CN115341984A - Multi-cylinder engine exhaust manifold, parameter calculation method thereof and related equipment - Google Patents
Multi-cylinder engine exhaust manifold, parameter calculation method thereof and related equipment Download PDFInfo
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- CN115341984A CN115341984A CN202211259964.9A CN202211259964A CN115341984A CN 115341984 A CN115341984 A CN 115341984A CN 202211259964 A CN202211259964 A CN 202211259964A CN 115341984 A CN115341984 A CN 115341984A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
- F01N13/08—Other arrangements or adaptations of exhaust conduits
- F01N13/10—Other arrangements or adaptations of exhaust conduits of exhaust manifolds
- F01N13/107—More than one exhaust manifold or exhaust collector
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- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
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Abstract
The invention provides a multi-cylinder engine exhaust manifold, a parameter calculation method and related equipment thereof, wherein the exhaust manifold comprises a first exhaust manifold group and a second exhaust manifold group; the first exhaust manifold group comprises a first exhaust manifold and a second exhaust manifold, the second exhaust manifold group comprises a third exhaust manifold and a fourth exhaust manifold; the first exhaust manifold group and the second exhaust manifold group have different corresponding outer side exhaust distances, and the design mode ensures that the exhaust back pressures of the cylinders of the two groups of exhaust manifold groups are consistent, thereby improving the smoothness of the exhaust process, weakening the interference of the exhaust gas mixing process in the exhaust manifold to the exhaust process, reducing the pumping loss and the exhaust gas mixing pulse energy loss of the engine, and reducing the exhaust back pressure of the engine.
Description
Technical Field
The invention relates to the field of engine exhaust, in particular to an exhaust manifold of a multi-cylinder engine, a parameter calculation method of the exhaust manifold and related equipment.
Background
The existing engine exhaust pipe is of an equidistant structure, and the center line of an inlet flange of the exhaust pipe is overlapped with the center line of a corresponding cylinder, so that the existing exhaust main pipe is longer in whole, the thermal deformation is large, the thermal stress is high, and the problem of thermal cracking of the exhaust pipe is easy to occur.
In order to solve the problem, a multi-cylinder common-flange exhaust system is provided, and the exhaust system adopts a non-equidistant exhaust pipe structure, wherein every two adjacent cylinders are in a group and share one exhaust flange. Therefore, the exhaust manifolds of the adjacent two cylinders need to be designed simultaneously.
In-cylinder combustion exhaust gas of a turbocharged engine is discharged out of the cylinder through an exhaust valve and enters an exhaust manifold through an exhaust manifold. Each cylinder of the existing engine is provided with an independent flange structure, an exhaust manifold is almost not bent and has long distance, and waste gas in the exhaust manifold is mixed at a position far away from an exhaust valve. In a multi-cylinder common-flange exhaust system, because two adjacent cylinders share the same flange structure, exhaust manifolds of each cylinder in the exhaust system must meet at a position close to the position of an exhaust valve. In the structure, the bending degree of the exhaust manifold is large, the exhaust gas flows out through the exhaust manifold and the exhaust pipe and has two processes of forward flow and reverse flow, and the length of the exhaust manifold is short. Therefore, the air flow disturbance generated in the exhaust manifold in the multi-cylinder common flange exhaust system by the exhaust gas mixing process has influence on the exhaust process, and the exhaust back pressure is increased.
Disclosure of Invention
In view of the above, the present invention provides an exhaust manifold of a multi-cylinder engine, a parameter calculation method thereof and related equipment, so as to improve the smoothness of an exhaust process, and reduce the interference of an exhaust gas mixing process in the exhaust manifold on the exhaust process, thereby reducing the exhaust back pressure of the engine.
In order to solve the technical problems, the invention adopts the following technical scheme:
a multi-cylinder engine exhaust manifold comprising:
a first exhaust manifold group and a second exhaust manifold group;
the first exhaust manifold group comprises a first exhaust manifold and a second exhaust manifold, the second exhaust manifold group comprises a third exhaust manifold and a fourth exhaust manifold;
the first exhaust manifold and the second exhaust manifold are used for providing exhaust passages for the first cylinder;
the third exhaust manifold and the fourth exhaust manifold are used for providing exhaust passages for a second cylinder, and the first cylinder and the second cylinder share one flange;
the first exhaust manifold group and the second exhaust manifold group have different corresponding outer side exhaust distances;
the corresponding outer exhaust distance of the first exhaust manifold group is as follows: the distance between the exhaust valve corresponding to the first exhaust manifold and the intersection of the first exhaust manifold and the second exhaust manifold is larger than that between the exhaust valve corresponding to the second exhaust manifold and the second cylinder;
the corresponding outer side exhaust distance of the second exhaust manifold group is as follows: and the distance between the exhaust valve corresponding to the fourth exhaust manifold and the intersection of the third exhaust manifold and the fourth exhaust manifold is larger than that between the exhaust valve corresponding to the third exhaust manifold and the first cylinder.
