Design method for hydraulic oil tank bottom shell of new energy automobile

Abstract

The invention discloses a new energy automobile hydraulic oil tank bottom shell design method, and relates to the technical field of automobile hydraulics, and the method comprises the steps: constructing a bottom shell geometric model, carrying out three-dimensional fluid thermal-mechanical coupling simulation and stress response evaluation on a preliminary flow channel planning scheme, and obtaining a comprehensive performance set of a bottom shell; according to the comprehensive performance set of the bottom shell, the runner trend and the section form are adjusted, and an optimized runner planning scheme is generated; according to the optimized flow channel planning scheme, working state data of the hydraulic oil tank are input into a bottom shell geometric model for digital simulation and virtual test platform verification, and a bottom shell performance parameter set is obtained; and based on the bottom shell performance parameter set, carrying out lightweight and stress path reconstruction on the bottom shell geometric model to obtain a bottom shell structure, and carrying out strength heat resistance and fatigue adaptability evaluation on a preset bottom shell material to obtain a bottom shell material type selection scheme. According to the scheme of light weight of the bottom shell and optimization of the stress path, material consumption can be reduced, and the energy efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of automotive hydraulic technology, and in particular to a design method for the bottom shell of a hydraulic oil tank in a new energy vehicle. Background Technology

[0002] With the widespread application of hydraulics in industry and automotive fields, hydraulic tanks, as a crucial component, play a vital role in ensuring the stability and efficiency of hydraulic systems. The design of hydraulic tanks not only needs to consider their hydrodynamic characteristics but also must effectively manage heat and stress to ensure the normal operation of the hydraulic mechanism. Furthermore, with the promotion of new energy vehicles, the requirements for materials and structures of hydraulic tanks operating under high load and high flow environments have become more stringent. In recent years, hydraulic tank design has increasingly adopted multidisciplinary joint optimization methods, combining fluid mechanics, thermodynamics, and mechanical simulation technologies to achieve accurate prediction and optimization of the overall performance of hydraulic tanks.

[0003] However, existing hydraulic tank designs often focus on optimizing a single area, neglecting the comprehensive consideration of flow channels, thermal management, and structural stress. When dealing with complex working conditions, existing technologies cannot fully achieve coordinated optimization of fluid flow, heat dissipation, and structural strength, resulting in unstable temperature control, low energy efficiency, and insufficient fatigue life of hydraulic tanks in actual operation. Summary of the Invention

[0004] In view of the aforementioned existing problems, the present invention is proposed.

[0005] Therefore, this invention provides a design method for the bottom shell of a hydraulic oil tank in new energy vehicles, which solves the problem of insufficient coordination and optimization of flow channel layout, thermal management and structural strength in the design of the bottom shell of a hydraulic oil tank.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: This invention provides a design method for the bottom shell of a hydraulic oil tank in a new energy vehicle. The method includes: collecting working state data of the hydraulic oil tank; performing performance analysis on the working state data to obtain functional requirements and constraints; spatially arranging and allocating the internal flow path and key structural positions of the bottom shell according to the functional requirements and constraints to generate a preliminary flow path planning scheme; constructing a geometric model of the bottom shell; performing three-dimensional fluid-thermal-coupling simulation and stress response evaluation on the preliminary flow path planning scheme to obtain a comprehensive performance set of the bottom shell; and adjusting the flow path direction according to the comprehensive performance set of the bottom shell. Based on the cross-sectional shape, an optimized flow channel planning scheme is generated. According to the optimized flow channel planning scheme, the working state data of the hydraulic oil tank is input into the bottom shell geometric model for digital simulation and virtual test platform verification, resulting in a bottom shell performance parameter set. Based on the bottom shell performance parameter set, the bottom shell geometric model is lightweighted and the force path is reconstructed to obtain the bottom shell structure. The strength, heat resistance, and fatigue adaptability of the pre-set bottom shell materials are evaluated to obtain a bottom shell material selection scheme. Based on the bottom shell structure and bottom shell material selection scheme, the comprehensive performance set of the bottom shell is verified, resulting in a verification report and feedback information.

[0007] As a preferred embodiment of the design method for the bottom shell of the hydraulic oil tank in new energy vehicles according to the present invention, the specific steps for obtaining the functional requirements and constraints are as follows: The working status data of the hydraulic oil tank includes pressure timing data, oil temperature data, oil flow rate data, and vehicle operating condition data. Based on pressure time series data and oil flow data, the maximum bearing pressure, maximum flow rate and thermal load of the hydraulic oil tank are calculated, and the maximum bearing pressure, maximum flow rate and thermal load are compared with the corresponding change trends in the working status data of the hydraulic oil tank to obtain the functional requirements of the hydraulic oil tank. Based on the hydraulic fluid temperature data and the vehicle's operating conditions data, the minimum heat dissipation area and heat resistance temperature range of the hydraulic oil tank are calculated. The minimum heat dissipation area and heat resistance temperature range are then correlated with the temperature changes in the hydraulic oil tank's operating conditions data to obtain the constraints of the hydraulic oil tank.

[0008] As a preferred embodiment of the design method for the bottom shell of the hydraulic oil tank in new energy vehicles according to the present invention, the specific steps for generating the preliminary flow channel planning scheme are as follows: Based on the functional requirements and constraints of the hydraulic oil tank, the outer contour of the bottom shell, the starting position of the flow channel, the internal flow channel path and the position of key structures are determined, and the basic layout of the bottom shell space and flow channel path is obtained. Perform multi-objective optimization calculations on the basic layout of the bottom shell space and flow channel path to obtain the flow channel orientation and cross-sectional shape; Using a genetic algorithm, the flow channel orientation and cross-sectional shape are assigned positions and structural reinforcements are arranged to generate a preliminary flow channel planning scheme.

[0009] As a preferred embodiment of the design method for the bottom shell of the hydraulic oil tank in new energy vehicles according to the present invention, the specific steps for constructing the geometric model of the bottom shell are as follows: The functional layers of the bottom shell are determined based on the maximum bearing pressure, maximum flow rate, and thermal load of the hydraulic oil tank. Based on the functional layer, the outer contour of the bottom shell, the starting position of the flow channel, the flow channel path inside the bottom shell and the key structural positions are analyzed and optimized to determine the structural layer and material layer of the bottom shell. Based on the functional layer, structural layer, and material layer, a geometric model of the bottom shell is constructed using 3D modeling tools.

[0010] As a preferred embodiment of the design method for the bottom shell of the hydraulic oil tank in new energy vehicles according to the present invention, the specific steps for obtaining the comprehensive performance set of the bottom shell are as follows: The preliminary flow channel planning scheme is input into the bottom shell geometric model, and a three-dimensional fluid-thermal coupling simulation is performed on the bottom shell of the hydraulic oil tank to obtain the thermodynamic performance indicators. The structural stress analysis of the bottom shell geometric model was carried out using the finite element method to obtain the structural performance indicators; The thermal performance indicators and structural performance indicators are integrated into a comprehensive performance set for the bottom shell.

