CN117951829A

CN117951829A - Engine crankshaft system parameter determination method and device

Info

Publication number: CN117951829A
Application number: CN202410021771.2A
Authority: CN
Inventors: 吴田田; 王江涛; 张继明; 张文龙; 庹汉郧
Original assignee: Dongfeng Motor Group Co Ltd
Current assignee: Dongfeng Motor Group Co Ltd
Priority date: 2024-01-05
Filing date: 2024-01-05
Publication date: 2024-04-30

Abstract

The application discloses a method and a device for determining engine crankshaft system parameters, wherein the method is applied to a server, loads when different main bearing key design parameters are configured are obtained through a virtual crank connecting rod mechanism model, the strength and friction work of the main bearing are determined according to the loads and the key design parameters, screening conditions are set, and the main bearing key design parameters meeting the requirements are screened according to the screening conditions. In the conceptual design stage of the engine, the application balances the strength reliability requirement and friction power loss of the main bearing, selects reasonable diameter and width of the main bearing, ensures the reliable durability of the main bearing, effectively reduces the friction loss of the main bearing, and effectively improves the thermal efficiency and the economical efficiency of the engine.

Description

Engine crankshaft system parameter determination method and device

Technical Field

The invention relates to the technical field of engines, in particular to a method and a device for determining engine crankshaft system parameters.

Background

Under the big trend of new energy power assembly technology, for traditional engines, the improvement of thermal efficiency is a problem of working emphasis and difficulty at the present stage. The friction reduction technology improves the thermal efficiency of the engine by reducing friction loss, has high cost performance and becomes one of important ways for improving the thermal efficiency and the economy of the automobile engine. According to statistics, the friction loss of the main bearing accounts for about 20-35% of the friction loss of the whole engine, and therefore, the heat efficiency and the economy of the engine can be obviously improved by effectively reducing the friction loss of the main bearing.

The key design parameters of the main bearing are basic parameters of a crank connecting rod mechanism and are also important factors for evaluating the friction loss of the main bearing, in general, the key design parameters of the main bearing are selected and defined in the conceptual design stage of the engine, the design change can not occur basically in the subsequent detailed design stage, and the trial-manufacturing sample of the main bearing is required to be defined according to the key design parameters in the trial-manufacturing stage, so that the key design parameters of the main bearing are critical in selection in the conceptual design stage of the engine, and are key technical directions for effectively reducing the friction loss of the main bearing and effectively improving the thermal efficiency and economy of the engine.

Disclosure of Invention

The application provides a method and a device for determining engine crankshaft system parameters, which are used for solving the technical problem that the heat efficiency of an engine is difficult to improve.

The present application has been made in view of the above-mentioned problems, and it is an object of the present application to provide a method and apparatus for determining engine crankshaft parameters that overcomes or at least partially solves the above-mentioned problems.

The first aspect provides a method for determining engine crankshaft system parameters, which is applied to a server, wherein the server is preconfigured with a virtual crank connecting rod mechanism model, the virtual crank connecting rod mechanism model comprises a virtual piston group model, a virtual connecting rod model, a virtual crankshaft model and a virtual main bearing model, the virtual piston group model, the virtual connecting rod model and the virtual crankshaft model are sequentially in transmission connection, and the virtual main bearing model is sleeved on a main journal of the virtual crankshaft model; the method comprises the following steps:

Configuring key design parameters of different virtual main bearing models at different moments, and recording a set of key design parameters of the configured virtual main bearing models;

Loading excitation to the virtual piston group model at different moments, wherein the virtual piston group model makes reciprocating linear motion, drives the virtual connecting rod model to make plane motion, and the virtual connecting rod model drives the virtual crankshaft model to make rotary motion, so that the load of the virtual main bearing model is detected respectively; wherein the excitation is obtained according to a real cylinder pressure curve when the engine is running;

obtaining the strength of the virtual main bearing model according to the load of the virtual main bearing model and key design parameters of the virtual main bearing model, and determining the friction work of the virtual main bearing model;

Setting screening conditions according to the strength of the virtual main bearing model and the friction work of the virtual main bearing model, and determining the key design parameters of the virtual main bearing model meeting the screening conditions from the set of key design parameters of the virtual main bearing model.

Optionally, setting screening conditions according to the strength of the virtual main bearing model and the friction work of the virtual main bearing model includes:

setting a first screening condition according to the intensity of the virtual main bearing model to obtain a first screening function, wherein the first screening condition is as follows: the strength of the virtual main bearing model is less than or equal to the yield strength of the virtual main bearing model;

Setting a second screening condition according to the friction work of the virtual main bearing model to obtain a second screening function, wherein the second screening condition is as follows: the friction work of the virtual main bearing model is minimum;

determining the key design parameters of the virtual main bearing model meeting the screening conditions from the set of key design parameters of the virtual main bearing model, comprising: and determining the key design parameters of the virtual main bearing model which meet the first screening function and the second screening function from the set of key design parameters of the virtual main bearing model.

