Engine air passage optimization method, device, equipment and medium

Abstract

The invention relates to the technical field of engine design, and discloses an engine airway optimization method, device and equipment and a medium. The method comprises the steps that a three-dimensional model of an air cylinder of an engine is obtained; dividing grids for the cylinder three-dimensional model, and adopting dynamic grids for the piston position and the valve position to obtain a cylinder fluid simulation model; dynamic boundary conditions of gas in the cylinder are obtained; determining motion data for controlling the piston position and the valve position; according to the dynamic boundary condition and the motion data, performing simulation calculation on the cylinder fluid simulation model to obtain a swirl rate and a flow coefficient; and adjusting the shape of the three-dimensional model of the cylinder according to the swirl ratio and the flow coefficient, and returning to the step of dividing the grids for the three-dimensional model of the cylinder. According to the invention, the accuracy and efficiency of airway optimization are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of engine design, and in particular to an engine airway optimization method, device, equipment and medium. Background Art

[0002] The airway flow characteristics of the engine play an important role in the formation of diesel engine oil-gas mixture, combustion, charge movement, etc. Its quality directly affects the technical indicators of the diesel engine such as power, fuel consumption, emissions and noise. The traditional airway design method adopts empirical design, and adjusts the geometric shape of the intake duct through repeated tests on the steady flow test bench after multiple corrections to obtain high intake flow and appropriate intake swirl ratio. The complex spiral airway shape has a great influence on the swirl ratio and flow coefficient. It is completely dependent on the steady flow test of the intake duct to obtain good airway flow characteristics. It requires a large number of tests to repeatedly modify the airway shape. In addition, the steady flow test can only obtain the average value of the parameters of the airway inlet and outlet from the overall perspective, and cannot directly obtain the swirl ratio and flow coefficient. Therefore, the airway shape is adjusted according to the experimental method, resulting in inaccurate adjustment results and low optimization efficiency. The design of modern diesel engine air ducts widely adopts a method that combines fluid mechanics three-dimensional simulation with steady flow tests. Through the simulation and analysis of air duct flow characteristics, the macroscopic influence of the intake duct, valve and cylinder structural parameters and their relative positions on the flow is understood, providing a basis for air duct design and combustion system matching. However, the commonly used fluid mechanics three-dimensional simulation method is not accurate enough for the calculation of swirl ratio and flow coefficient, resulting in inaccurate engine air duct optimization, which in turn affects the engine air duct optimization efficiency. Summary of the invention

[0003] In view of this, the present invention provides an engine air duct optimization method, device, equipment and medium to solve the problem of low efficiency of engine air duct optimization.

[0004] In a first aspect, the present invention provides an engine air duct optimization method, the method comprising: obtaining a three-dimensional model of the engine cylinder; dividing the three-dimensional cylinder model into grids, and using dynamic grids for the piston position and the valve position to obtain a cylinder fluid simulation model; obtaining the dynamic boundary conditions of the gas in the cylinder; determining motion data for controlling the piston position and the valve position; simulating the cylinder fluid simulation model according to the dynamic boundary conditions of the gas in the cylinder and the motion data to obtain a swirl ratio and a flow coefficient; adjusting the shape of the three-dimensional cylinder model according to the swirl ratio and the flow coefficient, and returning to the step of dividing the cylinder three-dimensional model into grids.

[0005] In some optional embodiments, the three-dimensional model of the cylinder is meshed, and dynamic meshes are used for the piston position and the valve position to obtain a cylinder fluid simulation model, including: dividing the three-dimensional model of the cylinder with a cutting body mesh, and refining the mesh at small surfaces or gaps; setting the meshes of the piston position and the valve position as dynamic meshes; stretching and extending the intake and exhaust duct parts; specifying the fluid area and solid area of ​​the cylinder to obtain the cylinder fluid simulation model.

[0006] In some optional embodiments, the obtaining of the dynamic boundary conditions of the gas in the cylinder includes: collecting boundary data through a steady flow test, wherein the boundary data is data on changes in the temperature and pressure of the gas in the cylinder with the crankshaft angle; and processing the boundary data into a boundary table as the dynamic boundary condition.

[0007] In some optional embodiments, the determination of motion data for controlling the piston position and the valve position includes: setting a connecting rod length sequence, the connecting rod length sequence including multiple connecting rod length values, each connecting rod length value in the connecting rod length sequence being used to represent the displacement of the connecting rod as the crankshaft angle changes, and the connecting rod length sequence being used as motion data for controlling the piston position; obtaining a valve lift curve that changes with the crankshaft angle, and processing the valve lift curve into a valve lift table as motion data for controlling the valve position.

[0008] In some optional implementations, processing the valve lift curve into a valve lift table includes: acquiring a valve clearance parameter; and subtracting the valve clearance parameter from data in the valve lift table to obtain a processed valve lift table.

[0009] In some optional embodiments, the simulation calculation of the cylinder fluid simulation model is performed according to the dynamic boundary conditions of the gas in the cylinder and the motion data, including: defining a solution step and a solution time, wherein the solution step represents the time for each degree of crankshaft angle rotation, and the solution time represents the simulation duration; defining a first calling function and a second calling function, wherein the first calling function is used to extract boundary data from the boundary table according to the solution step, and the second calling function is used to extract valve lift data from the valve lift table according to the solution step; defining an initial crankshaft angle of the cylinder fluid simulation model; executing the first calling function and the second calling function according to the solution step and the initial crankshaft angle, and extracting the boundary data and the valve lift data of each solution step in turn; extracting the connecting rod length value corresponding to each solution step from the connecting rod length sequence; importing the boundary data, the valve lift data and the connecting rod length value corresponding to each solution step as input data in turn into the cylinder fluid simulation model, and executing the software algorithm within the solution time to obtain the swirl ratio and the flow coefficient.