Optionally, the exhaust manifold of the multi-cylinder engine includes:
a radius of curvature of the fourth exhaust manifold is smaller than a radius of curvature of the third exhaust manifold, and the first, second, third, and fourth exhaust manifolds are curved facing a center of the flange.
Optionally, the exhaust manifold of the multi-cylinder engine includes:
and recording an exhaust manifold group with exhaust gas countercurrent in the first exhaust manifold group and the second exhaust manifold group as a target exhaust manifold group, wherein the outer exhaust distance corresponding to the target exhaust manifold group is greater than the outer exhaust distance corresponding to the other exhaust manifold group in the first exhaust manifold group and the second exhaust manifold group.
Optionally, the exhaust manifold of the multi-cylinder engine includes:
the sum of the cross sectional areas of the first exhaust manifold and the second exhaust manifold is equal to the cross sectional area of the first total exhaust manifold;
the first total exhaust manifold refers to an exhaust manifold formed after the first exhaust manifold and the second exhaust manifold are converged;
the sum of the cross sectional areas of the third exhaust manifold and the fourth exhaust manifold is equal to the cross sectional area of the second total exhaust manifold;
the second general exhaust manifold refers to an exhaust manifold formed after the third exhaust manifold and the fourth exhaust manifold meet.
Optionally, in the multi-cylinder engine exhaust manifold, the cross sections of the first total exhaust manifold and the second total exhaust manifold are rectangular structures:
the aspect ratio of the rectangular structure is greater than 0.5 and less than 2.
Optionally, in the above multi-cylinder engine exhaust manifold, characterized in that,
the distance between the gas mixing position in the first general exhaust manifold and the gas mixing position in the second general exhaust manifold is larger than 0;
the gas mixing position in the first general exhaust manifold and the second general exhaust manifold refers to a meeting position of the two exhaust manifolds corresponding to the first general exhaust manifold and the second general exhaust manifold.
Optionally, in the exhaust manifold of the multi-cylinder engine, the rectangle is specifically a rounded rectangle.
An engine in which two adjacent cylinders share a flange, the engine further comprising a multi-cylinder engine exhaust manifold as described in any one of the preceding claims.
A vehicle is applied with the engine.
A multi-cylinder engine exhaust manifold parameter calculating method is used for calculating parameters of an exhaust manifold of a multi-cylinder engine combined by the above embodiments, and the method comprises the following steps:
obtaining a design parameter set, wherein each design parameter in the design parameter set comprises X sample points, X is a positive integer greater than 1, and the design parameters comprise: the bending angle of the first exhaust manifold, the bending angle of the fourth exhaust manifold, the outside exhaust distance of the first exhaust manifold group, the outside exhaust distance of the second exhaust manifold group, the cross section length of the first total exhaust manifold, the cross section length of the second total exhaust manifold, the cross section width of the first total exhaust manifold, the cross section width of the second total exhaust manifold, and the longitudinal distance between the gas mixing position and the cylinder;
acquiring an engine one-dimensional simulation model constructed on the basis of the multi-cylinder engine exhaust manifold;
calibrating a one-dimensional simulation model of the engine based on the design parameter set;
carrying out test design based on the engine one-dimensional simulation model to obtain one-dimensional simulation results under each parameter combination working condition, wherein the one-dimensional simulation results at least comprise: cylinder pressure of the engine, air pressure in an exhaust manifold and a mixed exhaust pipe;
calculating to obtain engine pumping loss and waste gas mixed pulse energy loss under each parameter combination working condition based on the one-dimensional simulation result by adopting a pumping loss calculation formula and a waste gas mixed pulse energy loss calculation formula;
constructing a mathematical proxy model by taking the design parameters as independent variables and the pumping loss of the engine and the energy loss of the waste gas mixed pulse as dependent variables;
performing optimization calculation by using the mathematical proxy model and a sequence linear programming method with the minimization of pumping loss and waste gas mixed pulse energy loss as a target to obtain a first target optimization result, wherein the first target optimization result at least comprises target values of all design parameters; wherein the pumping loss and the energy loss of the exhaust gas mixing pulse are weighted by known quantity;
substituting the target values of the design parameters into the one-dimensional engine simulation model to obtain a one-dimensional target simulation result, wherein the one-dimensional target simulation result comprises the following steps: the pumping loss and the waste gas mixed pulse energy loss of each cylinder of the engine under the target value of each design parameter;
establishing an engine three-dimensional simulation model based on the target values of the design parameters, and performing three-dimensional flow calculation to obtain a three-dimensional target simulation result, wherein the three-dimensional target simulation result comprises the following steps: the pumping loss and the waste gas mixed pulse energy loss of each cylinder of the engine under the target value of the design parameter;
judging whether the difference value of the three-dimensional target simulation result and the one-dimensional target simulation result is within an allowable range;
and if the target values of the design parameters are within the allowable range, outputting the target values of the design parameters as a calculation result of the multi-cylinder engine exhaust manifold.
