A simulation calculation method for thermal management of a multi-system combined automobile

Abstract

The application belongs to the technical field of automobiles, and particularly relates to a thermal management simulation calculation method of a multi-system combined automobile. The application provides a new thermal management simulation calculation method of a multi-system combined automobile. The operation method of the calculation method is accurate, and the process of design simulation and calculation analysis is standardized, streamlined and platformized. The calculation method is based on the basic discipline principles of fluid mechanics, thermodynamics and combustion science as a theoretical basis, uses computer-aided analysis, and uses multi-system combined simulation technology to perform simulation calculation analysis on the thermal management system of the automobile.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of automobiles, and particularly relates to a thermal management simulation calculation method for a multi-system combined automobile. BACKGROUND

[0002] In the automobile industry, simulation means based on CAE (computer aided engineering) analysis has been widely applied to product research and development of major automobile manufacturers and related part suppliers, and vehicle thermal management simulation analysis including cooling system, lubrication system, air conditioning system, thermodynamic analysis, member cabin inner and outer flow field and temperature field is analyzed independently, and multi-system combined simulation cannot be performed. Independent simulation of numerous systems, long setting time of boundary conditions, numerous boundary input conditions need to be assumed, complex geometries with transient boundary characteristics cannot be accurately simulated, complex fluid systems cannot be accurately analyzed in real time, and boundary conditions, data quality and simulation results cannot be improved in real time, directly and uniformly among systems, which makes the simulation accuracy, accuracy and authenticity of the whole vehicle thermal management system low. SUMMARY

[0003] In view of the above problems, the application provides a new thermal management simulation calculation method for a multi-system combined automobile.

[0004] The specific technical scheme of the application is as follows:

[0005] The application provides a thermal management simulation calculation method for a multi-system combined automobile, and the calculation method comprises the following steps:

[0006] S1: extracting a water jacket flow model;

[0007] S2: creating an engine cylinder body thermal model, wherein the engine cylinder body thermal model comprises a parameterized finite element cylinder model and a thermal mass model of a cylinder block and a cylinder head;

[0008] S3: assembling the water jacket flow model, the finite element cylinder model and the thermal mass model;

[0009] S4: calibrating heat transfer and pressure difference of the assembled model, connecting each thermal related model of the engine, and connecting the engine thermal distribution model and the engine thermodynamic model;

[0010] S5: starting simulation running, and outputting heat discharge of a test working condition point.

[0011] The application has the following beneficial effects:

[0012] The application provides a new automobile multi-system combined thermal management simulation calculation method, which is accurate in operation method, and is standardized, streamlined and platformized in design simulation and calculation analysis process, and is based on basic disciplines such as fluid mechanics, thermodynamics and combustion science as a theoretical basis, and uses computer-aided analysis and multi-system combined simulation technology to simulate and analyze the automobile thermal management system. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 A flow chart of the automobile multi-system combined thermal management simulation calculation method in the application is shown in the figure.

[0014] Figure 2 A flow chart of step S1 in the application is shown in the figure.

[0015] Figure 3 A structure diagram of the 1D discrete water jacket model in the application is shown in the figure.

[0016] Figure 4 A flow chart of steps S21-S23 in the application is shown in the figure.

[0017] Figure 5 A flow chart of steps S200-S201 in the application is shown in the figure. DETAILED DESCRIPTION

[0018] The application will be further described below in combination with the drawings and examples, and the following examples are only used to explain the inventive content of the application, and cannot be used to limit the protection scope of the application.

[0019] The application provides an automobile multi-system combined thermal management simulation calculation method, as shown in the figure, which comprises the following steps: Figure 1

[0020] S1: extracting a water jacket flow model;

[0021] S2: creating an engine cylinder block thermal model, wherein the engine cylinder block thermal model comprises a parameterized finite element cylinder model and a thermal mass model of a cylinder block and a cylinder head;

[0022] S3: assembling the water jacket flow model, the finite element cylinder model and the thermal mass model;

[0023] S4: calibrating heat transfer and pressure difference for the assembled model, connecting each thermal related model of the engine, and connecting an engine thermal distribution model and an engine thermodynamic model;

[0024] S5: starting simulation running, and outputting heat release of a test working condition point. The heat release of an untested working condition point, transient warm-up working condition analysis in a vehicle driving cycle and the like can be predicted.