[0011] As a preferred embodiment of the design method for the bottom shell of the hydraulic oil tank in new energy vehicles according to the present invention, the specific steps for generating the optimized flow channel planning scheme are as follows: Thermal conduction analysis and topology optimization are performed on the overall performance set of the bottom shell to identify the weak points and optimization targets in the flow channel; Based on the weak points and optimization objectives, the flow channel direction and cross-sectional shape are adjusted to obtain the adjusted flow channel direction and cross-sectional shape. The adjusted flow channel orientation and cross-sectional shape are optimized using a multi-objective optimization algorithm to generate an optimized flow channel planning scheme.

[0012] As a preferred embodiment of the design method for the bottom shell of the hydraulic oil tank in new energy vehicles according to the present invention, the specific steps for obtaining the bottom shell performance parameter set are as follows: Based on the optimized flow channel planning scheme, the working status data of the hydraulic oil tank is input into the bottom shell geometric model to perform high-fidelity three-dimensional fluid-thermal coupling working condition simulation and obtain the working condition flow channel performance index. Structural response analysis of the bottom shell geometric model under measured loads was performed to obtain structural performance indicators under working conditions. The performance indicators of the flow channel and the structural performance indicators under working conditions are input into the virtual test platform for verification, and the performance parameter set of the bottom shell is obtained.

[0013] As a preferred embodiment of the design method for the bottom shell of the hydraulic oil tank in new energy vehicles according to the present invention, the specific steps for obtaining the bottom shell structure are as follows: Based on the performance parameter set of the bottom shell, the bottom shell geometric model is lightweighted using a topology optimization algorithm to obtain an optimized bottom shell geometric model. The optimized bottom shell geometry model is reconstructed to obtain the structural reinforcement region and the bottom shell force path. The structural reinforcement area and the stress path of the bottom shell are adjusted to obtain the bottom shell structure.

[0014] As a preferred embodiment of the design method for the bottom shell of the hydraulic oil tank in new energy vehicles according to the present invention, the specific steps for obtaining the bottom shell material selection scheme are as follows: Based on the performance parameter set of the bottom shell, a strength analysis is performed on the structural performance index under working conditions to obtain the strength requirements for the selected bottom shell material; Thermal conduction analysis was performed on the performance indicators of the flow channel under operating conditions to obtain the heat resistance requirements of the bottom shell material; Based on pressure time series data and vehicle operating condition data, the fatigue life of the bottom shell material is estimated using the SN curve method, and the fatigue life requirement of the bottom shell material is obtained. Select a hydraulic tank bottom shell material that meets the strength, heat resistance, and fatigue life requirements from the pre-selected bottom shell materials to generate a bottom shell material selection scheme.

[0015] As a preferred embodiment of the hydraulic oil tank bottom shell design method for new energy vehicles according to the present invention, the specific steps for obtaining the verification report and feedback information are as follows: Based on the bottom shell structure and bottom shell material selection scheme, the bottom shell geometric model is used to conduct preliminary performance simulation of the comprehensive performance set of the bottom shell, and the preliminary performance simulation results are obtained. The preliminary performance simulation results of the bottom shell were optimized and adjusted using a genetic algorithm to obtain an optimized bottom shell planning scheme. The optimized bottom shell planning scheme is input into the virtual test platform for long-term working condition verification, a verification report is generated, and the verification report is compared with the preset planning target to obtain improvement suggestions and feedback information.

[0016] The beneficial effects of this invention are as follows: By combining the working state data of the hydraulic oil tank with various performance requirements, the geometric model of the bottom shell is optimized. Advanced simulation methods are used to perform detailed simulations of the flow path, structural stress, and heat conduction characteristics. This not only improves flow efficiency and reduces heat loss but also ensures the structural safety of the bottom shell under different working conditions. Most importantly, the comprehensive performance set of the bottom shell is obtained through feedback from actual working data and verification via a virtual testing platform, ensuring the reliability of the solution. Through this process, the stability of the hydraulic oil tank under high load and high flow environment can be effectively improved, energy loss reduced, and heat dissipation capacity enhanced. This improves overall working efficiency while extending the service life of the hydraulic oil tank. Furthermore, the lightweight design of the bottom shell and the optimization of the stress path reduce material consumption and improve energy efficiency. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. 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.

[0018] Figure 1 A flowchart for the design method of the bottom shell of the hydraulic oil tank for new energy vehicles.

[0019] Figure 2 A flowchart for generating a preliminary flow channel planning scheme.

[0020] Figure 3 A flowchart for generating the set of performance parameters for the bottom shell.

[0021] Figure 4 A flowchart for generating a bottom shell material selection scheme and verifying a comprehensive performance set. Detailed Implementation

[0022] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0023] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0024] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0025] Reference Figures 1-4 As one embodiment of the present invention, this embodiment provides a design method for the bottom shell of a hydraulic oil tank in a new energy vehicle, including the following steps: S1. Collect the working status data of the hydraulic oil tank, perform performance analysis on the working status data of the hydraulic oil tank, and obtain functional requirements and constraints. S1.1: The working status data of the hydraulic oil tank includes pressure timing data, oil temperature data, oil flow data, and vehicle operating condition data; It should be noted that pressure time series data refers to the recorded data of oil pressure changes over time in the hydraulic tank, including pressure fluctuations, maximum and minimum load pressure, pulse pressure, and periodic pressure changes. Oil temperature data is data reflecting the thermal management and heat dissipation effect of the oil in the hydraulic tank as the oil temperature changes over time. It includes oil density, instantaneous oil temperature, maximum and minimum operating temperatures, temperature fluctuations, and average temperature as the oil temperature changes. Oil flow data refers to the rate of oil flow in the hydraulic tank, including instantaneous flow, maximum and minimum flow, flow fluctuations, and average flow. Vehicle operating condition data refers to the hydraulic tank operating data related to the vehicle's operating status, reflecting the vehicle's demand on the hydraulic tank under various driving conditions, including vehicle speed, load status, driving mode, and ambient temperature.

[0026] S1.2: Based on pressure time series data and oil flow data, calculate the maximum bearing pressure, maximum flow rate and thermal load of the hydraulic oil tank, and compare the maximum bearing pressure, maximum flow rate and thermal load with the corresponding change trends in the working status data of the hydraulic oil tank to obtain the functional requirements of the hydraulic oil tank. Specifically, extreme value statistics are performed on the pressure time series data and oil flow data to determine the maximum bearing pressure of the hydraulic oil tank under different working conditions and the maximum flow rate that the hydraulic oil tank can withstand during operation. Based on the maximum bearing pressure and maximum flow rate, the heat load generated by the oil under the maximum flow rate and bearing pressure is calculated. By comparing the corresponding change trends of the maximum bearing pressure, maximum flow rate, and heat load with the pressure time series data and oil flow data of the hydraulic oil tank item by item, the performance requirements of the hydraulic oil tank in terms of pressure bearing capacity, flow capacity, and heat load bearing capacity are extracted as functional requirements.