Compared with the prior art, the invention has the following beneficial effects:
the invention provides a multi-cylinder engine exhaust manifold, a parameter calculation method and related equipment thereof, wherein the exhaust manifold comprises a first exhaust manifold group and a second exhaust manifold group; the first exhaust manifold group comprises a first exhaust manifold and a second exhaust manifold, the second exhaust manifold group comprises a third exhaust manifold and a fourth exhaust manifold; the first exhaust manifold group and the second exhaust manifold group have different corresponding outer side exhaust distances, and the design mode ensures that the exhaust back pressures of the cylinders of the two groups of exhaust manifold groups are consistent, thereby improving the smoothness of the exhaust process, weakening the interference of the exhaust gas mixing process in the exhaust manifold to the exhaust process, reducing the pumping loss and the exhaust gas mixing pulse energy loss of the engine, and reducing the exhaust back pressure of the engine.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
FIG. 1 is a front view of an exhaust manifold for a multi-cylinder engine according to an embodiment of the present invention;
FIG. 2 is a side view of an exhaust manifold of a multi-cylinder engine according to an embodiment of the present invention;
FIG. 3 is a flowchart of a method for calculating parameters of an exhaust manifold of a multi-cylinder engine according to an embodiment of the invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In order to clearly understand the technical solution of the present invention, those skilled in the art will now explain the terms used in the present invention.
Pumping loss: during the whole air intake and exhaust process of the engine, the fresh air and the exhaust gas do net work on the piston.
Exhaust pulse energy: each cylinder of the engine periodically discharges exhaust gas, and the energy carried by the exhaust gas is exhaust pulse energy.
An exhaust manifold: and the exhaust gas collecting device is connected with the engine cylinder, and is used for collecting the exhaust gas discharged by each cylinder and then guiding the exhaust gas into an exhaust manifold. For a four-valve engine, there are two exhaust valves and two exhaust manifolds per cylinder.
Multi-cylinder common flange: the exhaust pipes after the exhaust manifolds of the cylinders are converged need to be fixed by a flange structure, and the multi-cylinder common-flange exhaust system means that the exhaust pipes of two adjacent cylinders share one flange structure.
In-cylinder combustion exhaust gas of a turbocharged engine is discharged out of the cylinder through an exhaust valve and enters an exhaust manifold through an exhaust manifold. Existing engines have a separate flange structure for each cylinder. The engine exhaust pipe is of an equidistant structure, the center line of an inlet flange of the exhaust pipe is overlapped with the center line of a corresponding cylinder, the exhaust manifold is almost free of curvature and long in distance, and waste gas in the exhaust manifold is mixed at a position far away from an exhaust valve, so that the existing exhaust main pipe is long in whole, large in thermal deformation, high in thermal stress and easy to crack.
In order to solve the problem, the exhaust system with the multiple cylinders and the flange is provided, the exhaust system adopts a non-equidistant exhaust pipe structure, every two adjacent cylinders in the exhaust pipe structure form a group, the two adjacent cylinders share one exhaust flange, and the exhaust manifold is large in bending degree and short in length.
Because two adjacent cylinders share the same flange structure, exhaust manifolds of each cylinder in the exhaust system must meet in a position close to the position of the exhaust valve. In the structure, the exhaust manifold has large curvature and short length, and the air flow disturbance generated in the exhaust manifold mixing process in the multi-cylinder common-flange exhaust system influences the exhaust process, so that the exhaust back pressure is increased. In addition, the pumping loss and the fuel consumption are increased.
In order to solve the problem, referring to fig. 1, the present application improves an exhaust system with multiple cylinders and a flange, redesigns a design manner of an exhaust manifold (as shown in fig. 1), and each two adjacent cylinders are a group and share one exhaust flange, so that the exhaust manifolds of the two adjacent cylinders need to be designed simultaneously, and structural parameters of the exhaust manifolds are designed according to exhaust requirements and exhaust flow directions of the two adjacent cylinders, so that smoothness of an exhaust process is improved, interference of an exhaust gas mixing process in the exhaust manifold on the exhaust process is reduced, and pumping loss and exhaust gas mixing pulse energy loss of an engine are reduced.