Optionally, the key design parameters include a diameter of the virtual main bearing model, a width of the virtual main bearing model.

Optionally, obtaining the strength of the virtual main bearing model according to the load of the virtual main bearing model and the key design parameters of the virtual main bearing model includes:

Determining an effective bearing area of the virtual main bearing model according to the formula a=d _mb·L_mb;

Wherein A is the effective bearing area of the virtual main bearing model, D _mb is the diameter of the virtual main bearing model, and L _mb is the width of the virtual main bearing model;

According to the formula Determining that the intensity of the virtual main bearing model satisfies the following formula

Wherein σ _mb is the strength of the virtual main bearing model, MAX [ F _mb ] is the load maximum of the virtual main bearing model, and F _mb is the load of the virtual main bearing model.

Optionally, setting a first screening condition according to the intensity of the virtual main bearing model to obtain a first screening function, including:

Determining a first screening condition according to the formula sigma _mb≤σ_s; wherein σ _s is the yield strength of the virtual main bearing model;

according to the formula sigma _mb≤σ_s Determining that the first screening function satisfies the formula/>

Alternatively, according to the formulaDetermining the load of the virtual main bearing model;

wherein, F _mb is the load of the virtual main bearing model, F is the excitation of the virtual piston group model, ψ is the crank angle of the virtual crank model, r is the crank radius of the virtual crank model, and L is the connecting rod length of the virtual connecting rod model;

According to the formula Determining an excitation F for model loading of the virtual piston group;

Wherein F is excitation for loading the virtual piston group model, D is a cylinder diameter configured in a virtual crank mechanism model, p _g is in-cylinder gas combustion pressure configured in a cylinder pressure curve, n is an engine speed configured in the virtual crank mechanism model, m _j is a reciprocating mass configured in the virtual crank mechanism model, ψ is a crank angle of the virtual crank mechanism model, and r is a crank radius of the virtual crank mechanism model.

Optionally, setting a second screening condition according to the friction work of the virtual main bearing model to obtain a second screening function, including:

According to the second screening condition, determining that the second screening function satisfies the formula: (D, L) =argmin C _FMEP(D_mb,L_mb);

Wherein, (D, L) is the combination of the diameter value and the width value of the virtual main bearing model when the friction work of the virtual main bearing model is minimum; c _FMEP is the friction work of the virtual main bearing model, D _mb is the diameter of the virtual main bearing model, and L _mb is the width of the virtual main bearing model.

Optionally, detecting the friction work of the virtual main bearing model includes:

According to the formula Determining oil film lubrication friction work of a virtual main bearing model;

According to the formula Determining oil seal friction work of a virtual main bearing model;

According to the formula Determining hydraulic loss friction work of the virtual main bearing model;

determining the friction work of the virtual main bearing model according to a formula C _FMEP＝C_FMEP1+C_FMEP2+C_FMEP3;

Wherein, C _FMEP is the friction work of the virtual main bearing model, C _FMEP1 is the oil film lubrication friction work of the virtual main bearing model, C _FMEP2 is the oil seal friction work of the virtual main bearing model, and C _FMEP3 is the hydraulic loss friction work of the virtual main bearing model; c ₁ is an oil film lubrication friction power correction coefficient configured in the virtual main bearing model, C ₂ is an oil seal friction power correction coefficient configured in the virtual main bearing model, and C ₃ is a hydraulic loss friction power correction coefficient configured in the virtual main bearing model; mu' is an engine oil viscosity correction coefficient configured in the virtual crank-connecting rod mechanism model, n is an engine speed configured in the virtual crank-connecting rod mechanism model, D _mb is a diameter of the virtual main bearing model, L _mb is a width of the virtual main bearing model, n _mb is the number of the virtual main bearing models, D is a cylinder diameter configured in the virtual crank-connecting rod mechanism model, B is a piston stroke of the virtual piston group model, and i is the number of engine cylinders configured in the virtual crank-connecting rod mechanism model; the engine oil viscosity correction coefficient satisfies the formula Mu is the viscosity of the engine oil configured in the virtual crank-connecting rod mechanism model, and mu ₀ is the standard value of the viscosity of the engine oil configured in the virtual crank-connecting rod mechanism model.