[0027] The expression for calculating the heat load generated by the oil at maximum flow rate and bearing pressure is as follows: ; in, This indicates the heat load, reflecting the heat generated by the hydraulic oil tank under maximum flow and maximum load pressure. Indicates the maximum bearing pressure; Indicates the maximum flow rate of the hydraulic oil tank; The heat dissipation efficiency of a hydraulic oil tank is estimated by simulating the temperature distribution and heat transfer process of the oil flow using fluid dynamics simulation and thermodynamic models. This indicates the absolute temperature of the oil entering the tank, expressed in Kelvin (K). This indicates the absolute temperature at which the oil flows out of the tank, measured in Kelvin (K).

[0028] It should be noted that the heat load conversion formula is based on the principle of energy conservation in hydraulic tanks. It assumes that all viscous dissipation and throttling losses generated by the oil under load pressure and flow conditions are converted into heat, and corrects the heat accumulation efficiency under different operating temperature levels with a temperature ratio term, thus forming an empirical conversion formula for heat load estimation. Different operating conditions include maximum load condition, normal load condition, low load condition, high temperature condition, high flow transient condition, high pressure transient condition, and steady state condition.

[0029] S1.3: Based on the oil temperature data and the vehicle operating condition data, calculate the minimum heat dissipation area and heat resistance temperature range of the hydraulic oil tank, and correlate the minimum heat dissipation area and heat resistance temperature range with the temperature change in the working condition data of the hydraulic oil tank to obtain the constraint conditions of the hydraulic oil tank.

[0030] Specifically, based on the oil temperature data and vehicle operating condition data, the minimum heat dissipation area of ​​the hydraulic oil tank under maximum load conditions is calculated. Based on the highest and lowest operating temperatures of the oil, the heat resistance temperature range of the hydraulic oil tank is calculated. By correlating the minimum heat dissipation area and heat resistance temperature range with the temperature changes in the oil temperature data and vehicle operating condition data, the limiting requirements of the hydraulic oil tank in terms of heat dissipation area and heat resistance temperature are extracted, thereby obtaining the constraints of the hydraulic oil tank.

[0031] The expressions for calculating the minimum heat dissipation area and heat resistance temperature range of a hydraulic oil tank are as follows: ; ; in, This indicates the minimum heat dissipation area of ​​the hydraulic oil tank under maximum load conditions; This represents the equivalent convective heat transfer coefficient between the oil and the bottom shell wall. Indicates the heat resistance temperature range; This indicates the absolute temperature of the oil inlet, in K, with a sampling period of 10–100 ms; This indicates the absolute temperature of the oil outlet, in K, with a sampling period of 10–100 ms.

[0032] It should be noted that the steps for setting the equivalent convective heat transfer coefficient include: determining the heat exchange mode between the oil and the bottom shell wall based on the working state and conditions of the hydraulic oil tank; if it is natural convection, a lower value is used; if it is forced convection, a higher value is used; calibration experiments are conducted based on the heat exchange efficiency of the hydraulic oil tank under different working conditions to determine the heat transfer rate between the oil and the bottom shell wall, thereby obtaining the convective heat transfer coefficient between the oil and the bottom shell; the exemplary value range is 80–300 W·m. -2 ·K -1 The lower value is applicable to natural convection conditions, while the higher value is applicable to forced convection conditions. The value is determined based on the specific working conditions of the hydraulic oil tank, the fluid flow properties, and the calibration results of experimental data, ensuring that the equivalent convective heat transfer coefficient can effectively reflect the heat transfer efficiency inside the hydraulic oil tank under different working environments.

[0033] S2. Based on functional requirements and constraints, spatially arrange and allocate the flow path and key structural positions inside the bottom shell to generate a preliminary flow path planning scheme. S2.1: Based on the functional requirements and constraints of the hydraulic oil tank, determine the outer contour of the bottom shell, the starting position of the flow channel, the flow path inside the bottom shell and the position of key structures, and obtain the basic layout of the bottom shell space and the flow path. Specifically, based on pressure time-series data and oil flow data, regression analysis is used to fit the maximum bearing pressure, maximum flow rate, and oil temperature range of the hydraulic tank to determine the outer contour of the bottom shell. Fluid dynamics simulation of the oil flow distribution is then performed to determine the starting position of the flow channels in the bottom shell. Through fluid dynamics analysis and heat conduction simulation, the internal flow path and cross-sectional shape of the bottom shell are determined. Key structural positions of the bottom shell are then allocated and reinforced to ensure stable operation under different working conditions, thus obtaining the basic layout of the bottom shell space and flow path.

[0034] It should be noted that the critical structural locations refer to the parts of the hydraulic tank bottom shell that bear the maximum pressure, flow load, and thermal load, located at the beginning of the flow channel, the bend of the flow channel, the connection area, and the area where the bottom shell connects with other components.

[0035] S2.2: Perform multi-objective optimization calculations on the basic layout of the bottom shell space and flow channel path to obtain the flow channel direction and cross-sectional shape; Specifically, based on the functional requirements and constraints of the hydraulic tank, the basic layout of the flow path and the cross-sectional shape in the bottom shell space are parameterized as a particle swarm. Each individual in the particle swarm represents a scheme of flow path orientation and cross-sectional shape. In the process of adjusting the particle swarm using the particle swarm optimization algorithm, based on fluid dynamics simulation and thermodynamic model, multiple optimization objectives are set, including flow stability, pressure loss, thermal management efficiency, and structural strength. The influence of flow stability and heat transfer efficiency on the flow path orientation and cross-sectional shape is taken as the main objective, and structural strength is taken as the constraint. The objectives of flow stability, pressure loss, thermal management efficiency, and structural strength are combined in a weighted manner, and corresponding weights are set (e.g., flow stability is 40%, pressure loss is 30%, thermal management efficiency is 20%, and structural strength is 10%). In the particle swarm optimization algorithm, each individual solution is adjusted to ensure that the flow path orientation and cross-sectional shape of the hydraulic tank can maximize the stability of fluid flow, reduce pressure loss, improve thermal management efficiency, and enhance the strength and durability of the structure under working conditions, thus obtaining the optimal flow path orientation and cross-sectional shape.

[0036] It should be noted that the training process of the thermodynamic model is as follows: outliers are removed and normalized from the hydraulic tank's operating state data. Using known data (such as temperature changes and heat flux density) and combined with the hydraulic tank's heat dissipation efficiency, the thermodynamic model parameters (such as specific heat capacity, heat exchange coefficient, and heat transfer efficiency) are adjusted through an iterative optimization algorithm to ensure that the thermodynamic model can accurately simulate the thermal behavior of the oil. During the training process, the accuracy of the thermodynamic model is verified by comparing it with actual measurement data. The thermodynamic model parameters are adjusted according to the errors until the output thermodynamic performance indicators match the actual data, thus completing the training of the thermodynamic model.

[0037] S2.3: Using a genetic algorithm, the flow channel orientation and cross-sectional shape are assigned positions and structural reinforcements are arranged to generate a preliminary flow channel planning scheme.