[0025] ​The embodiment relates to a CAE (Computer Aided Engineering)-based whole vehicle multi-system joint thermal management simulation calculation method.

[0026] The embodiment investigates the mutual influence of certain special elements and the whole system working performance during thermal analysis. The method has the following advantages:

[0027] 1. The reliability of various assumptions made for simulation is higher;

[0028] 2. The thermal flow field of a complex geometric body with transient boundary characteristics can be accurately simulated;

[0029] 3. The working characteristics of key components and the coupling characteristics between the components and the system can be simulated;

[0030] 4. The errors of boundary condition assumptions and user input parameters are reduced, the setting time of boundary conditions is reduced, the data quality is improved, the boundary conditions are more accurate, and the system characteristic simulation result is more accurate;

[0031] 5. The method is beneficial to timely finding problems, improving problems and innovative research in each stage of product research and development;

[0032] 6. The research and development time and cost are reduced.

[0033] In the embodiment, the CAE simulation software can be jointly simulated by using Flowmaster, three-dimensional CFD (Flunt or Star-CCM+), GT-power, AVL-Boost, Cruise, ANSYS and the like. The sub-function module software in GT-SUITE can also be jointly simulated on the same platform. The systems that can be jointly simulated include an engine thermodynamic model, a whole vehicle model, a cylinder thermal mass model, a cooling system, a lubricating system, an air side system, a passenger cabin system, an air conditioning system, a friction model, an ECU control system and the like.

[0034] The embodiment is described in detail below by taking a typical vehicle as an example. Input conditions: environment temperature 38 DEG C, whole vehicle working condition high speed 160 km / h-5 gear, 8% climbing 45 km / h-2 gear. According to comprehensive analysis of power economy, engine thermal flow distribution, coolant temperature and the like, a whole vehicle power matching control scheme is formulated.

[0035] As Figure 2 shown, the step S1 in the embodiment includes the following steps:

[0036] S11: converting the water jacket CAD model to a corresponding format, extracting the internal flow volume and converting the entity;

[0037] S12: obtaining the thermal solving rate with a rough discretization of the entity, calibrating the volume and heat transfer area;

[0038] S13: minimizing the flow loss inside the water jacket, applying a characteristic pressure drop curve at each outlet to obtain a one-dimensional discrete water jacket model.

[0039] In the embodiment, after converting the water jacket CAD model to a corresponding format, extracting the internal flow volume, i.e. the flow model of the water jacket, converting the entity and measuring the size, the thermal solving rate is obtained with a rough discretization, the volume and heat transfer area are calibrated, the flow loss inside the water jacket is minimized, and a characteristic pressure drop curve is applied at each outlet to maintain the correct flow distribution to the external connection branches. A one-dimensional discrete water jacket model is obtained, as Figure 3 shown.

[0040] In the step S2 in the embodiment, the parameterized finite element cylinder model is shared by the engine and the cooling system, and the structural parameters include the cylinder head plane thickness, the cylinder liner thickness, the cylinder length, the water jacket upper surface distance, the water jacket lower surface distance and the water jacket angle. The parameterized finite element cylinder is shared by the engine and the cooling system model, which is beneficial to the sharing of the model between different departments. The structural parameter values can be measured, such as the cylinder head plane thickness, the cylinder liner thickness, the cylinder length, the water jacket upper surface distance, the water jacket lower surface distance, etc.

