision surrogate model, the following conditions need to be met: E mean ≤0.15, E max ≤0.15, E RMS ≤0.15, R 2 ≥0.9.

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

[0104] In some embodiments, parameter optimization is performed on the structural parameters based on the mapping relationship, including:

[0105] Taking the minimum mass of the planetary carrier formed by the structural parameters as the goal, determine the structural parameters after parameter optimization under the parameter optimization constraints. The structural parameters after parameter optimization are X = [x 1 , x 2 , …, x i , and the parameter optimization constraints are ;

[0106] where, x 1 is the first structural parameter, x 1max is the maximum value of the first structural parameter, x 1min is the minimum value of the first structural parameter, x 2 is the second structural parameter, x2max is the maximum value of the first structural parameter, x 2min is the minimum value of the first structural parameter, x i is the i-th structural parameter, x imax is the maximum value of the first structural parameter, x imin is the minimum value of the first structural parameter, θ(X) is the torsional angle of the gear shaft corresponding to the optimized structural parameter, θ initial is the torsional angle of the gear shaft of the initial planetary carrier scheme, stress(X) is the maximum equivalent stress value corresponding to the optimized structural parameter, stress initial is the maximum equivalent stress value of the initial planetary carrier scheme.

[0107] Find a combination of structural parameters to form X = [x 1 , x 2 , …, x i , when the mass reaches the minimum value, and the torsional angle of the gear shaft and the maximum equivalent stress value corresponding to this parameter combination are both smaller than those of the initial scheme, it is determined that the parameter optimization is successful. Further, it needs to be verified by simulation through Ansys Workbench software before it can be used as the subsequent planetary carrier size.

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

[0109] Among them, 4 is the fillet radius of the strut, 5 is the outward movement distance of the inner wall of the strut, 6 is the rotating shaft, 7 is the rotation angle 1, 8 is the rotation angle 2, 9 is the outward movement distance of the concave wall, 10 is the upper wall thickness, 11 is the lower wall thickness, 12 is the concave surface fillet radius, and 13 is the wall surface fillet radius.

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

[0111] Determine the sensitivity value between each structural parameter and the concerned performance, and the sensitivity value is positively correlated with the correlation between the structural parameter and the concerned performance;

[0112] Determine the structural parameters with sensitivity values greater than the preset sensitivity value as sensitive parameters;

[0113] Based on the mapping relationship, perform parameter optimization on the structural parameters, including:

[0114] Based on the mapping relationship, perform parameter optimization on the sensitive parameters.

[0115] There are dozens or hundreds of structural parameters of the planet carrier. Select the parameters that have a great impact on the performance for optimization, that is, identify sensitive parameters.

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

[0117] Derive the mapping relationship to obtain the derivative mapping relationship ;

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

[0119] where y n is the nth performance of concern, x i is the ith structural parameter, , , and are all fitting coefficients. Max(x i ) is the maximum value of the ith structural parameter, Min(x i ) is the minimum value of the ith structural parameter, and M xi is the main effect of the linear term of each structural parameter;

[0120] Determine the sensitivity value of each performance of concern to each structural parameter according to the main effect. The expression of the sensitivity value is , N xi is the sensitivity between the ith structural parameter and the performance of concern.

[0121] If the absolute value of M xi is greater than 5, it is a sensitive parameter for this performance. When the absolute values of N xi for all used performances are less than 5, it is a non-sensitive parameter. It can be obtained that the upper and lower wall thicknesses of the planet carrier, the fillet radius of the strut, the moving distance of the inner wall of the strut, the outward moving distance of the concave wall, and the rotation angle of the strut wall surface are sensitive parameters.

[0122] Figure 11 FIG.

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

[0124] A processor 22, configured to implement the steps of the above-mentioned structural design method of the planet carrier when executing a computer program.

[0125] For the introduction of the structural design device of the planet carrier provided in this application, please refer to the above-mentioned embodiments and will not be elaborated here.

[0126] In this specification, the various embodiments are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the various embodiments, reference can be made to each other. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple. For the relevant parts, reference can be made to the description in the method part.