[0038] Specifically, a fitness function is set according to the functional requirements and constraints of the hydraulic tank, and the flow efficiency, pressure loss, heat dissipation effect and structural strength of each layout scheme are evaluated using the fitness function. In each generation of iteration, excellent individuals are selected for crossbreeding according to the fitness function to explore more optimal solutions. After multiple generations of iterative optimization, a preliminary flow channel layout scheme that meets the functional requirements and has high flow efficiency, heat dissipation effect and structural strength is obtained.

[0039] It should be noted that the fitness function is based on the functional requirements and constraints of the hydraulic tank, defining multiple optimization objectives (including flow efficiency, pressure loss, heat dissipation, and structural strength). The values ​​of each objective are evaluated through fluid dynamics simulation and thermodynamic models. The flow efficiency objective is determined by minimizing the resistance of the oil flow; the pressure loss objective is measured by minimizing the energy loss of the fluid; the heat dissipation objective is set by improving heat transfer efficiency; and the structural strength objective is evaluated by the strength requirements of the bottom shell under maximum bearing pressure and flow load. The various objectives are integrated into the fitness function using a weighted average, with weights set according to the importance of each objective in the optimization process. The fitness function is used to evaluate the merits of each layout scheme. A particle swarm optimization algorithm is used to select the best-performing individuals in each iteration for mating and reproduction, gradually improving the flow channel layout until the optimal scheme that meets the functional requirements of the hydraulic tank and possesses high flow efficiency, heat dissipation, and structural strength is found.

[0040] S3. Construct a bottom shell geometric model, perform three-dimensional fluid thermo-mechanical coupling simulation and stress response evaluation on the preliminary flow channel planning scheme, obtain the comprehensive performance set of the bottom shell, and adjust the flow channel direction and cross-sectional shape according to the comprehensive performance set of the bottom shell to generate an optimized flow channel planning scheme. S3.1: Determine the functional layers of the bottom shell based on the maximum bearing pressure, maximum flow rate, and thermal load of the hydraulic oil tank; Specifically, the flow characteristics (velocity distribution, pressure distribution, and temperature distribution) of the hydraulic oil tank are simulated using fluid dynamics simulation to describe the flow behavior of the oil inside the hydraulic oil tank. Based on the flow path and pressure distribution of the fluid during operation, the strength requirements of the bottom shell functional layer are determined. Based on the working state data of the hydraulic oil tank, the heat transfer path and distribution of the oil during flow are analyzed through heat conduction analysis to determine the heat dissipation capacity of the bottom shell functional layer under different working conditions. According to the heat dissipation capacity and strength requirements, a multi-objective optimization algorithm is used to lay out the functional layers of the bottom shell, so that the hydraulic oil tank can stably and effectively dissipate heat and maintain structural stability during actual operation, thus determining the functional layers of the bottom shell.

[0041] S3.2: Based on the functional layer, perform structural analysis and optimization on the outer contour of the bottom shell, the starting position of the flow channel, the flow channel path inside the bottom shell and the key structural positions, and determine the structural layer and material layer of the bottom shell; Specifically, based on the functional layer, the working state data of the hydraulic oil tank is quantified. According to the fluid behavior of the hydraulic oil tank under different working conditions, the flow path, velocity distribution, pressure distribution, and temperature distribution of the hydraulic oil tank are determined. An optimization algorithm is then used to gradually adjust the outer contour of the bottom shell, enabling effective heat dissipation of the fluid during operation and forming a bottom shell contour that meets functional requirements and constraints. Based on functional requirements, a topology optimization method is used to analyze the starting position of the flow channels and the internal flow paths of the bottom shell, identifying the key structural locations of the bottom shell. Structural stress analysis is performed on the flow paths and key structural locations to evaluate stress, deformation, and fatigue life under different working conditions, ensuring that the bottom shell can withstand the maximum pressure and flow load of the hydraulic oil tank during actual operation. Simultaneously, by accessing a material performance database, bottom shell materials that meet functional requirements and constraints are selected. Based on the strength, heat resistance, and fatigue life of the bottom shell materials, the material distribution in different regions is determined, resulting in the structural and material layers of the bottom shell.

[0042] It should be noted that the material properties database is a database that is organized, established, and maintained by sorting out and summarizing a large amount of experimental data, theoretical analysis, and standardized test results. It contains physical, mechanical, and thermal performance data (such as strength, heat resistance, and fatigue life) of various materials under different working conditions.

[0043] S3.3: Based on the functional layer, structural layer, and material layer, construct the bottom shell geometric model using 3D modeling tools.

[0044] Specifically, based on the functional layer, the flow state, pressure changes, and heat exchange effects of the fluid inside the hydraulic tank are simulated to determine the shape requirements and spatial layout of the hydraulic tank, resulting in the basic outline of the bottom shell. The key structural locations of the bottom shell are arranged according to the strength requirements of the structural layer to ensure they can withstand the maximum pressure and fluid load during hydraulic tank operation. Based on the selection of the material layer and its strength, heat resistance, and fatigue life, a suitable bottom shell material is selected, and its distribution is determined. Using 3D modeling tools, the basic outline of the bottom shell, the internal flow path, and the key structural locations are used as input to construct the geometric model of the bottom shell.

[0045] It should be noted that the iterative optimization process of the bottom shell geometric model is as follows: Based on the bottom shell's geometric characteristics, material properties, flow path, and structural requirements, the initial shape of the bottom shell geometric model is determined; the working state data of the hydraulic oil tank (such as maximum bearing pressure, maximum flow rate, and oil temperature) is input into the bottom shell geometric model for adaptive adjustment; under known working conditions, the working state data of the hydraulic oil tank is used to iteratively optimize the bottom shell geometric model so that the structural strength, thermal management efficiency, and flow stability of the bottom shell under different working conditions meet the strength requirements, heat resistance requirements, and fatigue life requirements, thus obtaining a bottom shell geometric model that meets performance standards.

[0046] S3.4: Input the preliminary flow channel planning scheme into the bottom shell geometric model, perform three-dimensional fluid-thermal coupling simulation on the bottom shell of the hydraulic oil tank, and obtain the thermodynamic performance indicators; Specifically, the preliminary flow channel planning scheme is applied to the bottom shell geometric model. The flow channel path, temperature distribution and heat transfer efficiency in the bottom shell geometric model are simulated through three-dimensional fluid dynamics simulation. During the simulation, based on the flow characteristics of the oil under different working conditions (flow velocity distribution, pressure distribution, temperature distribution and flow resistance), the heat transfer process and flow loss during the oil flow are described using the principle of energy conservation, and thermodynamic performance indicators including flow loss, temperature distribution, heat transfer efficiency and heat dissipation performance are obtained.

[0047] S3.5: The structural stress analysis of the bottom shell geometric model is carried out by finite element analysis to obtain the structural performance index; Specifically, based on the hydraulic tank's operating status data, maximum bearing pressure, maximum flow rate, and thermal load, boundary conditions for the bottom shell under different load conditions are set. A mesh generation tool is used to mesh the bottom shell's geometric model to ensure that the mesh accuracy is sufficient to accurately simulate the stress conditions. The finite element analysis method is used to perform structural stress analysis on the bottom shell, obtaining the stress distribution, deformation, and fatigue life of the bottom shell under pressure, flow rate, and temperature changes, and obtaining structural performance indicators that include stress distribution, deformation, and fatigue life.