[0041] As Figure 4 shown, the step S2 in the embodiment includes the following steps:

[0042] S21: cutting the converted cylinder block and head thermal mass as a section with the boundaries of the four cylinders of the engine as the section;

[0043] S22: applying the environmental convection boundary on the surface of the cut thermal mass, creating the connection nodes and boundary conditions of the thermal mass;

[0044] S23: checking the number of thermal masses and the number of interfaces, creating the heat transfer connection between the thermal masses in contact, and exporting the one-dimensional cylinder block and head thermal mass model.

[0045] The heat mass model of the cylinder block and head is created in this embodiment. The boundaries of the four cylinders are taken as the cutting surface to cut and transform the heat mass of the cylinder block and head. The convective boundary of the environment is applied to the surface of the cut heat mass, and the connecting nodes and boundary conditions of the heat mass are automatically created. The cylinder block and head are marked to obtain the heat transfer area of the cooling liquid and lubricating oil, and the created nodes can also be connected with the boundary conditions or flow volume.

[0046] The number of heat masses and the number of interfaces are detected, and the heat transfer connection between the heat masses in contact is automatically created, and the 1D heat mass model of the cylinder block and head is derived.

[0047] As shown in Figure 5 , the step S2 in this embodiment further includes the following steps:

[0048] S200: Import the CAD template of the engine into the structure of the finite element grid, and create the surface interface of each heat mass component;

[0049] S201: Import the template into the engine cylinder block structure model to obtain the engine cylinder block heat model.

[0050] The steps of creating the finite element cylinder model and the heat mass model of the cylinder block and head in this embodiment can be combined to create the engine cylinder block heat model. The CAD template of the engine is imported into the structure of the finite element grid, the surface interface of each heat mass component is created and defined, and then the template is imported into the customized engine cylinder block structure model.

[0051] The step S3 in this embodiment includes the following steps:

[0052] The heat convection and heat conduction coefficients of the 1D discrete water jacket model and the engine cylinder block heat model are connected, and the cross-sectional area of each heat transfer part is calibrated.

[0053] When assembling the water jacket, cylinder and heat mass model, most of the nodes of the heat mass are automatically generated, and some additional heat mass nodes of the cylinder head and cylinder block need to be created. At the same time, the heat convection and heat conduction coefficients in the discrete 1D water jacket model and the engine cylinder block heat model are connected. The cross-sectional area of each heat transfer part is calibrated (the method in the engine cylinder block heat model creation step can be omitted because the area is automatically generated). The lubricating oil volume of the cylinder block and head is increased, and the convective heat transfer coefficient is generally taken as 400 W / m2K

[0054] When calibrating the heat transfer and pressure difference of the model in step S4 in this embodiment, the heat transfer coefficient is based on the calculation result of CFD, the heat transfer area is based on the CAD data, and the pressure difference boundary condition of the inlet and outlet is applied based on the test result.

[0055] The flow field of three-dimensional flow cannot be obtained in one-dimensional model, and the simultaneous three-dimensional flow effect will affect the calculation of pressure drop and heat transfer, so the model is calibrated for heat transfer and pressure difference; when the model is calibrated for heat transfer and pressure difference: a. The heat transfer coefficient is based on the CFD calculation result, and the heat transfer area comes from the CAD data. b. The inlet and outlet pressure difference boundary conditions are applied based on the test results. c. If some data is not available, the calibration can be assumed within the experience range, and then the calculation results are continuously checked and optimized.

[0056] The step S4 of connecting each thermal related model of the engine in this embodiment includes the following steps:

[0057] The finite element cylinder model is connected to the gas boundary, the cooling system is connected by the water jacket (i.e. the water jacket flow model), the radiator is connected to the air side ID analysis model, and the oil circuit and the lubrication system are connected. After the relevant parameter calibration is completed, the engine thermal distribution model can be used for system coupling. The finite element model is connected to the gas boundary (because the finite element cylinder has been assembled and connected with the thermal mass model and the water jacket flow model, therefore,). The cooling system is connected by the water jacket, the radiator is connected to the air side 1D analysis model, and the oil circuit is connected to the lubrication system; after each model is established, they are combined together with related channels or reference to each other's system parameters to produce mutual influence.