[0010] In some optional embodiments, the shape of the cylinder three-dimensional model is adjusted according to the swirl ratio and the flow coefficient, including: determining whether the swirl ratio is greater than or equal to a preset swirl ratio threshold, and determining whether the flow coefficient is greater than or equal to a preset flow threshold; if the swirl ratio is less than the preset swirl ratio threshold, or the flow coefficient is less than the preset flow threshold, adjusting the shape of the intake port in the cylinder three-dimensional model; if the swirl ratio is greater than or equal to the preset swirl ratio threshold, and the flow coefficient is greater than or equal to the preset flow threshold, outputting the current cylinder three-dimensional model.

[0011] In a second aspect, the present invention provides an engine air duct optimization device, which includes: a three-dimensional model acquisition module for acquiring a three-dimensional model of a cylinder of an engine; a simulation model generation module for gridding the three-dimensional model of the cylinder, and using dynamic grids for the piston position and the valve position to obtain a cylinder fluid simulation model; a boundary condition setting module for obtaining the dynamic boundary conditions of the gas in the cylinder; a motion law acquisition module for determining motion data for controlling the piston position and the valve position; a simulation calculation module for performing simulation calculations on the cylinder fluid simulation model based on the dynamic boundary conditions of the gas in the cylinder and the motion data to obtain a swirl ratio and a flow coefficient; an air duct analysis module for adjusting the shape of the three-dimensional model of the cylinder based on the swirl ratio and the flow coefficient, and returning to the step of gridding the three-dimensional model of the cylinder.

[0012] In a third aspect, the present invention provides a computer device, comprising: a memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, and the processor executing the method of the first aspect or any corresponding embodiment thereof by executing the computer instructions.

[0013] In a fourth aspect, the present invention provides a computer-readable storage medium having computer instructions stored thereon, the computer instructions being used to cause a computer to execute the method of the first aspect or any corresponding embodiment thereof.

[0014] The technical solution provided by the present invention has the following advantages:

[0015] By using dynamic grids for the piston and valve positions, and considering the dynamic boundary conditions and motion data of the gas in the cylinder that changes with the crankshaft angle, the movement of the piston and valve is controlled during the simulation calculation. At the same time, the temperature and pressure changes of the gas in the cylinder are also introduced into the calculation algorithm of the software through the dynamic boundary conditions, making the simulation closer to the real working principle of the engine cylinder, so as to calculate a more accurate swirl ratio and flow coefficient. Then, the shape of the cylinder three-dimensional model is adjusted according to the calculated swirl ratio and flow coefficient, which can provide an accurate adjustment basis, thereby improving the accuracy of the adjustment of the cylinder three-dimensional model, and then improving the optimization efficiency of the engine airway. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 is a flow chart of an engine airway optimization method according to an embodiment of the present invention;

[0018] Figure 2 is a schematic diagram of the structure of a three-dimensional model of a cylinder according to an embodiment of the present invention;

[0019] Figure 3 is a data schematic diagram of dynamic boundary conditions according to an embodiment of the present invention;

[0020] Figure 4 is a schematic diagram of a valve lift curve according to an embodiment of the present invention;

[0021] Figure 5 is a structural schematic diagram of an engine airway optimization device according to an embodiment of the present invention;

[0022] Figure 6 It is a schematic diagram of the hardware structure of a computer device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0024] The airway flow characteristics of the engine play an important role in the formation of diesel engine oil-gas mixture, combustion, charge movement, etc. Its quality directly affects the technical indicators of the diesel engine such as power, fuel consumption, emissions and noise. The traditional airway design method adopts empirical design, repeatedly tests the cylinder on the steady flow test bench, and adjusts the geometric shape of the intake duct after multiple corrections to obtain a high intake flow and a suitable intake swirl ratio. The complex spiral airway shape has a great influence on the swirl ratio and flow coefficient. It is completely dependent on the steady flow test of the intake duct to obtain good airway flow characteristics. It requires a large number of tests to repeatedly modify the airway shape, which is costly. In addition, the steady flow test can only obtain the average value of the parameters of the airway inlet and outlet from the overall perspective, and cannot directly obtain the swirl ratio and flow coefficient. Therefore, the airway shape is adjusted according to the experimental method, resulting in inaccurate adjustment results and low optimization efficiency.

[0025] The design of modern diesel engine air ducts widely adopts a method that combines fluid mechanics three-dimensional simulation with steady flow tests. By simulating and analyzing the air duct flow characteristics, the macroscopic influence of the intake duct, valve, cylinder structural parameters and their relative positions on the flow is understood, providing a basis for air duct design. However, the commonly used fluid mechanics three-dimensional simulation method is not accurate enough for the calculation of swirl ratio and flow coefficient, resulting in inaccurate engine air duct optimization, which in turn affects the engine air duct optimization efficiency.