Specifically, the embodiment of the present application discloses a multi-cylinder engine exhaust manifold, and referring to fig. 1, the multi-cylinder engine exhaust manifold includes:
a first exhaust manifold group 100 and a second exhaust manifold group 200;
the first exhaust manifold group 100 includes a first exhaust manifold 101 and a second exhaust manifold 102, and the second exhaust manifold group 200 includes a third exhaust manifold 201 and a fourth exhaust manifold 202;
the first exhaust manifold 101 and the second exhaust manifold 102 are used for providing exhaust passages for first cylinders, which are referred to as 1 in fig. 1; the radius of curvature of the first exhaust manifold 101 is smaller than that of the second exhaust manifold 102, the radius of curvature of the first exhaust manifold 101 is determined by the degree of curvature alpha of the first exhaust manifold 101, the degree of curvature alpha of the first exhaust manifold 101 is shown in fig. 2, and the degree of curvature alpha of the first exhaust manifold 101 refers to the included angle between the axial direction of the exhaust manifold before the first exhaust manifold 101 is bent and the axial direction of the exhaust manifold after the first exhaust manifold 101 is bent;
the third exhaust manifold 201 and the fourth exhaust manifold 202 are used for providing exhaust passages for a second cylinder, and the first cylinder and the second cylinder share one flange, as shown in fig. 1, and the second cylinder is 2 in fig. 1;
the first exhaust manifold group 100 and the second exhaust manifold group 200 have different outer exhaust distances;
the outer exhaust distance L1 corresponding to the first exhaust manifold group 100 is: the distance between an exhaust valve on a first cylinder corresponding to the first exhaust manifold 101 and the intersection of the first exhaust manifold 101 and the second exhaust manifold 102 is equal to the distance between an exhaust valve on the first cylinder and the second exhaust manifold 102, the first cylinder has two exhaust valves, one of the two exhaust valves corresponds to the first exhaust manifold 101, the other exhaust valve corresponds to the second exhaust manifold 102, the distance between the exhaust valve corresponding to the first exhaust manifold 101 and the second cylinder is greater than the distance between the exhaust valve corresponding to the second exhaust manifold 102 and the second cylinder, that is, the exhaust valve on the first cylinder corresponding to the first exhaust manifold 101 is the exhaust valve on the first cylinder far away from the second cylinder;
the outer exhaust distance L2 corresponding to the second exhaust manifold group 200 is: the distance between the exhaust valve corresponding to the fourth exhaust manifold 202 and the intersection of the third exhaust manifold 201 and the fourth exhaust manifold 202 is greater than the distance between the exhaust valve corresponding to the fourth exhaust manifold 202 and the first cylinder, that is, the exhaust valve on the second cylinder corresponding to the fourth exhaust manifold 202 is the exhaust valve on the second cylinder far away from the first cylinder.
In two adjacent cylinders of the multi-cylinder common-flange exhaust system, the process that the waste gas of one cylinder enters an exhaust main pipe through two exhaust manifolds is always concurrent waste gas, and the process that the waste gas of the other cylinder enters the exhaust main pipe through two exhaust manifolds has countercurrent waste gas.
Referring to fig. 1, in the solution disclosed in the embodiment of the present application, the bending directions of the first exhaust manifold 101, the second exhaust manifold 102, the third exhaust manifold 201, and the fourth exhaust manifold 202 may be designed according to the needs of users, in this solution, the first exhaust manifold 101, the second exhaust manifold 102, and the third exhaust manifold 201 and the fourth exhaust manifold 202 may be bent toward each other, that is, the first exhaust manifold 101, the second exhaust manifold 102, the third exhaust manifold 201, and the fourth exhaust manifold 202 are bent toward the center of the flange, where the flange refers to a flange corresponding to the first cylinder and the second cylinder. In order to make the first exhaust manifold 101 meet the second exhaust manifold 102 and the third exhaust manifold 201 meet the fourth exhaust manifold 202, the radius of curvature of the first exhaust manifold 101 is smaller than the radius of curvature of the second exhaust manifold 102 or the curvature of the second exhaust manifold 102, and the radius of curvature of the fourth exhaust manifold 202 is smaller than the radius of curvature of the third exhaust manifold 201 or the curvature of the fourth exhaust manifold 202 is smaller than the curvature of the third exhaust manifold 201.
In design, in order to reduce the exhaust back pressure difference between the first cylinder and the second cylinder, the exhaust manifold group in which exhaust gas counter-flows in the first exhaust manifold group 100 and the second exhaust manifold group 200 is identified as a target exhaust manifold group, and the outer exhaust distance corresponding to the target exhaust manifold group is greater than the outer exhaust distance corresponding to the other exhaust manifold group in the first exhaust manifold group 100 and the second exhaust manifold group 200.