[0058] The step S4 of connecting the engine thermal distribution model and the engine thermodynamic model in this embodiment includes:

[0059] The engine thermal distribution model is connected with the engine thermodynamic model through the combustion boundary in the engine thermodynamic model.

[0060] In this embodiment, the engine thermal distribution model is connected with the engine thermodynamic model through the combustion boundary in the engine thermodynamic model. At the same time, the opening time of the valve in the engine thermal distribution model is adjusted to correspond to the engine thermodynamic model; at the same time, the engine thermal distribution model is a machine body, which is installed to the heat transfer part after being meshed, and the heat transfer coefficient and the like are calibrated, at this time, it becomes a heat transfer model, i.e. the connected water jacket flow model and the like. In this step, each model above is connected with the engine thermodynamic model.

[0061] After the engine thermal distribution model and the engine thermodynamic model are connected in the step S4 in this embodiment, the friction model and the loop model are constructed, and the friction model, the loop model are connected with the engine thermal distribution model and the engine thermodynamic model;

[0062] The friction model is calibrated by parameter data, and the parameter data is obtained by doing reverse drag test and gradually removing parts for friction test under different speeds and water temperatures;

[0063] The loop model includes a vehicle model and an ECU vehicle module.

[0064] The added friction loop, the parameters in the friction model are obtained by data from different speed and water temperature to do the test, gradually remove the parts of the parts of the friction test, etc. Test method to calibrate the friction model. If there is no test condition, the experience correction model or Chen-Flynn equation method can be used to calibrate the friction model;

[0065] Increase the remaining required loop model, when simulating transient conditions, mainly including vehicle model and ECU control module, etc., so as to realize the rapid data interaction between systems and the sharing of model data between different departments.

[0066] The connection of each model appearing in the embodiment can also be selected according to the demand of only a few systems or models that are more concerned about the relevant projects, at which time other systems can be simplified or omitted.

[0067] According to the calculation of the multi-system joint thermal simulation model, the highest temperature of the cooling liquid in the original scheme is 95℃ in high-speed working condition, and the highest temperature of the cooling liquid is 112℃ in climbing working condition, which do not meet the requirements of the cooling system. The improved scheme considers reducing the transmission ratio according to the experience of matching the power economy of the vehicle. The calculation results show that the highest temperature of the cooling liquid is 92℃ in high-speed working condition, and the highest temperature of the cooling liquid is 108℃ in climbing working condition, which is lower than 110℃, and meets the requirements of the cooling system. Finally, the system is analyzed and evaluated, and improvement suggestions are made, and the vehicle power matching control scheme is developed, and the analysis report is issued.

[0068] Although this specification contains many specific implementation details, these should not be construed as limitations on the scope or scope of what can be claimed, but as descriptions of features that can be particularized in specific implementations of particular inventions. Certain features described in this specification in the context of separate implementations can also be implemented in combination with a single implementation. Conversely, various features described in the context of a single implementation can also be implemented independently of one another in multiple implementations, or in any suitable subcombination. In addition, although the above can describe features as being combined in a combination and even initially as claimed as such, one or more features from a combination of claims can in some cases be removed from the combination and the combination of claims can be directed to a subcombination or variation of a subcombination.

[0069] In certain cases, multitasking and parallel processing can be advantageous. In addition, the separation of various system modules and components in the above-described implementations should not be understood as requiring such separation in all implementations.

[0070] Particular implementations of the subject matter have been described. Other implementations are within the scope of the following claims. For example, the acts recited in the claims can be performed in a different order and still achieve desirable results. As one example, the processes described in the accompanying figures can not require the particular order shown, or sequential order, to achieve desirable results. In certain implementations, multitasking and parallel processing can be advantageous.