[0026] At present, some commonly used simulation methods first create a three-dimensional model of the engine intake structure, and then perform fluid simulation analysis on the three-dimensional model to obtain theoretical flow coefficient, theoretical swirl ratio, theoretical tumble ratio and other results. This process is generally implemented using steady-state calculations with an interval of 2mm or 1mm from the minimum lift to the maximum lift.

[0027] The valve lift in an intake compression cycle of the engine will change with the crankshaft angle. If the flow rate and swirl ratio under each valve lift are calculated, the amount of calculation will be very large. In addition, the valve lift change at each crankshaft angle is relatively small (for example, 0.01mm or less), and the simulation model accuracy cannot be accurately described. The commonly used simulation method uses a steady-state calculation method to simplify the calculation. This method uses a slightly larger interval to calculate the flow coefficient and swirl ratio under a few valve lifts (for example, 2mm, 4mm, 6mm, ..., 14mm), without considering the actual movement of the valve piston, and the influence of the exhaust port, etc., and then interpolates between the flow coefficients and swirl ratios calculated at these large intervals to obtain the flow coefficients and swirl ratios with valve lift.

[0028] This method does not take into account the changes in the pressure and temperature of the gas in each cylinder with the crankshaft angle, but uses fixed values ​​instead. It also does not consider the impact of the movement of the piston on the vortex in the cylinder. In addition, it only calculates a few fixed lifts and then performs interpolation solutions, resulting in low overall simulation accuracy. As a result, the calculated flow coefficient and swirl ratio have low accuracy, which affects the engine airway optimization.

[0029] According to an embodiment of the present invention, an embodiment of an engine air duct optimization method is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0030] In this embodiment, a method for optimizing an engine airway is provided. Figure 1 is a flow chart of an engine airway optimization method according to an embodiment of the present invention, the flow chart comprising the following steps:

[0031] Step S101, obtaining a three-dimensional model of a cylinder of an engine.

[0032] Specifically, the present invention provides a transient simulation method for vortex in an engine cylinder, so that the simulation process is closer to the actual working principle of the engine cylinder, so as to improve the accuracy of the vortex ratio and flow coefficient calculated subsequently. First, a three-dimensional model of the cylinder of the engine is obtained. In this embodiment, the three-dimensional model of the cylinder can be a CAD model including the intake duct, exhaust duct, combustion chamber, intake valve, exhaust valve, cylinder liner, and piston of a diesel engine. This embodiment is only used as an example and is not limited to this. Models generated by other three-dimensional mapping software can also be used.

[0033] Step S102, meshing the three-dimensional model of the cylinder, and using dynamic meshes for the piston position and valve position to obtain a cylinder fluid simulation model.

[0034] Specifically, Figure 2 As shown in the figure, in order to improve the accuracy and efficiency of the subsequent calculation results of the vortex and turbulent momentum distribution in the cylinder, a cylinder fluid simulation (Computational Fluid Dynamics, CFD) model corresponding to the cylinder three-dimensional model is created. When creating this model, it is necessary to use dynamic mesh processing for the piston position and valve position, so that the specific position of the piston and valve can be controlled in the subsequent finite element simulation calculation process. By controlling the valve position, it is possible to avoid calculating the flow coefficient and swirl ratio under only a few valve lifts, and there is no need to interpolate in a larger valve lift interval, so that the flow coefficient and swirl ratio calculated for each valve position have high accuracy. By controlling the piston, the movement of the piston in the Z direction is simulated, and the influence of the movement of the piston on the vortex in the cylinder is fully considered, thereby significantly improving the accuracy of the calculated swirl ratio.

[0035] Step S103, obtaining the dynamic boundary conditions of the gas in the cylinder.

[0036] Step S104, determining motion data for controlling the piston position and the valve position.

[0037] Specifically, the embodiment of the present invention also obtains two dynamic data, namely dynamic boundary conditions and motion data, wherein the dynamic boundary conditions are used to describe the temperature, pressure and other conditions of the gas in various parts of the cylinder that change with the crankshaft angle, thereby describing the working environment in the cylinder. The motion data refers to the displacement of the valve and piston that changes with the crankshaft angle; for the valve, the motion data refers to the valve lift curve, which is used to indicate the specific lift of the valve at different crankshaft angles; for the piston, it refers to the control parameters that can affect the specific position of the piston in the cylinder at different crankshaft angles.

[0038] Step S105, performing simulation calculation on the cylinder fluid simulation model according to the dynamic boundary conditions and motion data of the gas in the cylinder to obtain the swirl ratio and flow coefficient;

[0039] Step S106, adjusting the shape of the three-dimensional model of the cylinder according to the swirl ratio and the flow coefficient, and returning to the step of dividing the three-dimensional model of the cylinder into grids.

[0040] Specifically, by using dynamic grids for the piston position and valve position, and considering the dynamic boundary conditions and motion data that change with the crankshaft angle, the motion position of the piston and valve is controlled during the simulation calculation. At the same time, the temperature change and pressure change of the gas in the cylinder are also introduced into the calculation algorithm of the software through the dynamic boundary conditions, making the simulation closer to the real working principle of the engine cylinder, so as to calculate a more accurate swirl ratio and flow coefficient. Then, the shape of the cylinder three-dimensional model is adjusted according to the calculated swirl ratio and flow coefficient, which can provide an accurate basis for adjustment. Finally, according to the calculated swirl ratio and flow coefficient, it is possible to accurately judge whether the performance of the cylinder has reached the indicators required by the user, and adjust the shape of the cylinder three-dimensional model when the indicators are not reached. Repeating the simulation can improve the accuracy of the adjustment of the cylinder three-dimensional model, thereby improving the optimization efficiency of the engine airway.