In the solution disclosed in the embodiment of the present application, the first exhaust manifold 101 and the second exhaust manifold 102 are merged on a first total exhaust manifold, and the third exhaust manifold 201 and the fourth exhaust manifold 202 are merged on a second total exhaust manifold, in order to prevent the performance of the engine from being reduced due to the change of the exhaust passage cross-sectional area, in the present solution, the sum of the cross-sectional areas of the first exhaust manifold 101 and the second exhaust manifold 102 is equal to the cross-sectional area of the first total exhaust manifold; the first total exhaust manifold refers to an exhaust manifold formed after the first exhaust manifold 101 and the second exhaust manifold 102 meet; the sum of the cross-sectional areas of the third exhaust manifold 201 and the fourth exhaust manifold 202 is equal to the cross-sectional area of the second total exhaust manifold; the second main exhaust manifold refers to an exhaust manifold formed after the third exhaust manifold and the fourth exhaust manifold meet. By the design mode, the channel cross section of the exhaust channel of the exhaust gas is always in a stable state in the exhaust process.
In another embodiment of the present application, the cross-sectional structures of the first total exhaust manifold and the second total exhaust manifold may be set according to the needs of a user, as long as the cross-sectional area of the first total exhaust manifold and the second total exhaust manifold is equal to the sum of the cross-sectional areas of the two corresponding exhaust manifolds, for example, in this embodiment, the cross-sectional areas of the first total exhaust manifold and the second total exhaust manifold may be a rectangular structure or a circular structure, and when the cross-sectional area of the first total exhaust manifold and the second total exhaust manifold is a rectangular structure, the aspect ratio of the rectangular structure may be greater than 0.5 and less than 2, and more specifically, the rectangular structure may be a rounded rectangle.
In another embodiment of the present disclosure, in order to prevent two groups of main exhaust manifolds from colliding when the engine vibrates, and further affect the stability of the engine structure, in the technical solution disclosed in the embodiment of the present disclosure, a distance between a gas mixing position in the first main exhaust manifold and a gas mixing position in the second main exhaust manifold is greater than 0, that is, a certain gap is provided between the first main exhaust manifold and the second main exhaust manifold, so as to prevent the two main exhaust manifolds from colliding due to the vibration of the engine. The gas mixing position in the first total exhaust manifold and the second total exhaust manifold refers to a meeting position of two exhaust manifolds corresponding to the first total exhaust manifold and the second total exhaust manifold.
Corresponding to the scheme, the application also discloses an engine, and the engine can be applied to the multi-cylinder engine exhaust manifold.
Corresponding to the scheme, the application also discloses a vehicle, and the engine is applied to the vehicle. The vehicle may be any type of existing vehicle that requires an engine, such as a home car, an engineering car, a ship, etc.
In order to further improve the smoothness of the engine exhaust process and weaken the interference of the exhaust gas mixing process in the exhaust manifold on the exhaust process. The invention also provides a parameter calculation method for optimizing various design parameters in the exhaust manifold of the multi-cylinder engine, and the calculation method is a multivariable optimization process with the aim of minimizing pumping loss and waste gas mixed pulse energy loss. The method for calculating the parameters of the exhaust manifold of the multi-cylinder engine is used for calculating the parameters of the exhaust manifold of the multi-cylinder engine combined in the above embodiments, specifically, referring to fig. 3, the method for calculating the parameters of the exhaust manifold of the multi-cylinder engine disclosed in the embodiment of the present application may include:
step S101: acquiring a design parameter set;
each design parameter in the design parameter set includes X sample points, where X is a positive integer greater than 1, and in this scheme, the value of X may be 1000, and the design parameters include: the bending angle of the first exhaust manifold, the bending angle of the fourth exhaust manifold, the outside exhaust distance of the first exhaust manifold group, the outside exhaust distance of the second exhaust manifold group, the cross section length of the first total exhaust manifold, the cross section length of the second total exhaust manifold, the cross section width of the first total exhaust manifold, the cross section width of the second total exhaust manifold, and the longitudinal distance between the gas mixing position and the cylinder;
after the interval range of each design parameter is determined, 1000 sample points of each design parameter can be determined by utilizing a latin hypercube method or other sampling modes, and the design points are imported into the design parameter set, that is, each design parameter can have 1000 different values, or 1000 total sample points are established together based on the combination of the different values in each design parameter, that is, a combination of 1000 different design parameters is established in total, wherein the value of at least one design parameter in the combinations is different, and the 1000 combinations are imported into the design parameter set.
Step S102: obtaining an engine one-dimensional simulation model constructed based on the multi-cylinder engine exhaust manifold;
in the step, the engine model to which the scheme is applied is selected, and a one-dimensional simulation model matched with the engine model and the multi-cylinder engine exhaust manifold structure is created. The one-dimensional simulation model may generate a corresponding one-dimensional simulation result based on the design parameters in the design parameter set, and the one-dimensional simulation result may include: the cylinder pressure of the engine, the air pressure in the exhaust manifold and the mixed exhaust pipe can also comprise an exhaust flow curve.