[0127] It should also be noted that in this specification, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the existence of additional identical elements in the process, method, article or device comprising the element.

[0128] Those skilled in the art can further realize that the units and algorithm steps of the examples described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the examples have been generally described according to their functions in the above description. Whether these functions are executed in a hardware or software manner 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 implementation should not be considered to exceed the scope of the present invention.

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

Claims

1. A structural design method for a planet carrier, characterized in that: include: Determining a maximum equivalent stress value and a maximum gear shaft torsion angle under extreme working conditions according to the structure of the historical planet carrier, wherein the maximum equivalent stress value represents the strength of the planet carrier, and the maximum gear shaft torsion angle represents the stiffness of the planet carrier; Taking the volume fraction, the maximum equivalent stress value and the maximum gear shaft torsion angle as constraints and minimizing flexibility as an optimization goal, topology optimization is performed to obtain the structure of the planet carrier after topology optimization, wherein the flexibility is negatively correlated with the stiffness, and the volume fraction is the ratio of the volume of the planet carrier after topology optimization to the volume of the planet carrier before topology optimization; Determine a mapping relationship between structural parameters of the planet carrier and performance of interest, wherein the performance of interest includes a mass of the planet carrier, an equivalent stress value, and a torsion angle of a gear shaft; Optimizing the structural parameters based on the mapping relationship; When the equivalent stress value and the gear shaft torsion angle corresponding to the structural parameters after parameter optimization are smaller than the equivalent stress value and the gear shaft torsion angle before parameter optimization, the planet carrier is manufactured according to the structure of the planet carrier after topology optimization and the structural parameters after parameter optimization.

2. The structural design method of a planetary carrier according to claim 1, characterized in that: According to the historical planet carrier structure, the maximum equivalent stress value and the maximum gear shaft torsion angle under extreme working conditions are determined, including: Based on the geometric model of the initial solution of the planet carrier, adding load boundary conditions to the geometric model to establish the maximum equivalent stress value and the maximum gear shaft torsion angle of the planet carrier under the extreme working condition; Among them, the expression of the maximum equivalent stress value is: , is the maximum equivalent stress value, , and are the first, second and third principal stresses respectively, and the expression of the maximum gear shaft torsion angle is: , θ is the maximum gear shaft torsion angle, △ max is the maximum displacement of the local coordinate system in the X-axis direction, △ min is the minimum displacement in the X-axis direction of the local coordinate system, 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, 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, the Y axis points to the center of the gear shaft along the planet carrier axis, and the X axis, Y axis and Z axis form a right-handed coordinate system.

3. The structural design method of a planetary carrier according to claim 1, characterized in that: Taking the volume fraction, the maximum equivalent stress value and the maximum gear shaft torsion angle as constraints and minimizing flexibility as the optimization goal, topology optimization is performed to obtain the structure of the planet carrier after topology optimization, including: Establishing a topological optimization design area of ​​the planet carrier and removing material from the gear area of ​​the planet carrier; adding axisymmetric and radial draft manufacturing constraints to the topology optimization design region; Taking the volume fraction, the maximum equivalent stress value and the maximum gear shaft torsion angle as constraints and minimizing the flexibility as the optimization goal, topology optimization is performed in the topology optimization design area; Among them, the maximum equivalent stress value is the maximum equivalent stress value after constraint characterization optimization 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 is less than the maximum gear shaft torsion angle calculated by the initial scheme.

4. The structural design method of a planetary carrier according to claim 1, characterized in that: Determining a mapping relationship between the structural parameters of the planet carrier and the performance of interest includes: According to the adoption point determined by the Latin hypercube method, a mapping relationship between the multivariate quadratic regression model fitting structure parameters and the performance of interest is established. The expression of the mapping relationship is: ; Among them, y n is the nth performance of interest, x i is the i-th structural parameter, , , and All are fitting coefficients.

5. The structural design method of a planetary carrier according to claim 1, characterized in that: Before optimizing the structural parameters based on the mapping relationship, the method further includes: Verifying the accuracy of the mapping relationship based on the average error, maximum error, root mean square error and determination coefficient between the corresponding relationship between the actual planet carrier structural parameters and the performance of interest and the mapping relationship; When the average error, the maximum error and the error root mean square are all lower than a first preset value and the determination coefficient is higher than a preset value, it is determined that the accuracy check has passed, and the step of optimizing the structural parameters based on the mapping relationship is entered.