[0041] In some optional implementations, the above step S102 includes:

[0042] Step a1, dividing the cylinder three-dimensional model by using a cutting body grid, and refining the grid at small surfaces or gaps;

[0043] Step a2, setting the grids of the piston position and the valve position to dynamic grids;

[0044] Step a3, stretching and extending the air inlet and exhaust ducts;

[0045] Step a4, specifying the fluid region and solid region of the cylinder to obtain a cylinder fluid simulation model.

[0046] Specifically, the embodiment of the present invention creates a cylinder fluid simulation model for finite element fluid analysis based on the three-dimensional model of the cylinder, and first needs to perform grid division. In this embodiment, the three-dimensional model of the cylinder is divided by a cut volume grid. Finite element grids are mainly divided into two categories: cut volume grids and polyhedron grids, where the cut volume grid is used to describe a set of discrete points in a plane or space. Each unit in the cut volume grid is a convex polyhedron segmented by a point set, and it has the following characteristics: 1. The cut volume grid is a discretized surface model, which is composed of a grid composed of a series of points, lines, surfaces and body elements; 2. Each unit in the cut volume grid is a convex polyhedron segmented by a point set, and each convex polyhedron corresponds to a Fan lattice of discrete points one by one; 3. The geometric information in the cut volume grid is described by a set of points and the structural relationship between them, and each discrete point represents a vertex on the model surface; 4. The cut volume grid has good deformability and adaptability, and can be used for applications such as pixelation, morphological analysis and volume rendering. In computer graphics, cut volume meshes can be used to discretize volumes and simplify simulation problems into mathematical models based on geometric units. They can be used to simulate flow fields, acoustic fields, heat transfer, deformation, and other problems, thereby improving the accuracy of cylinder fluid simulation.

[0047] At the same time, this embodiment refines the mesh on small surfaces or gaps to ensure that the model is not distorted as much as possible, which can improve the accuracy of software solution calculations.

[0048] Then, a dynamic mesh design is used for the grids of the piston position and valve position, so that the control piston can be simulated during the cylinder intake and compression strokes, as well as the position changes of the valves, making the cylinder's working process more realistic.

[0049] In addition, this embodiment also partially stretches and extends the intake duct and the exhaust duct (for example, 50 mm), which can prevent the problem of gas backflow in the air duct.

[0050] Since there is free flow of air (fluid) and movement of valve (solid) during the simulation analysis, the present embodiment also needs to set the physical continuum of fluid and solid separately. That is, the physical property parameters of gas and solid are set separately. After the setting is completed, it is possible to specify which part is the fluid area and which part is the solid area in the three-dimensional software, so as to facilitate the recognition of the simulation software and improve the accuracy of subsequent simulation calculations.

[0051] Furthermore, in some optional implementations, the simulated fluid uses a multi-component mixed gas of oxygen and nitrogen that is closer to reality, thereby improving the accuracy of the fluid simulation.

[0052] In some optional implementations, the above step S103 includes:

[0053] Step b1, collecting boundary data through a steady flow test, the boundary data being data on changes in the temperature and pressure of the gas in the cylinder with the crankshaft angle;

[0054] Step b2, processing the boundary data into a boundary table as a dynamic boundary condition.

[0055] Specifically, in order to improve the accuracy of dynamic boundary conditions, the embodiment of the present invention is based on real data, and collects data on the change of temperature and pressure in the cylinder with the crankshaft angle on the test bench through a steady flow test, so as to obtain the following Figure 3 The boundary data is shown. Since the boundary data is in the form of a curve, it is not convenient to use it directly in the simulation. In the embodiment of the present invention, the temperature and pressure of the cylinder liner, the intake duct, the exhaust duct and other positions are processed into a boundary table. The data of each angle is generated in a separate table and named separately, which is used to store the temperature and pressure at a crankshaft angle.

[0056] Later, when writing function code relationships in the fluid simulation software, the pressure and temperature results corresponding to the crankshaft angle can be called in the form of a table, which is equivalent to calling the corresponding pressure and temperature results as boundaries for each degree of crankshaft rotation, thereby achieving continuous fluid simulation. By adding dynamic boundary conditions to the simulation algorithm, not only the simulation accuracy is improved, but also the inaccuracy caused by interpolation is solved.

[0057] In some optional implementations, the above step S104 includes:

[0058] Step c1, setting a connecting rod length sequence, the connecting rod length sequence includes a plurality of connecting rod length values, each connecting rod length value in the connecting rod length sequence is used to represent the displacement of the connecting rod as the crankshaft angle changes, and the connecting rod length sequence is used as motion data for controlling the piston position;

[0059] Step c2, obtaining a valve lift curve that changes with the crankshaft angle, and processing the valve lift curve into a valve lift table as motion data for controlling the valve position.

[0060] Specifically, this embodiment controls the movement of the dynamic mesh by setting the connecting rod length, thereby controlling the movement position of the piston. Because the length of the engine connecting rod affects the movement of the piston, the length value of the connecting rod is directly input through the global parameter variable in the simulation software. Since the piston part is processed by the cutting body dynamic mesh, the global variable value can be applied to the piston mesh movement to control the movement of the piston. For the connecting rod length value, a connecting rod length sequence needs to be initialized. The connecting rod length sequence includes multiple connecting rod length values. In the connecting rod length sequence, the arrangement order of each connecting rod length value represents the order in which it is called as a global variable value as the crankshaft angle changes, thereby controlling the movement of the piston.