Step S103: calibrating an engine one-dimensional simulation model based on the design parameter set, and performing test design based on the engine one-dimensional simulation model to obtain one-dimensional simulation results under each parameter combination working condition;
in the scheme, after the design parameter set and the one-dimensional engine simulation model are determined, the one-dimensional engine simulation model is calibrated by adopting the combination of various design parameters in the design parameter set, and the calibrated one-dimensional engine simulation model is adopted to obtain the one-dimensional simulation result under the corresponding calibration condition, so that the one-dimensional simulation result output by the one-dimensional engine simulation model under the condition of the combination of various different design parameters can be obtained.
Step S104: calculating to obtain the pumping loss of the engine and the energy loss of the mixed pulse of the waste gas under the working condition of each parameter combination by adopting a pumping loss calculation formula and a waste gas mixed pulse energy loss calculation formula based on the one-dimensional simulation result;
after one-dimensional simulation results under each parameter combination working condition are obtained, extracting the cylinder pressure of the engine, the air pressure in an exhaust manifold and the air pressure in a mixed exhaust pipe in the one-dimensional simulation results, substituting the cylinder pressure of the engine, the air pressure in the exhaust manifold and the air pressure in the mixed exhaust pipe into a pumping loss calculation formula and an exhaust gas mixed pulse energy loss calculation formula, and calculating to obtain pumping loss and exhaust gas mixed pulse energy loss of the engine under each parameter combination working condition;
assuming that the gas states in the two exhaust manifolds of the same cylinder are consistent, the pumping loss and the energy loss of the exhaust gas mixing pulse are calculated according to the following formula.
The pumping loss calculation formula is as follows:
calculating the energy loss of the exhaust gas mixing pulse:
in the formula, subscript 1 and subscript 2 represent a first cylinder and a second cylinder, respectively. exo is the exhaust valve opening phase, exc is the exhaust valve closing phase, p exh Is the exhaust gas pressure in the exhaust manifold (i.e., the pressure in the exhaust manifold), p cl Is the cylinder pressure of the engine, p d Is the difference in exhaust gas pressure before and after mixing (i.e., the gas pressure in the exhaust pipe after mixing).nIs the rotating speed of the motor, and the rotating speed is the rotating speed,ithe number of the cylinders is the number of the cylinders,Vthe single-cylinder displacement is adopted,θis the angle of rotation of the crankshaft,His the enthalpy.
Step S105: constructing a mathematical proxy model by taking the design parameters as independent variables and taking the pumping loss of the engine and the energy loss of the waste gas mixed pulse as dependent variables;
in this step, in order to optimize design parameters, a mathematical proxy model may be created based on a neural network algorithm or a response surface method, and when the mathematical proxy model is created, the dependent variables of the mathematical proxy model are the engine pumping loss and the exhaust gas mixed pulse energy loss, and the independent variables of the mathematical proxy model are the above design parameters. That is, the input of the mathematical proxy model is a design parameter, and the output of the mathematical proxy model is an engine pumping loss and an exhaust gas mixing pulse energy loss corresponding to the design parameter.
In the process, a learning sample and a verification sample are established based on the design parameter set and the corresponding engine pumping loss and the exhaust gas mixed pulse energy loss under each parameter combination working condition obtained by the engine one-dimensional simulation model, and the mathematical agent model is learned and trained based on the learning sample and the verification sample to obtain the mathematical agent model with required precision.
Step S106: performing optimization calculation by using the mathematical proxy model and a sequence linear programming method with the minimization of pumping loss and waste gas mixed pulse energy loss as a target to obtain a first target optimization result, wherein the first target optimization result at least comprises target values of all design parameters; wherein the pumping loss and the energy loss of the exhaust gas mixing pulse are weighted by known quantity;
after the mathematical agent model is trained, the mathematical agent model performs optimization calculation by using a sequential linear programming method with the minimum pumping loss and the minimum exhaust gas mixed pulse energy loss as a target and the value range of the design parameters as preset conditions, so as to obtain target values of the design parameters corresponding to the minimum pumping loss and the minimum exhaust gas mixed pulse energy loss, and generate a first target optimization result, wherein the first target optimization result at least comprises the target values of the design parameters, the weight of the pumping loss and the weight of the exhaust gas mixed pulse energy loss are known quantities, the weight of the pumping loss and the weight of the exhaust gas mixed pulse energy loss can be determined according to user requirements, and when the weight of the pumping loss and the weight of the exhaust gas mixed pulse energy loss are changed, the obtained target values of the design parameters may be changed. Specifically, the minimum pumping loss and the minimum exhaust gas mixing pulse energy loss means that the product of the pumping loss and the weight thereof plus the product of the mixing pulse energy loss and the weight thereof is minimum, for example, the value of a + b + c + d is minimum, where a is the pumping loss, b is the weight corresponding to the pumping loss, c is the mixing pulse energy loss, and d is the weight of the mixing pulse energy loss.