Optionally, configuring key design parameters of different virtual main bearing models at different moments, and recording a set of key design parameters of the configured virtual main bearing models, including:

Configuring different diameters of the virtual main bearing models and widths of the virtual main bearing models at different moments, and recording a set of the configured diameters of the virtual main bearing models and the widths of the virtual main bearing models;

Determining key design parameters of the virtual main bearing model satisfying the first screening function and the second screening function from a set of key design parameters of the virtual main bearing model, comprising:

substituting the set of the diameter of the virtual main bearing model and the width of the virtual main bearing model into a first screening function, and screening out the set of the diameter of the virtual main bearing model and the width of the virtual main bearing model which meet the first screening condition;

Substituting the set of the diameter of the virtual main bearing model and the width of the virtual main bearing model which meet the first screening condition into a second screening function, and screening out the diameter of the virtual main bearing model and the width of the virtual main bearing model which meet the second screening condition.

The second aspect provides an engine crankshaft system parameter determining device, which is applied to a server, wherein the server is preconfigured with a virtual crank connecting rod mechanism model, the virtual crank connecting rod mechanism model comprises a virtual piston group model, a virtual connecting rod model, a virtual crankshaft model and a virtual main bearing model, the virtual piston group model, the virtual connecting rod model and the virtual crankshaft model are sequentially in transmission connection, and the virtual main bearing model is sleeved on a main journal of the virtual crankshaft model; the device comprises:

The parameter configuration unit is used for configuring key design parameters of different virtual main bearing models at different moments and recording a set of the key design parameters of the configured virtual main bearing models;

the detection unit is used for loading excitation to the virtual piston group model at different moments, the virtual piston group model performs reciprocating linear motion, the virtual connecting rod model is driven to perform plane motion, the virtual connecting rod model drives the virtual crankshaft model to perform rotary motion, and the loads of the virtual main bearing model are respectively detected; wherein the excitation is obtained according to a real cylinder pressure curve when the engine is running;

the intensity and friction work determining unit is used for obtaining the intensity of the virtual main bearing model and determining the friction work of the virtual main bearing model according to the load of the virtual main bearing model and key design parameters of the virtual main bearing model;

And the screening unit is used for setting screening conditions according to the strength of the virtual main bearing model and the friction work of the virtual main bearing model, and determining the key design parameters of the virtual main bearing model meeting the screening conditions from the set of key design parameters of the virtual main bearing model.

In a third aspect, a server is provided, comprising: a memory, a processor, and a computer program stored on the memory, the computer program configured to implement the steps of the engine crankshaft series parameter determination method of the first aspect when called by the processor.

The technical scheme provided by the embodiment of the application has at least the following technical effects or advantages:

According to the method and the device for determining the crankshaft system parameters of the engine, the load when different main bearing key design parameters are configured is obtained through the virtual crank connecting rod mechanism model, the strength and friction work of the main bearing are determined according to the load and the key design parameters, screening conditions are set, and the main bearing key design parameters meeting the requirements are screened according to the screening conditions, so that the main bearing key design parameters are reasonably selected, the main bearing strength reliability requirements and friction work losses are balanced, the main bearing friction losses are effectively reduced, and the thermal efficiency and the economical efficiency of the engine are effectively improved in the conceptual design stage of the engine.

According to the application, through the application of the virtual crank connecting rod mechanism model, the calculation and judgment of the intensity reliability and friction work of the main bearing can be constructed aiming at different crankshaft systems, the rapid model selection of key design parameters of the main bearing is realized, the optimal key design parameters of the main bearing are obtained, and the design that the intensity reliability of the main bearing meets the standard and the friction loss of the main bearing is optimized is realized.

The foregoing description is only an overview of the present application, and is intended to be implemented in accordance with the teachings of the present application in order that the same may be more clearly understood and to make the same and other objects, features and advantages of the present application more readily apparent.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the application. Also, like reference numerals are used to designate like parts throughout the figures. In the drawings:

FIG. 1 is a schematic diagram of a virtual crank-link mechanism model in an embodiment of the present application;

FIG. 2 is a flowchart of a method for determining engine crankshaft parameters in an embodiment of the present application;

FIG. 3 is a diagram showing the force transmission of a crank-link mechanism according to an embodiment of the present application;

FIG. 4 is a schematic diagram of a cylinder pressure curve in an embodiment of the application;

FIG. 5 is a diagram illustrating a crank-link mechanism force analysis according to an embodiment of the present application;

FIG. 6 is a diagram illustrating a principal axis bearing force analysis according to an embodiment of the present application;

FIG. 7 is a schematic diagram of an engine crankshaft system parameter determination apparatus according to an embodiment of the present application;

FIG. 8 is a flowchart illustrating a specific control scheme for determining engine crankshaft parameters in accordance with an embodiment of the present application.

Detailed Description

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings.