[0061] In addition, in this embodiment, Figure 4 As shown, it is also necessary to obtain the valve lift curve that changes with the crankshaft angle. The valve lift curve includes the lift changes in the two processes of intake and compression strokes, and includes the lift of the intake valve and exhaust valve respectively. In this way, the valves of the intake and exhaust ducts are controlled separately in the two stages of intake and compression strokes, and the gas enters from the intake duct and is discharged from the exhaust duct, which is closer to the real principle of cylinder operation.

[0062] Similarly, this embodiment also processes the valve lift curve into a valve lift table, creates a separate file for the valve lift data corresponding to each angle, and subsequently calls it according to different file names to achieve continuous motion simulation of the valve, improve simulation accuracy, and solve interpolation problems.

[0063] In some optional implementations, the above step c2 further includes:

[0064] Step c21, obtaining valve clearance parameters;

[0065] Step c22, subtracting the valve clearance parameter from the data in the valve lift table to obtain a processed valve lift table.

[0066] Specifically, when the engine is working, the valve expands due to the increase in temperature. If there is no gap or too small gap between the valve and its transmission parts in the cold state, the thermal expansion in the hot state will cause the valve to close loosely and cause air leakage. In order to eliminate this phenomenon, the three-dimensional cylinder model provided by the present invention reserves a certain gap in the valve and its transmission mechanism, so that the influence of the valve gap needs to be considered when setting the valve lift curve. The embodiment of the present invention specifically represents the valve clearance parameter by setting a global parameter in the three-dimensional software, and deducts the valve clearance parameter from each data in the valve lift table, so that the gap is retained when controlling the valve lift, which can further improve the accuracy of the simulation and improve the accuracy of the simulation software in calculating the swirl ratio and flow rate.

[0067] In some optional implementations, the above step S105 includes:

[0068] Step d1, defining the solution step and solution time, the solution step represents the time per one degree of crankshaft angle rotation, and the solution time represents the duration of the simulation;

[0069] Step d2, defining a first calling function and a second calling function, the first calling function is used to extract boundary data from a boundary table according to a solution step length, and the second calling function is used to extract valve lift data from a valve lift table according to a solution step length;

[0070] Step d3, defining an initial crankshaft angle of the cylinder fluid simulation model;

[0071] Step d4, executing the first calling function and the second calling function according to the solution step length and the initial crankshaft angle, and sequentially extracting the boundary data and valve lift data of each solution step length;

[0072] Step d5, extracting the connecting rod length value corresponding to each solution step from the connecting rod length sequence;

[0073] Step d6, the boundary data, valve lift data and connecting rod length value corresponding to each solution step are sequentially imported into the cylinder fluid simulation model as input data, and the software algorithm is executed within the solution time to obtain the swirl ratio and flow coefficient.

[0074] Specifically, the embodiment of the present invention performs cylinder fluid simulation according to the configuration of the above embodiment. First, the solution step length and solution time need to be defined, wherein the solution step length represents the time per one degree of crankshaft angle rotation, and the solution time represents the duration of the simulation.

[0075] Afterwards, a first calling function and a second calling function are defined, wherein the first calling function is used to extract boundary data from the boundary table according to the solution step length, and the second calling function is used to extract valve lift data from the valve lift table according to the solution step length. In other words, through the first calling function, boundary data corresponding to the crankshaft angle needs to be extracted from the boundary table once after each solution step length; through the second calling function, valve lift data corresponding to the crankshaft angle needs to be extracted from the valve lift table once after each solution step length.

[0076] Since the boundary table and the valve lift table include data corresponding to multiple different crankshaft angles, the purpose of defining the initial crankshaft angle is to clarify the specific position of extracting data from the boundary table and the valve lift table at the initial moment.

[0077] After the above preparations are completed, the first calling function and the second calling function are executed, and the boundary data and valve lift data corresponding to each solution step are extracted in sequence starting from the initial crankshaft angle, and the connecting rod length value corresponding to each solution step is extracted from the connecting rod length sequence, and then the extracted data is imported into the cylinder fluid simulation model as the input of the simulation software, and the simulation calculation is performed by the software, so that the software algorithm is executed within the solution time to obtain the swirl ratio and the flow coefficient. In the embodiment of the present invention, the calculation process of the cylinder fluid simulation model can be automatically realized by software, including but not limited to Fluent, Cradle, Autodesk, etc. The calculation logic of the simulation calculation does not involve special improvements, so it will not be repeated in this embodiment.

[0078] Based on the simulation calculation provided by the embodiment of the present invention, boundary conditions can be added and valve lift changes can be controlled by writing function code relationships, achieving the effect of transient simulation. Compared with the method of fixing temperature and pressure parameters in steady-state simulation, this method makes the simulation process more realistic. In addition, transient calculation does not require interpolation, and the influence of valve movement on the vortex in the cylinder under the entire crankshaft angle is considered, thereby improving the accuracy of simulation calculation.