Step S107: substituting the target value of each design parameter into the one-dimensional engine simulation model to obtain a one-dimensional target simulation result;
in this step, in order to further verify the reliability of the calculation result of the mathematical agent model, the target value of each design parameter may be substituted into the one-dimensional engine simulation model, and the one-dimensional target simulation result matches with the target value of each design parameter, where the one-dimensional target simulation result includes: and the pump air loss and the waste gas mixed pulse energy loss of each cylinder of the engine under the target value of each design parameter.
Step S108: establishing an engine three-dimensional simulation model based on the target values of the design parameters, and performing three-dimensional flow calculation to obtain a three-dimensional target simulation result;
in this solution, an engine three-dimensional simulation model is established based on the target values of the design parameters, and three-dimensional flow calculation is performed to obtain a three-dimensional target simulation result, where the three-dimensional target simulation result may include: and (3) the pumping loss and the waste gas mixing pulse energy loss of each cylinder of the engine under the target value of the design parameter.
Step S109: judging whether the difference value of the three-dimensional target simulation result and the one-dimensional target simulation result is within an allowable range;
the three-dimensional target simulation result may include engine pumping loss and exhaust gas mixed pulse energy loss which are obtained by a three-dimensional simulation model and are matched with the target values of the design parameters, the three-dimensional target simulation result is compared with a one-dimensional target simulation result, whether a difference between the two is within an allowable range (whether an engine pumping loss difference is within the allowable range and whether an exhaust gas mixed pulse energy loss difference is within the allowable range) is judged, for example, whether a deviation is less than or equal to 3%, if the deviation is less than or equal to 3%, it is indicated that the difference between the three-dimensional target simulation result and the one-dimensional target simulation result is within the allowable range, step S110 is executed, if the deviation is greater than 3%, it is indicated that the difference between the three-dimensional target simulation result and the one-dimensional target simulation result is not within the allowable range, at this time, the reliability verification is performed on the one-dimensional simulation model and the three-dimensional simulation model, and the unreliable correction on the unreliable one-dimensional simulation model, the re-execution step is executed after the one-dimensional simulation model is corrected, if the one-dimensional simulation model is unreliable: calibrating the one-dimensional simulation model of the engine based on the design parameter set, and performing the following steps, if the three-dimensional simulation model is unreliable, performing the steps again: and establishing a three-dimensional simulation model of the engine based on the target values of the design parameters, and performing three-dimensional flow calculation to obtain a three-dimensional target simulation result.
Step S110: and if the target values of the design parameters are within the allowable range, outputting the target values of the design parameters as a calculation result of the multi-cylinder engine exhaust manifold.
And when the difference value between the three-dimensional target simulation result and the one-dimensional target simulation result is within an allowable range, indicating that the target value of the design parameter is a reliable value, and outputting the target value of the design parameter as a calculation result of the multi-cylinder engine exhaust manifold.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A multi-cylinder engine exhaust manifold, comprising:
a first exhaust manifold group and a second exhaust manifold group;
the first exhaust manifold group comprises a first exhaust manifold and a second exhaust manifold, the second exhaust manifold group comprises a third exhaust manifold and a fourth exhaust manifold;
the first exhaust manifold and the second exhaust manifold are used for providing exhaust passages for the first cylinder;
the third exhaust manifold and the fourth exhaust manifold are used for providing exhaust passages for a second cylinder, and the first cylinder and the second cylinder share one flange;
the first exhaust manifold group and the second exhaust manifold group have different corresponding outer exhaust distances;
the corresponding outer exhaust distance of the first exhaust manifold group is as follows: the distance between the exhaust valve corresponding to the first exhaust manifold and the intersection of the first exhaust manifold and the second exhaust manifold is larger than that between the exhaust valve corresponding to the second exhaust manifold and the second cylinder;
the corresponding outer side exhaust distance of the second exhaust manifold group is as follows: and the distance between the exhaust valve corresponding to the fourth exhaust manifold and the intersection of the third exhaust manifold and the fourth exhaust manifold is larger than that between the exhaust valve corresponding to the third exhaust manifold and the first cylinder.
2. The multi-cylinder engine exhaust manifold of claim 1, comprising:
the fourth exhaust manifold has a radius of curvature less than a radius of curvature of the third exhaust manifold, and the first, second, third, and fourth exhaust manifolds are curved toward a center of the flange.