[0048] S3.6: Integrate the thermal performance indicators and structural performance indicators into a comprehensive performance set for the bottom shell.

[0049] Specifically, based on the functional requirements and constraints of the bottom shell, the thermal performance indicators and structural performance indicators are weighted and prioritized to determine the stability and reliability of the bottom shell under different working conditions, thereby integrating them into a comprehensive performance set of the bottom shell.

[0050] S3.7: Perform heat conduction analysis and topology optimization on the comprehensive performance set of the bottom shell to obtain the weak links and optimization targets in the flow channel; Specifically, the heat transfer path inside the bottom shell is simulated through three-dimensional heat conduction simulation. Under different operating temperature boundary conditions, the propagation and distribution of heat during oil flow are simulated to identify areas with poor heat dissipation in the flow channel as weak links. The weak links are then optimized using topology optimization methods to adjust the cross-sectional shape and flow path distribution of the flow channel, so that the flow channel can distribute heat more evenly and ensure that the heat dissipation capacity of the hydraulic oil tank reaches the optimal level under different operating conditions, thereby determining the optimization target.

[0051] S3.8: Based on the weak points and optimization objectives, adjust the flow channel direction and cross-sectional shape to obtain the adjusted flow channel direction and cross-sectional shape; Specifically, based on weak links and optimization objectives, areas with low flow efficiency, high heat loss, and insufficient heat dissipation in the flow channel are identified. Through fluid dynamics simulation and heat conduction analysis, the heat transfer and flow characteristics during the oil flow process are simulated to determine the flow channel direction and cross-sectional shape that need to be improved. According to the functional requirements and constraints of the hydraulic oil tank, the starting position, direction, width, and shape of the flow channel are adjusted to ensure that the flow channel path can effectively improve flow efficiency, reduce heat loss, and optimize heat dissipation, resulting in the adjusted flow channel direction and cross-sectional shape.

[0052] S3.9: Optimize the adjusted flow channel direction and cross-sectional shape using a multi-objective optimization algorithm to generate an optimized flow channel planning scheme.

[0053] Specifically, based on the adjusted flow channel direction and cross-sectional shape, multiple optimization objectives (including flow efficiency, heat transfer effect and structural strength) are defined, and a multi-objective optimization algorithm is applied to weigh each optimization objective and iteratively optimize the flow channel path and cross-sectional shape to meet the functional requirements and constraints of the hydraulic tank, thereby generating an optimized flow channel planning scheme.

[0054] S4. Based on the optimized flow channel planning scheme, input the working status data of the hydraulic oil tank into the bottom shell geometric model for digital simulation and virtual test platform verification to obtain the bottom shell performance parameter set; S4.1: Based on the optimized flow channel planning scheme, input the working status data of the hydraulic oil tank into the bottom shell geometric model, perform high-fidelity three-dimensional fluid-thermal coupling working condition simulation, and obtain the working condition flow channel performance index. Specifically, based on the optimized flow channel planning scheme, the working state data of the hydraulic oil tank is input into the bottom shell geometric model. High-fidelity three-dimensional fluid-thermal coupling simulation is used to simulate the fluid flow and heat transfer process of the hydraulic oil tank under different working conditions. The pressure difference between the inlet and outlet of the flow channel, the uniformity of the flow velocity distribution, and the temperature difference between the flow channel wall and the surrounding environment are extracted from the simulation field. The temperature decay rate of the outer surface of the bottom shell geometric model and the heat dissipation area utilization rate are observed to determine the flow efficiency, heat loss and heat dissipation effect, and obtain the working condition flow channel performance index.

[0055] S4.2: Perform structural response analysis on the bottom shell geometric model under measured loads to obtain structural performance indicators under working conditions; Specifically, based on the pressure time series data in the hydraulic oil tank's working status data and the vehicle's operating condition data, the measured load is applied to the corresponding position of the bottom shell geometric model, and boundary conditions and constraints are set. The bottom shell geometric model is meshed using the finite element analysis method, and local mesh refinement is implemented at key structural locations through a mesh refinement mechanism to improve the accuracy of geometric detail representation. Stress peaks, deformation data, and fatigue cycle counts are extracted from the flow channel walls, connection parts, and support structures of the bottom shell geometric model. The calculation results under different operating conditions are integrated to obtain the structural performance indicators under different operating conditions.

[0056] S4.3: Input the performance indicators of the flow channel and the structural performance indicators under working conditions into the virtual test platform for verification to obtain the set of bottom shell performance parameters.

[0057] Specifically, the performance indicators of the flow channel and the structural components under operating conditions are imported into a virtual testing platform to perform multi-condition cyclic testing, simulating the comprehensive performance of the bottom shell geometric model under startup, steady-state operation, rapid acceleration, rapid deceleration, and shutdown conditions. Fluid flow state, heat exchange efficiency, structural deformation, and stress variation curves of the bottom shell geometric model under various operating conditions are extracted from the virtual testing platform. The degree of conformity between the measured response data of the bottom shell geometric model in the virtual testing platform and the preset performance thresholds is compared and analyzed, filtering out abnormal data and retaining valid performance parameters. Finally, the stability performance data under various operating conditions in the virtual testing platform are integrated to form a set of bottom shell performance parameters including flow channel efficiency parameters, heat dissipation capacity parameters, structural strength parameters, and fatigue life parameters.