[0079] In some optional implementations, the above step S106 includes:

[0080] Step e1, determining whether the swirl ratio is greater than or equal to a preset swirl ratio threshold, and determining whether the flow coefficient is greater than or equal to a preset flow threshold;

[0081] Step e2, if the swirl ratio is less than a preset swirl ratio threshold, or the flow coefficient is less than a preset flow threshold, adjusting the shape of the intake duct in the three-dimensional model of the cylinder;

[0082] Step e3: if the swirl ratio is greater than or equal to the preset swirl ratio threshold, and the flow coefficient is greater than or equal to the preset flow threshold, then output the current cylinder three-dimensional model.

[0083] Specifically, when performing airway optimization analysis, preset swirl ratio thresholds and preset flow thresholds required by users are preset, and the calculated swirl ratio and flow coefficient are compared with the corresponding thresholds respectively. If the calculated swirl ratio and flow coefficient are both greater than or equal to the corresponding thresholds, it means that the airway setting of the cylinder is good, which can make the engine's intake and exhaust volume large, the speed fast, and the combustion efficiency high; if at least one of the calculated swirl ratio or flow coefficient is less than the corresponding threshold, it means that the airway shape in the cylinder three-dimensional model needs to be improved, especially the intake duct, which has an impact on the speed and flow of the airflow, and the user needs to readjust the cylinder three-dimensional model and re-simulate. After the user has tried multiple simulations and debugging, the target part that can increase both the swirl ratio and the flow coefficient can be determined on the model according to the change law of the calculation results, and then the user focuses on adjusting the shape of the target part, and finally obtains a cylinder three-dimensional model with a swirl ratio and a flow coefficient greater than or equal to the corresponding threshold, which significantly improves the model adjustment efficiency.

[0084] The technical solution provided by the present invention has the following advantages:

[0085] 1. In the simulation calculation, the influence of the pressure and temperature of the cylinder liner, intake duct and exhaust duct on the vortex in the cylinder as the crankshaft angle changes can be considered, making the calculation results closer to reality;

[0086] 2. You can add boundary conditions and the change of valve lift with crankshaft angle by writing a calling function;

[0087] 3. The influence of piston motion on the vortex in the cylinder is additionally considered;

[0088] 4. Transient calculations do not require interpolation. The crankshaft angle value is selected evenly, and the influence of valve movement on the vortex in the cylinder under the entire crankshaft angle is considered. The calculation results under different crankshaft angles can also be viewed.

[0089] 5. The same calculation model includes the intake duct, exhaust duct and cylinder liner. The airflow enters from the intake and exits from the exhaust. The simulation can take into account the influence of the exhaust duct on the air flow, which is different from the steady-state simulation model that enters from the intake and exits from the cylinder liner without considering the influence of the exhaust duct.

[0090] In this embodiment, an engine airway optimization device is also provided, which is used to implement the above-mentioned embodiments and preferred embodiments, and will not be repeated here. As used below, the term "module" can implement a combination of software and / or hardware of a predetermined function. Although the device described in the following embodiments is preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceivable.

[0091] like Figure 5 As shown, this embodiment provides an engine airway optimization device, comprising:

[0092] A three-dimensional model acquisition module 501 is used to acquire a three-dimensional model of a cylinder of an engine;

[0093] A simulation model generation module 502 is used to divide the three-dimensional model of the cylinder into grids and use dynamic grids for the piston position and valve position to obtain a cylinder fluid simulation model;

[0094] The boundary condition setting module 503 is used to obtain the dynamic boundary conditions of the gas in the cylinder;

[0095] A motion law acquisition module 504, for determining motion data for controlling the piston position and the valve position;

[0096] The simulation calculation module 505 is used to perform simulation calculation on the cylinder fluid simulation model according to the dynamic boundary conditions and motion data of the gas in the cylinder to obtain the swirl ratio and the flow coefficient;

[0097] The airway analysis module 506 is used to adjust the shape of the three-dimensional model of the cylinder according to the swirl ratio and the flow coefficient, and return to the step of dividing the three-dimensional model of the cylinder into grids.

[0098] In some optional implementations, the simulation model generation module 502 includes:

[0099] A meshing unit is used to mesh the cylinder three-dimensional model using a cutting volume mesh and to refine the mesh at small surfaces or gaps;

[0100] A dynamic grid setting unit, used to set the grids of the piston position and the valve position as dynamic grids;

[0101] An airway stretching unit, used to stretch and extend the air inlet and exhaust ducts;

[0102] The physical continuum setting unit is used to specify the fluid region and solid region of the cylinder to obtain a cylinder fluid simulation model.

[0103] In some optional implementations, the boundary condition setting module 503 includes:

[0104] A boundary data acquisition unit is used to collect boundary data through steady flow test. The boundary data is the data of the temperature and pressure of the gas in the cylinder changing with the crankshaft angle;

[0105] The first table processing unit is used to process the boundary data into a boundary table as a dynamic boundary condition.

[0106] In some optional implementations, the motion pattern acquisition module 504 includes:

[0107] A connecting rod length unit is used to set a connecting rod length sequence. The connecting rod length sequence includes a plurality of connecting rod length values. Each connecting rod length value in the connecting rod length sequence is used to represent the displacement of the connecting rod as the crankshaft angle changes. The connecting rod length sequence is used as motion data for controlling the piston position.

[0108] The valve lift unit is used to obtain the valve lift curve that changes with the crankshaft angle, and process the valve lift curve into a valve lift table as motion data for controlling the valve position.

[0109] In some optional embodiments, the valve lift unit comprises:

[0110] A valve clearance acquisition unit, used for acquiring valve clearance parameters;

[0111] The clearance processing unit is used to deduct the valve clearance parameter from the data in the valve lift table to obtain a processed valve lift table.