3. A multi-cylinder engine exhaust manifold according to claim 1, comprising:
and recording an exhaust manifold group with exhaust gas countercurrent in the first exhaust manifold group and the second exhaust manifold group as a target exhaust manifold group, wherein the outer exhaust distance corresponding to the target exhaust manifold group is greater than the outer exhaust distance corresponding to the other exhaust manifold group in the first exhaust manifold group and the second exhaust manifold group.
4. The multi-cylinder engine exhaust manifold of claim 1, comprising:
the sum of the cross sectional areas of the first exhaust manifold and the second exhaust manifold is equal to the cross sectional area of the first total exhaust manifold;
the first total exhaust manifold refers to an exhaust manifold formed after the first exhaust manifold and the second exhaust manifold are converged;
the sum of the cross sectional areas of the third exhaust manifold and the fourth exhaust manifold is equal to the cross sectional area of the second total exhaust manifold;
the second general exhaust manifold refers to an exhaust manifold formed after the third exhaust manifold and the fourth exhaust manifold meet.
5. The multi-cylinder engine exhaust manifold of claim 4, wherein the cross-section of the first and second total exhaust manifolds is a rectangular structure:
the aspect ratio of the rectangular structure is greater than 0.5 and less than 2.
6. The multi-cylinder engine exhaust manifold of claim 4,
the distance between the gas mixing position in the first general exhaust manifold and the gas mixing position in the second general exhaust manifold is larger than 0;
the gas mixing position in the first main exhaust manifold and the second main exhaust manifold refers to the intersection position of the two exhaust manifolds corresponding to the first main exhaust manifold and the second main exhaust manifold.
7. A multi-cylinder engine exhaust manifold according to claim 5, wherein the rectangle is in particular a rounded rectangle.
8. An engine wherein two adjacent cylinders in the engine share a flange, the engine further comprising a multi-cylinder engine exhaust manifold according to any one of claims 1 to 7.
9. A vehicle, characterized in that the engine of claim 8 is applied.
10. A multi-cylinder engine exhaust manifold parameter calculation method for calculating a parameter of a multi-cylinder engine exhaust manifold combined according to claims 1 to 7, the method comprising:
obtaining a design parameter set, wherein each design parameter in the design parameter set includes X sample points, X is a positive integer greater than 1, and the design parameters include: the bending angle of the first exhaust manifold, the bending angle of the fourth exhaust manifold, the outside exhaust distance of the first exhaust manifold group, the outside exhaust distance of the second exhaust manifold group, the cross section length of the first total exhaust manifold, the cross section length of the second total exhaust manifold, the cross section width of the first total exhaust manifold, the cross section width of the second total exhaust manifold, and the longitudinal distance between the gas mixing position and the cylinder;
acquiring an engine one-dimensional simulation model constructed on the basis of the multi-cylinder engine exhaust manifold;
calibrating a one-dimensional simulation model of the engine based on the design parameter set;
carrying out test design based on the engine one-dimensional simulation model to obtain one-dimensional simulation results under each parameter combination working condition, wherein the one-dimensional simulation results at least comprise: cylinder pressure of the engine, air pressure in an exhaust manifold and a mixed exhaust pipe;
calculating to obtain the pumping loss of the engine and the energy loss of the mixed pulse of the waste gas under the working condition of each parameter combination by adopting a pumping loss calculation formula and a waste gas mixed pulse energy loss calculation formula based on the one-dimensional simulation result;
constructing a mathematical proxy model by taking the design parameters as independent variables and the pumping loss of the engine and the energy loss of the waste gas mixed pulse as dependent variables;
performing optimization calculation by using the mathematical proxy model and a sequence linear programming method with the minimization of pumping loss and waste gas mixed pulse energy loss as a target to obtain a first target optimization result, wherein the first target optimization result at least comprises target values of all design parameters; wherein the pumping loss and the energy loss of the exhaust gas mixing pulse are weighted by known quantity;
substituting the target values of the design parameters into the one-dimensional engine simulation model to obtain a one-dimensional target simulation result, wherein the one-dimensional target simulation result comprises the following steps: the pumping loss and the waste gas mixed pulse energy loss of each cylinder of the engine under the target value of each design parameter;
establishing an engine three-dimensional simulation model based on the target values of the design parameters, and performing three-dimensional flow calculation to obtain a three-dimensional target simulation result, wherein the three-dimensional target simulation result comprises the following steps: the pumping loss and the waste gas mixed pulse energy loss of each cylinder of the engine under the target value of the design parameter;
judging whether the difference value of the three-dimensional target simulation result and the one-dimensional target simulation result is within an allowable range;
and if the target value is within the allowable range, outputting the target value of each design parameter as a calculation result of the multi-cylinder engine exhaust manifold.
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