[0058] It should be noted that the performance thresholds include the flow channel efficiency threshold, heat dissipation capacity range threshold, structural strength threshold, and fatigue life threshold. The flow channel efficiency threshold is set based on the functional requirements and constraints of the hydraulic tank. The specific setting steps include: determining the ideal flow efficiency range of the fluid in the hydraulic tank under different working conditions based on three-dimensional fluid thermo-coupling simulation; combining the maximum flow rate and flow requirements of the hydraulic tank, selecting a flow channel with stable ideal flow efficiency and able to maintain low pressure loss as the flow channel efficiency threshold. An exemplary value range is 85% to 95%. 85% is determined based on the minimum flow efficiency requirement of small oil flow loss and low energy consumption in the flow channel planning; 95% is set based on the upper limit of the optimal performance of flow channel energy efficiency in the flow channel optimization planning, ensuring maximum flow efficiency and avoiding structural instability caused by oversimplification of the planning. When the flow channel efficiency is lower than 85%, it will lead to excessive flow resistance, reduced operating efficiency of the hydraulic tank, and affect the long-term stability of the tank. When it is higher than 95%, the flow channel planning will be too simple, unable to effectively support complex workloads, and increase the risk of tank failure. The heat dissipation capacity threshold is set based on the heat dissipation requirements of the hydraulic oil tank during operation and the temperature control requirements under working conditions. The specific setting steps include: determining the heat dissipation requirement range of the hydraulic oil tank under maximum load pressure and maximum flow conditions based on the hydraulic oil tank's operating status data (such as maximum load pressure and maximum flow rate); combining this with the heat dissipation efficiency data of the hydraulic oil tank under different working conditions; and selecting the median value with stable performance within the heat dissipation requirement range as the heat dissipation capacity threshold. An exemplary value range is 70% to 85%. 70% is determined based on the hydraulic oil tank's ability to maintain the minimum temperature control requirements under high load conditions, while 85% is set based on the goal of effectively reducing oil temperature and avoiding excessive heat dissipation and energy waste under optimized planning. When the heat dissipation capacity is below 70%, the oil temperature will rise rapidly, causing the oil tank to overheat, affecting the oil viscosity and lubrication performance, and accelerating the wear of hydraulic oil tank components. When the heat dissipation capacity is above 85%, it will lead to unnecessary excessive heat dissipation, wasting energy and affecting the efficiency of the hydraulic oil tank. The structural strength threshold is set based on the maximum bearing pressure and flow load requirements of the hydraulic tank bottom shell material. The specific setting steps include: determining the maximum pressure and flow load range that the bottom shell needs to withstand based on the hydraulic tank's operating data; selecting a material strength level within the flow load range that meets functional requirements and constraints, based on the strength performance data of the selected material for the hydraulic tank bottom shell; and selecting a stable and well-performing intermediate value as the structural strength threshold based on experimental data and industry standards. An exemplary value range is 95% to 100%. A structural strength of 95% is determined based on the minimum safe strength requirement that the hydraulic tank bottom shell can withstand under maximum bearing pressure and external load, while 100% is determined based on the upper limit of material strength in the hydraulic tank's design, ensuring the maximum bearing capacity of the bottom shell under extreme working conditions and guaranteeing the long-term stability and safety of the structure. Below 95%, the bottom shell will crack and severely deform, causing the hydraulic tank to be unable to withstand high loads; above 100%, it will lead to excessive material strength, increasing weight and cost. The fatigue life threshold is set based on the working condition data of the hydraulic tank bottom shell and the cyclic loads that may be encountered during long-term use. The specific setting steps include: determining the fatigue performance requirements of the bottom shell material under different working conditions based on the maximum bearing pressure, flow rate, and temperature of the hydraulic tank under different working conditions; combining experimental data and industry standards; selecting a fatigue life range that meets durability requirements under different working conditions; and using the median fatigue life value within the fatigue life range that is stable and can withstand cyclic loads as the fatigue life threshold. An exemplary value range is 1. The fatigue life of 10,000 to 50,000 cycles is determined based on the minimum fatigue life requirement of the hydraulic tank under high load and frequent working conditions. The 50,000-cycle requirement is based on the long-term use requirements in the hydraulic tank design, ensuring that it can withstand multiple load cycles during long-term operation without fatigue failure, achieving optimal durability and reliability. Below 10,000 cycles, the bottom shell material will crack and fracture due to frequent stress cycles. Above 50,000 cycles, the bottom shell material will be over-strengthened, leading to increased cost and weight.

[0059] S5. Based on the performance parameter set of the bottom shell, the geometric model of the bottom shell is lightweighted and the stress path is reconstructed to obtain the bottom shell structure. The strength, heat resistance and fatigue adaptability of the pre-set bottom shell material are evaluated to obtain the bottom shell material selection scheme. S5.1: Based on the performance parameter set of the bottom shell, the bottom shell geometric model is lightweighted using a topology optimization algorithm to obtain an optimized bottom shell geometric model; Specifically, based on the flow channel efficiency parameters, heat dissipation capacity parameters, structural strength parameters, and fatigue life parameters in the bottom shell performance parameter set, material retention rate constraints and stiffness constraints are set on the bottom shell geometric model. The material distribution in the bottom shell geometric model is optimized by a topology optimization algorithm to ensure that unnecessary materials are removed while satisfying the material retention rate constraints and stiffness constraints, thus obtaining an optimized bottom shell geometric model.

[0060] S5.2: Perform force path reconstruction on the optimized bottom shell geometry model to obtain the structural reinforcement region and the force path of the bottom shell; Specifically, based on the optimized bottom shell geometric model and structural performance indicators under working conditions, the finite element analysis method is used to reconstruct the stress path of the bottom shell geometric model, analyze the stress distribution and deformation of the bottom shell under different working conditions, and identify the weak areas of the structure. Through the bottom shell geometric model, structural monitoring and analysis are performed on the stress distribution, deformation and fatigue life of the bottom shell to determine the structural reinforcement area of ​​the bottom shell and draw the stress path of the bottom shell to ensure the stability and reliability of the bottom shell under actual working conditions.

[0061] S5.3: Adjust the structure and force path of the structural reinforcement area and the bottom shell to obtain the bottom shell structure.

[0062] Specifically, based on the stress distribution and deformation of the bottom shell performance parameters, the stress gradient method is used to identify stress concentration points and weak points in the structural reinforcement area and the bottom shell force path. Finite element analysis is then used to locally strengthen the structural reinforcement area and the bottom shell force path, adding reinforcing ribs at stress concentration points and increasing material thickness at weak points. The bottom shell force path is then smoothed to eliminate abrupt structural changes. Finally, a 3D modeling tool is used to geometrically reconstruct the adjusted structural reinforcement area and bottom shell force path, forming a complete and closed shell structure while retaining necessary installation interfaces and connection features, resulting in a bottom shell structure that meets the requirements for strength, stiffness, and fatigue life.

[0063] S5.4: Based on the performance parameter set of the bottom shell, perform strength analysis on the structural performance index under working conditions to obtain the strength requirements of the selected bottom shell material; Specifically, based on the performance parameter set of the bottom shell, strength analysis is performed on the structural performance indicators under working conditions through stress-strain relationship and elastic modulus of material. During the analysis, boundary conditions for different working conditions are set according to the working state data of hydraulic oil tank to simulate the stress of bottom shell under pressure and flow rate changes and evaluate the load-bearing capacity of bottom shell material. Based on the load-bearing capacity of bottom shell material, the maximum stress point of bottom shell under maximum load is identified, and the strength requirements of bottom shell material are obtained.

[0064] S5.5: Perform heat conduction analysis on the performance indicators of the flow channel under operating conditions to obtain the heat resistance requirements of the bottom shell material; Specifically, when performing heat conduction analysis on the performance indicators of the flow channel under operating conditions, the flow and heat distribution of the hydraulic oil in the hydraulic tank are analyzed, and the corresponding heat conduction boundary conditions are set in combination with the geometry of the bottom shell. The heat conduction analysis method is used to simulate the heat transfer process between the oil and the bottom shell under different operating conditions, and the temperature change, heat flux density and heat exchange efficiency caused by the oil flow are calculated. Based on the analysis results, the temperature distribution and heat dissipation performance of the bottom shell under different operating conditions are identified, and the heat resistance requirements of the bottom shell material are determined to ensure the stability and long-term reliability of the bottom shell material in the actual working environment.