6. The structural design method of a planetary carrier according to claim 5, characterized in that: The mapping relationship is verified for accuracy based on the average error, maximum error, root mean square error and determination coefficient between the corresponding relationship between the actual planet carrier structural parameters and the performance of interest and the mapping relationship, including: Determine the average error between the corresponding relationship between k planet carrier structural parameters and the performance of interest and the mapping relationship, and the expression of the average error is: ; Determine the maximum error between the correspondence between k planet carrier structural parameters and the performance of interest and the mapping relationship, the expression of the maximum error is: ; Determine the root mean square error between the corresponding relationship between k planet carrier structural parameters and the performance of interest and the mapping relationship. The expression of the root mean square error is: ; Determine the coefficient of determination between the corresponding relationship between k planet carrier structural parameters and the performance of interest and the mapping relationship. The expression of the coefficient of determination is: ; Among them, f i is the actual performance of interest corresponding to the i-th planet carrier structural parameter, is the performance of interest corresponding to the i-th planet carrier structural parameter in the mapping relationship, k is the total number of the planet carrier structural parameters, is the average value of the actual performance of interest corresponding to the i-th planet carrier structural parameter, E mean is the average error, E max is the maximum error, E RMS is the root mean square error, R 2 is the determination coefficient.

7. The structural design method of a planetary carrier according to claim 1, characterized in that: Optimizing the structural parameters based on the mapping relationship includes: Taking the minimum mass of the planet carrier formed by the structural parameters as the goal, the structural parameters after parameter optimization are determined under the parameter optimization constraints. The structural parameters after parameter optimization are X=[x1,x2,…,x i ], the parameter optimization constraints are ; Among them, x1 is the first structural parameter, x 1max is the maximum value of the first structural parameter, x 1min is the minimum value of the first structural parameter, x2 is the second structural parameter, x 2max is the maximum value of the first structural parameter, x 2min is the minimum value of the first structural parameter, x i is the i-th structural parameter, x imax is the maximum value of the first structural parameter, x imin is the minimum value of the first structural parameter, θ(X) is the gear shaft torsion angle corresponding to the structural parameter after parameter optimization, θ initial is the gear shaft torsion angle of the initial planet carrier solution, stress(X) is the maximum equivalent stress value corresponding to the structural parameters after parameter optimization, stress initial is the maximum equivalent stress value of the initial solution of the planet carrier.

8. The structural design method of a planet carrier according to any one of claims 1 to 7, characterized in that: After determining the mapping relationship between the structural parameters of the planet carrier and the performance of interest, the method further includes: Determining 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; Determine a structural parameter whose sensitivity value is greater than a preset sensitivity value as a sensitive parameter; Optimizing the structural parameters based on the mapping relationship includes: The sensitive parameters are optimized based on the mapping relationship.

9. The structural design method of a planet carrier according to claim 8, characterized in that: Determining the sensitivity value between each of the structural parameters and the performance of interest, including: The mapping relationship Perform derivation and obtain the derivation mapping relationship ; The main effect of the linear term of each structural parameter is determined according to the derivative mapping relationship, and the expression of the main effect is M xi =β i dx i , dx i =Max(x i )- Min(x i ); Among them, y n is the nth performance of interest, x i is the i-th structural parameter, , , and are all fitting coefficients, Max(x i ) is the maximum value of the i-th structural parameter, Min(x i ) is the minimum value of the i-th structural parameter, M xi is the main effect of the linear term for each of the structural parameters; The sensitivity value of each performance of interest to each structural parameter is determined according to the main effect, and the expression of the sensitivity value is: , N xi is the sensitivity of the i-th structural parameter to the performance of interest.

10. A structural design device for a planetary carrier, characterized in that: include: Memory for storing computer programs; A processor, configured to implement the steps of the structural design method of a planetary carrier as claimed in any one of claims 1 to 9 when executing the computer program.

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