[0112] In some optional implementations, the simulation calculation module 505 includes:

[0113] A solution parameter definition unit is used to define a solution step and a solution time. The solution step represents the time for each rotation of the crankshaft angle, and the solution time represents the duration of the simulation.

[0114] A calling function definition unit, used to define a first calling function and a second calling function, wherein the first calling function is used to extract boundary data from a boundary table according to a solution step length, and the second calling function is used to extract valve lift data from a valve lift table according to a solution step length;

[0115] An initial rotation angle definition unit is used to define an initial crankshaft rotation angle of a cylinder fluid simulation model;

[0116] A data calling unit, used for executing a first calling function and a second calling function according to a solution step and an initial crankshaft angle, and sequentially extracting boundary data and valve lift data of each solution step;

[0117] A length calling unit is used to extract the connecting rod length value corresponding to each solution step from the connecting rod length sequence;

[0118] The simulation calculation unit is used to import the boundary data, valve lift data and connecting rod length value corresponding to each solution step as input data into the cylinder fluid simulation model in sequence, and execute the software algorithm within the solution time to obtain the swirl ratio and flow coefficient.

[0119] In some optional embodiments, the airway analysis module 506 includes:

[0120] A judgment unit, used to determine whether the swirl ratio is greater than or equal to a preset swirl ratio threshold, and determine whether the flow coefficient is greater than or equal to a preset flow threshold;

[0121] an adjusting unit, for adjusting the shape of the intake port in the three-dimensional model of the cylinder if the swirl ratio is less than a preset swirl ratio threshold, or the flow coefficient is less than a preset flow threshold;

[0122] The output unit is used to output the current three-dimensional model of the cylinder if the swirl ratio is greater than or equal to a preset swirl ratio threshold and the flow coefficient is greater than or equal to a preset flow threshold.

[0123] The further functional description of each of the above modules and units is the same as that of the above corresponding embodiments and will not be repeated here.

[0124] The engine air duct optimization device in this embodiment is presented in the form of a functional unit, where the unit refers to an ASIC (Application Specific Integrated Circuit) circuit, a processor and memory that executes one or more software or fixed programs, and / or other devices that can provide the above-mentioned functions.

[0125] An embodiment of the present invention further provides a computer device having the above-mentioned engine airway optimization device.

[0126] See also Figure 6 , Figure 6 is a schematic diagram of the structure of a computer device provided by an optional embodiment of the present invention, such as Figure 6 As shown, the computer device includes: one or more processors 10, a memory 20, and interfaces for connecting various components, including high-speed interfaces and low-speed interfaces. Various components are connected to each other using different buses for communication, and can be installed on a common mainboard or installed in other ways as needed. The processor can process the instructions executed in the computer device, including instructions stored in or on the memory to display the graphical information of the GUI on an external input / output device (such as, a display device coupled to the interface). In some optional embodiments, if necessary, multiple processors and / or multiple buses can be used together with multiple memories and multiple memories. Similarly, multiple computer devices can be connected, and each device provides some necessary operations (for example, as a server array, a group of blade servers, or a multi-processor system). Figure 6 A processor 10 is taken as an example.

[0127] The processor 10 may be a central processing unit, a network processor or a combination thereof. The processor 10 may further include a hardware chip. The hardware chip may be a dedicated integrated circuit, a programmable logic device or a combination thereof. The programmable logic device may be a complex programmable logic device, a field programmable gate array, a general purpose array logic or any combination thereof.

[0128] The memory 20 stores instructions executable by at least one processor 10, so that at least one processor 10 executes the method shown in the above embodiment.

[0129] The memory 20 may include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function; the data storage area may store data created according to the use of the computer device, etc. In addition, the memory 20 may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some optional embodiments, the memory 20 may optionally include a memory remotely arranged relative to the processor 10, and these remote memories may be connected to the computer device via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0130] The memory 20 may include a volatile memory, such as a random access memory; the memory may also include a non-volatile memory, such as a flash memory, a hard disk or a solid state drive; the memory 20 may also include a combination of the above types of memory.

[0131] The computer device further comprises a communication interface 30 for the computer device to communicate with other devices or a communication network.

[0132] The embodiment of the present invention also provides a computer-readable storage medium. The method according to the embodiment of the present invention can be implemented in hardware, firmware, or can be implemented as a computer code that can be recorded in a storage medium, or can be implemented as a computer code that is originally stored in a remote storage medium or a non-temporary machine-readable storage medium and will be stored in a local storage medium through a network download, so that the method described herein can be stored in such software processing on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only storage memory, a random access memory, a flash memory, a hard disk or a solid-state hard disk, etc.; further, the storage medium can also include a combination of the above types of memories. It can be understood that a computer, a processor, a microprocessor controller, or programmable hardware includes a storage component that can store or receive software or computer code. When the software or computer code is accessed and executed by a computer, a processor, or hardware, the method shown in the above embodiment is implemented.

[0133] A part of the present invention may be applied as a computer program product, such as a computer program instruction, which, when executed by a computer, can call or provide the method and / or technical solution according to the present invention through the operation of the computer. Those skilled in the art should understand that the existence of the computer program instruction in a computer-readable medium includes, but is not limited to, a source file, an executable file, an installation package file, etc., and accordingly, the way in which the computer program instruction is executed by the computer includes, but is not limited to: the computer directly executes the instruction, or the computer compiles the instruction and then executes the corresponding compiled program, or the computer reads and executes the instruction, or the computer reads and installs the instruction and then executes the corresponding installed program. Here, the computer-readable medium may be any available computer-readable storage medium or communication medium accessible to the computer.