[0065] The expressions for calculating the temperature change, heat flux density, and heat exchange efficiency caused by oil flow are: ; ； ； in, This indicates the temperature change caused by the flow of oil. This indicates the heat gained by the oil during its flow. Indicates the mass flow rate of the oil; This indicates the specific heat capacity of the oil, obtained based on its composition and physical properties. This represents the heat flux density per unit area. This represents the amount of heat flowing through a certain area per unit of time; The unit area representing the region is derived through a combination of fluid dynamics simulation and experimental data; Indicates heat exchange efficiency; This refers to the effective heat transferred to the target object through heat exchangers and heat dissipation devices. This represents the total heat input.

[0066] S5.6: Based on the pressure time series data and the vehicle operating condition data, the fatigue life of the bottom shell material is estimated using the SN curve method to obtain the fatigue life requirements of the bottom shell material. Specifically, based on pressure time series data, the fatigue life of the bottom shell material is estimated using the SN curve method. The load cycle of the bottom shell under different working conditions is obtained, and combined with the vehicle operating condition data, the load intensity and fatigue cycle number of the bottom shell material during actual use are determined. Using the SN curve method, the load intensity is correlated with the corresponding fatigue cycle number. Referring to the material performance database, the minimum number of cycles required for the bottom shell material to avoid fatigue failure within the planned service life is determined, thus obtaining the required fatigue life of the bottom shell material.

[0067] S5.7: Select a hydraulic tank bottom shell material that meets the strength, heat resistance and fatigue life requirements from the pre-set bottom shell materials, and generate a bottom shell material selection scheme.

[0068] Specifically, based on the strength requirements of the bottom shell, materials that do not meet the high strength requirements are excluded from the pre-selected bottom shell materials. Based on the heat resistance requirements, heat-resistant materials that can operate stably in high-temperature environments are selected to ensure that the materials can maintain good thermal stability during the operation of the hydraulic oil tank. Based on the fatigue life requirements, materials that can withstand long-term fatigue loads and have excellent fatigue performance are selected from the heat-resistant materials to generate a bottom shell material selection scheme.

[0069] It should be noted that the pre-selected bottom shell material refers to a list of various materials that have been selected and are available during the hydraulic tank planning stage, and have certain basic performance requirements (such as strength, heat resistance, and corrosion resistance). The pre-selected bottom shell materials include common metal materials, alloy materials, and high-performance plastics, which can be screened and optimized according to different working environments and planning requirements.

[0070] S6. Verify the comprehensive performance set of the bottom shell according to the bottom shell structure and bottom shell material selection scheme, and obtain a verification report and feedback information.

[0071] S6.1: Based on the bottom shell structure and bottom shell material selection scheme, use the bottom shell geometric model to perform preliminary performance simulation on the comprehensive performance set of the bottom shell, and obtain preliminary performance simulation results; Specifically, based on the bottom shell structure and material selection scheme, the working state data of the hydraulic oil tank is matched with the bottom shell geometric model to ensure that the bottom shell geometric model can accurately reflect the actual use of the hydraulic oil tank under different working conditions. Based on the geometric characteristics and material properties of the bottom shell, boundary conditions are set on the bottom shell geometric model and multiphysics simulation is performed. During the simulation, the flow characteristics, temperature distribution and stress under different working conditions are collected to generate preliminary performance simulation results.

[0072] It should be noted that the geometric characteristics of the bottom shell are derived from the preliminary planning scheme and geometric model of the bottom shell, including the outer contour, size, thickness, flow channel layout, key structural positions, and relative positions of each component; the material properties of the bottom shell are derived from the bottom shell material selection scheme, including the strength, heat resistance, and fatigue life of the bottom shell material.

[0073] S6.2: The preliminary performance simulation results of the bottom shell are optimized and adjusted using a genetic algorithm to obtain an optimized bottom shell planning scheme; Specifically, the preliminary performance simulation results of the bottom shell are converted into chromosome encoding form using a genetic algorithm. A roulette wheel selection mechanism is used to select superior individuals that meet the functional requirements from the current population as parents. A uniform crossover operation is performed on the chromosomes of the parents to generate new offspring. Site mutation is applied to the chromosomes of the new offspring to randomly adjust key structural parameters. In each generation of genetic iteration, individuals that do not meet the functional requirements and constraints are eliminated. After multiple generations of genetic iteration, when the population performance tends to be stable and meets the functional requirements and constraints, the iteration process is terminated, and an optimized bottom shell planning scheme is formed.

[0074] S6.3: Input the optimized bottom shell planning scheme into the virtual test platform for long-term working condition verification, generate a verification report, and compare the verification report with the preset planning target to obtain improvement suggestions and feedback information.

[0075] Specifically, the optimized bottom shell planning scheme is input into a virtual test platform, which performs multi-condition cyclic testing to simulate the stress, fluid flow, and heat transfer efficiency of the bottom shell under different conditions. A verification report containing operating condition verification data is generated, and the operating condition verification data is compared with the preset planning target. When the operating condition verification data meets the planning target, optimization stops, and improvement suggestions and feedback information are obtained. When the operating condition verification data does not meet the planning target, the process reverts to the optimization of the flow channel planning scheme, and the flow channel layout, cross-sectional shape, and structural reinforcement arrangement are readjusted until all operating condition verification data meet the preset planning target and the optimization results are stable.

[0076] It should be noted that the planning objectives are set based on the functional requirements and constraints of the hydraulic tank, through analysis of operating data and oil flow characteristics. The planning objectives mainly include flow efficiency objectives, heat dissipation objectives, structural strength objectives, and fatigue life objectives. The flow efficiency objective is to ensure that the resistance of the oil in the flow channel is minimized. The heat dissipation objective is to ensure that the oil temperature is kept within a safe operating range. The structural strength objective is that the bottom shell can withstand the maximum bearing pressure and external load. The fatigue life objective is that the bottom shell can maintain good performance during long-term operation.

[0077] In summary, this invention optimizes the bottom shell geometric model by combining hydraulic tank operating data and various performance requirements. Advanced simulation methods are used to perform detailed simulations of flow paths, structural stress, and heat conduction characteristics. This not only improves flow efficiency and reduces heat loss but also ensures the structural safety of the bottom shell under different operating conditions. Most importantly, the comprehensive performance set of the bottom shell is obtained through feedback from actual operating data and verification via a virtual testing platform, ensuring the reliability of the solution. This process effectively improves the stability of the hydraulic tank under high load and high flow environments, reduces energy loss, and enhances heat dissipation, thereby improving overall working efficiency and extending the service life of the hydraulic tank. Furthermore, the lightweight design of the bottom shell and the optimization of the stress path reduce material consumption and improve energy efficiency.