Claims

1. A simulation calculation method for thermal management of multiple automotive systems, characterized in that, The calculation method includes the following steps: S1: Extract the water jacket flow model; S2: Create an engine block thermal model, which includes a parameterized finite element cylinder model and a thermal mass model of the cylinder block and cylinder head. S3: Assembly water jacket flow model, finite element cylinder model and thermal mass model; S4: Perform heat transfer and differential pressure calibration on the assembled model, connect the various thermally related models of the engine, and connect the engine thermal distribution model and the engine thermodynamic model. S5: Start the simulation and output the heat release at the test conditions. Step S1 includes the following steps: S11: Convert the water jacket CAD model to the corresponding format, extract the internal flow volume and convert it into a solid; S12: Obtain the thermal solution rate by using a coarse discretization of the entity, and calibrate the volume and heat transfer area; S13: Minimize the flow loss inside the water jacket by applying a characteristic pressure drop curve to each outlet to obtain a one-dimensional discrete water jacket model.

2. The automotive multi-system combined thermal management simulation calculation method as described in claim 1, characterized in that, The parameterized finite element cylinder model in step S2 is used for both the engine and the cooling system. The structural parameters include cylinder head plane thickness, cylinder liner thickness, cylinder length, distance between the upper and lower surfaces of the water jacket, and water jacket angle.

3. The automotive multi-system combined thermal management simulation calculation method as described in claim 1, characterized in that, Step S2, creating the thermal mass model of the cylinder block and cylinder head, includes the following steps: S21: Using the boundaries of each of the four cylinders of the engine as sectional surfaces, cut and transform the hot mass of the cylinder block and cylinder head; S22: Apply the convective boundary of the environment to the surface of the cut thermal mass, creating the connection nodes and boundary conditions of the thermal mass; S23: Check the number of thermal masses and the number of interfaces, create heat transfer connections between contacting thermal masses, and export a one-dimensional thermal mass model of the cylinder block and cylinder head.

4. The automotive multi-system combined thermal management simulation calculation method as described in claim 1, characterized in that, Step S2 also includes the following steps: S200: Import the engine's CAD template and convert it into a finite element mesh structure, and create the surface interfaces for each thermal mass component; S201: Import the template into the engine block structure model to obtain the engine block thermal model.

5. The automotive multi-system combined thermal management simulation calculation method as described in claim 1, characterized in that, Step S3 includes the following steps: Connect the thermal convection and thermal conductivity coefficients of the one-dimensional discrete water jacket model and the engine cylinder block thermal model, and calibrate the cross-sectional area of ​​each heat transfer part.

6. The automotive multi-system combined thermal management simulation calculation method as described in claim 1, characterized in that, In step S4, when calibrating the model for heat transfer and differential pressure, the heat transfer coefficient is based on the CFD calculation results, the heat transfer area is based on CAD data, and differential pressure boundary conditions at the inlet and outlet are applied based on the test results.

7. The automotive multi-system combined thermal management simulation calculation method as described in claim 1, characterized in that, Step S4, which connects the various thermally related models of the engine, includes the following steps: Connect the finite element cylinder model and the gas boundary, use a water jacket to connect the cooling system, connect the radiator to the air-side ID analysis model, and connect the oil circuit and lubrication system.

8. The automotive multi-system combined thermal management simulation calculation method as described in claim 1, characterized in that, Step S4, connecting the engine thermal distribution model and the engine thermodynamic model, includes: The engine heat distribution model is connected to the engine thermodynamic model by using the combustion boundary in the engine thermodynamic model.

9. The automotive multi-system combined thermal management simulation calculation method as described in claim 1, characterized in that, In step S4, after connecting the engine thermal distribution model and the engine thermodynamic model, a friction model and a loop model are constructed, and the friction model and the loop model are connected to the engine thermal distribution model and the engine thermodynamic model. The friction model is calibrated using parameter data, which is obtained by performing a dragging test at different speeds and water temperatures, and by gradually disassembling parts to perform friction tests. The circuit model includes a vehicle model and an ECU vehicle module.

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