[0134] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. An engine airway optimization method, characterized in that: The method comprises: Obtain a three-dimensional model of the cylinder of the engine; Dividing the three-dimensional model of the cylinder into grids, and using dynamic grids for the piston position and the valve position to obtain a cylinder fluid simulation model; Obtain the dynamic boundary conditions of the gas in the cylinder; determining motion data for controlling the piston position and valve position; According to the dynamic boundary conditions of the gas in the cylinder and the motion data, a simulation calculation is performed on the cylinder fluid simulation model to obtain a swirl ratio and a flow coefficient; The shape of the cylinder three-dimensional model is adjusted according to the swirl ratio and the flow coefficient, and the process returns to the step of meshing the cylinder three-dimensional model.

2. The method according to claim 1, characterized in that The three-dimensional model of the cylinder is divided into grids, and a dynamic grid is used for the piston position and the valve position to obtain a cylinder fluid simulation model, including: The three-dimensional model of the cylinder is divided into meshes by using a cutting body, and the meshes are refined at small surfaces or gaps; Set the meshes of piston position and valve position to dynamic meshes; The intake and exhaust ducts are partially stretched and extended; The fluid region and solid region of the cylinder are specified to obtain the cylinder fluid simulation model.

3. The method according to claim 1 or 2, characterized in that: The step of obtaining the dynamic boundary conditions of the gas in the cylinder includes: Collect boundary data through steady flow test, wherein the boundary data is the data of the temperature and pressure of the gas in the cylinder changing with the crankshaft angle; The boundary data is processed into a boundary table as the dynamic boundary condition.

4. The method according to claim 3, characterized in that The determining of motion data for controlling the piston position and the valve position comprises: Setting a connecting rod length sequence, wherein the connecting rod length sequence includes a plurality of connecting rod length values, each connecting rod length value in the connecting rod length sequence is used to represent the displacement of the connecting rod as the crankshaft angle changes, and the connecting rod length sequence is used as motion data for controlling the piston position; A valve lift curve that changes with the crankshaft angle is acquired, and the valve lift curve is processed into a valve lift table as motion data for controlling the valve position.

5. The method according to claim 4, characterized in that The step of processing the valve lift curve into a valve lift table comprises: Get valve clearance parameters; The valve clearance parameter is deducted from the data in the valve lift table to obtain a processed valve lift table.

6. The method according to claim 5, characterized in that The step of performing simulation calculation on the cylinder fluid simulation model according to the dynamic boundary conditions of the gas in the cylinder and the motion data includes: Define a solution step and a solution time, wherein the solution step represents the time for each degree of crankshaft angle rotation, and the solution time represents the duration of the simulation; defining a first calling function and a second calling function, wherein the first calling function is used to extract boundary data from the boundary table according to the solution step length, and the second calling function is used to extract valve lift data from the valve lift table according to the solution step length; defining an initial crankshaft angle of the cylinder fluid simulation model; Execute the first calling function and the second calling function according to the solution step and the initial crankshaft angle, and extract the boundary data and the valve lift data of each solution step in sequence; Extracting the connecting rod length value corresponding to each solution step from the connecting rod length sequence; The boundary data, the valve lift data and the connecting rod length value corresponding to each solution step are sequentially imported into the cylinder fluid simulation model as input data, and the software algorithm is executed within the solution time to obtain the swirl ratio and the flow coefficient.

7. The method according to claim 1, characterized in that The adjusting the shape of the cylinder three-dimensional model according to the swirl ratio and the flow coefficient comprises: Determining whether the swirl ratio is greater than or equal to a preset swirl ratio threshold, and determining whether the flow coefficient is greater than or equal to a preset flow threshold; If the swirl ratio is less than a preset swirl ratio threshold, or the flow coefficient is less than a preset flow threshold, adjusting the shape of the intake port in the three-dimensional model of the cylinder; If the swirl ratio is greater than or equal to a preset swirl ratio threshold, and the flow coefficient is greater than or equal to a preset flow threshold, the current three-dimensional cylinder model is output.

8. An engine airway optimization device, characterized in that: The device comprises: A three-dimensional model acquisition module, used to acquire a three-dimensional model of a cylinder of an engine; A simulation model generation module, used to divide the three-dimensional model of the cylinder into grids, and use dynamic grids for the piston position and the valve position to obtain a cylinder fluid simulation model; Boundary condition setting module, used to obtain the dynamic boundary conditions of the gas in the cylinder; A motion law acquisition module, used to determine motion data for controlling the piston position and the valve position; A simulation calculation module, used for performing simulation calculation on the cylinder fluid simulation model according to the dynamic boundary conditions of the gas in the cylinder and the motion data, so as to obtain a swirl ratio and a flow coefficient; The airway analysis module is used to adjust the shape of the cylinder three-dimensional model according to the swirl ratio and the flow coefficient, and return to the step of dividing the cylinder three-dimensional model into grids.

9. A computer device, characterized in that: include: A memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the method according to any one of claims 1 to 7 by executing the computer instructions.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a computer to execute the method according to any one of claims 1 to 7.

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