[0078] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A design method for the bottom shell of a hydraulic oil tank in a new energy vehicle, characterized in that: include, Collect the working status data of the hydraulic oil tank, perform performance analysis on the working status data of the hydraulic oil tank, and obtain functional requirements and constraints; Based on functional requirements and constraints, the spatial arrangement and location allocation of the flow channel paths and key structural positions inside the bottom shell are carried out to generate a preliminary flow channel planning scheme. A geometric model of the bottom shell is constructed, and a three-dimensional fluid-thermal coupling simulation and stress response evaluation are performed on the preliminary flow channel planning scheme to obtain the comprehensive performance set of the bottom shell. Based on the comprehensive performance set of the bottom shell, the flow channel direction and cross-sectional shape are adjusted to generate an optimized flow channel planning scheme. Based on the optimized flow channel planning scheme, the working status data of the hydraulic oil tank is input into the bottom shell geometric model for digital simulation and virtual test platform verification to obtain the bottom shell performance parameter set; Based on the performance parameter set of the bottom shell, the geometric model of the bottom shell is lightweighted and the stress path is reconstructed to obtain the bottom shell structure. The strength, heat resistance and fatigue adaptability of the pre-set bottom shell material are evaluated to obtain the bottom shell material selection scheme. The comprehensive performance set of the bottom shell was verified based on the bottom shell structure and bottom shell material selection scheme, and a verification report and feedback information were obtained.

2. The design method for the bottom shell of a hydraulic oil tank in a new energy vehicle as described in claim 1, characterized in that: The specific steps for obtaining the functional requirements and constraints are as follows: The working status data of the hydraulic oil tank includes pressure timing data, oil temperature data, oil flow rate data, and vehicle operating condition data. Based on pressure time series data and oil flow data, the maximum bearing pressure, maximum flow rate and thermal load of the hydraulic oil tank are calculated, and the maximum bearing pressure, maximum flow rate and thermal load are compared with the corresponding change trends in the working status data of the hydraulic oil tank to obtain the functional requirements of the hydraulic oil tank. Based on the hydraulic fluid temperature data and the vehicle's operating conditions data, the minimum heat dissipation area and heat resistance temperature range of the hydraulic oil tank are calculated. The minimum heat dissipation area and heat resistance temperature range are then correlated with the temperature changes in the hydraulic oil tank's operating conditions data to obtain the constraints of the hydraulic oil tank.

3. The design method for the bottom shell of a hydraulic oil tank in a new energy vehicle as described in claim 2, characterized in that: The specific steps for generating the preliminary flow channel planning scheme are as follows: Based on the functional requirements and constraints of the hydraulic oil tank, the outer contour of the bottom shell, the starting position of the flow channel, the internal flow channel path and the position of key structures are determined, and the basic layout of the bottom shell space and flow channel path is obtained. Perform multi-objective optimization calculations on the basic layout of the bottom shell space and flow channel path to obtain the flow channel orientation and cross-sectional shape; Using a genetic algorithm, the flow channel orientation and cross-sectional shape are assigned positions and structural reinforcements are arranged to generate a preliminary flow channel planning scheme.

4. The design method for the bottom shell of a hydraulic oil tank in a new energy vehicle as described in claim 1, characterized in that: The specific steps for constructing the bottom shell geometric model are as follows. The functional layers of the bottom shell are determined based on the maximum bearing pressure, maximum flow rate, and thermal load of the hydraulic oil tank. Based on the functional layer, the outer contour of the bottom shell, the starting position of the flow channel, the flow channel path inside the bottom shell and the key structural positions are analyzed and optimized to determine the structural layer and material layer of the bottom shell. Based on the functional layer, structural layer, and material layer, a geometric model of the bottom shell is constructed using 3D modeling tools.

5. The design method for the bottom shell of a hydraulic oil tank in a new energy vehicle as described in claim 1, characterized in that: The specific steps for obtaining the comprehensive performance set of the bottom shell are as follows: The preliminary flow channel planning scheme is input into the bottom shell geometric model, and a three-dimensional fluid-thermal coupling simulation is performed on the bottom shell of the hydraulic oil tank to obtain the thermodynamic performance indicators. The structural stress analysis of the bottom shell geometric model was carried out using the finite element method to obtain the structural performance indicators; The thermal performance indicators and structural performance indicators are integrated into a comprehensive performance set for the bottom shell.

6. The design method for the bottom shell of a hydraulic oil tank in a new energy vehicle as described in claim 1, characterized in that: The specific steps for generating the optimized flow channel planning scheme are as follows: Thermal conduction analysis and topology optimization are performed on the overall performance set of the bottom shell to identify the weak points and optimization targets in the flow channel; Based on the weak points and optimization objectives, the flow channel direction and cross-sectional shape are adjusted to obtain the adjusted flow channel direction and cross-sectional shape. The adjusted flow channel orientation and cross-sectional shape are optimized using a multi-objective optimization algorithm to generate an optimized flow channel planning scheme.

7. The design method for the bottom shell of a hydraulic oil tank in a new energy vehicle as described in claim 1, characterized in that: The specific steps for obtaining the bottom shell performance parameter set are as follows: Based on the optimized flow channel planning scheme, the working status data of the hydraulic oil tank is input into the bottom shell geometric model to perform high-fidelity three-dimensional fluid-thermal coupling working condition simulation and obtain the working condition flow channel performance index. Structural response analysis of the bottom shell geometric model under measured loads was performed to obtain structural performance indicators under working conditions. The performance indicators of the flow channel and the structural performance indicators under working conditions are input into the virtual test platform for verification, and the performance parameter set of the bottom shell is obtained.

8. The design method for the bottom shell of a hydraulic oil tank in a new energy vehicle as described in claim 1, characterized in that: The specific steps to obtain the bottom shell structure are as follows. Based on the performance parameter set of the bottom shell, the bottom shell geometric model is lightweighted using a topology optimization algorithm to obtain an optimized bottom shell geometric model. The optimized bottom shell geometry model is reconstructed to obtain the structural reinforcement region and the bottom shell force path. The structural reinforcement area and the stress path of the bottom shell are adjusted to obtain the bottom shell structure.

9. The design method for the bottom shell of a hydraulic oil tank in a new energy vehicle as described in claim 1, characterized in that: The specific steps for obtaining the bottom shell material selection scheme are as follows: Based on the performance parameter set of the bottom shell, a strength analysis is performed on the structural performance index under working conditions to obtain the strength requirements for the selected bottom shell material; Thermal conduction analysis was performed on the performance indicators of the flow channel under operating conditions to obtain the heat resistance requirements of the bottom shell material; Based on pressure time series data and vehicle operating condition data, the fatigue life of the bottom shell material is estimated using the SN curve method, and the fatigue life requirement of the bottom shell material is obtained. Select a hydraulic tank bottom shell material that meets the strength, heat resistance, and fatigue life requirements from the pre-selected bottom shell materials to generate a bottom shell material selection scheme.

10. The design method for the bottom shell of a hydraulic oil tank in a new energy vehicle as described in claim 1, characterized in that: The specific steps to obtain the verification report and feedback information are as follows: Based on the bottom shell structure and bottom shell material selection scheme, the bottom shell geometric model is used to conduct preliminary performance simulation of the comprehensive performance set of the bottom shell, and the preliminary performance simulation results are obtained. The preliminary performance simulation results of the bottom shell were optimized and adjusted using a genetic algorithm to obtain an optimized bottom shell planning scheme. The optimized bottom shell planning scheme is input into the virtual test platform for long-term working condition verification, a verification report is generated, and the verification report is compared with the preset planning target to obtain improvement suggestions and feedback information.

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