Various structural schematic diagrams according to embodiments of the present application are shown in the accompanying drawings. The figures are not drawn to scale, wherein certain details are exaggerated for clarity of presentation and may have been omitted. The shapes of the various regions, layers and relative sizes, positional relationships between them shown in the drawings are merely exemplary, may in practice deviate due to manufacturing tolerances or technical limitations, and one skilled in the art may additionally design regions/layers having different shapes, sizes, relative positions as actually required.

In order to better understand the above technical solutions, the following detailed description will be made with reference to specific embodiments, and it should be understood that specific features in the embodiments and examples of the disclosure are detailed descriptions of the technical solutions of the present disclosure, and not limiting the technical solutions of the present disclosure, and the technical features in the embodiments and examples of the present disclosure may be combined with each other without conflict.

Under the great trend of new energy power assembly technology, for the traditional engine, the improvement of the thermal efficiency is the key and difficult problem of the current work. The friction reduction technology improves the thermal efficiency of the engine by reducing friction loss, has high cost performance and becomes one of important ways for improving the thermal efficiency and the economy of the automobile engine. According to statistics, the friction loss of the main bearing accounts for about 20-35% of the friction loss of the whole engine, and therefore, the heat efficiency and the economy of the engine can be obviously improved by effectively reducing the friction loss of the main bearing. The prior patent CN111125859A discloses a construction method of a friction model of an engine crankshaft system, and establishes a calculation model containing a friction coefficient of the crankshaft system, wherein the calculation model comprises a main bearing seal friction calculation model, a main bearing hydrodynamic friction calculation model and a flow loss calculation model of engine oil between journals; generating a basic engine crankshaft system friction model consisting of a main bearing seal friction calculation model, a main bearing hydrodynamic friction calculation model and an engine oil flow loss calculation model between journals; and determining a crankshaft system friction coefficient of the calculation model by using a test result of the engine friction decomposition test and a basic engine crankshaft system friction model, and substituting the crankshaft system friction coefficient into the basic engine crankshaft system friction model to obtain the engine. According to the method, corresponding friction models are built for different crankshaft systems, the purpose of rapidly evaluating friction of the engine crankshaft system is achieved, and a friction model based on the crankshaft system is provided for subsequent optimization of related part design. The patent focuses on how to construct a friction model which can only be used for evaluating the friction condition of a crankshaft system of an engine when in use, cannot evaluate the strength of the crankshaft system, cannot construct the reliability of the strength of the main bearing and the calculation and judgment of friction work, cannot realize the quick model selection of key design parameters of the main bearing, and can acquire the optimal key design parameters of the main bearing.

In view of this, the present application provides a method for determining engine crankshaft parameters, which is applied to a server, where the server is preconfigured with a virtual crank-link mechanism model, as shown in fig. 1, fig. 1 is a schematic diagram of the virtual crank-link mechanism model in the embodiment of the present application, the virtual crank-link mechanism model 100 includes a virtual piston set model 101, a virtual link model 102, a virtual crankshaft model 103, and a virtual main bearing model 104, where the virtual piston set model 101, the virtual link model 102, and the virtual crankshaft model 103 are sequentially connected in a transmission manner, and the virtual main bearing model 104 is sleeved on a main journal of the virtual crankshaft model 103. The virtual crank connecting rod mechanism model 100 is adopted to obtain the load of the virtual main bearing model 104 when different main bearing key design parameters are configured, the strength and friction work of the main bearing are determined according to the load and the key design parameters, screening conditions are set, and the main bearing key design parameters meeting the requirements are screened according to the screening conditions, so that the optimal value of the main bearing key design parameters is determined in the conceptual design stage of the engine, the friction loss of the main bearing is effectively reduced, and the thermal efficiency and the economical efficiency of the engine are effectively improved.

Referring to fig. 2, fig. 2 is a flowchart of a method for determining engine crankshaft parameters according to an embodiment of the present application, where the method includes:

S1, configuring key design parameters of different virtual main bearing models at different moments, and recording a set of key design parameters of the configured virtual main bearing models. In particular, the key design parameters of the virtual main bearing model include the diameter of the virtual main bearing model, the width of the virtual main bearing model. On the one hand, in order to meet the strength and rigidity requirements of the main bearing, the diameter and width of the main bearing cannot be designed to be too small; on the other hand, the main bearing diameter and width must not be too large in order to reduce friction losses. In general, the diameter and width of the main bearing are selected and defined in the engine concept design stage, and basically no design change occurs.

As an alternative embodiment, the key design parameters of different virtual main bearing models configured at different moments are recorded as a first combined set, which is specifically constructed according to the diameter and width combination of the main bearing of the engine, and specific operations include: and taking a plurality of numerical values according to a set tolerance within the range of the diameter of the main bearing of the engine to form a diameter array. And taking a plurality of numerical values according to a set tolerance within the range of the width of the main bearing of the engine to form a width array. And constructing a first combination set according to the diameter and width combinations formed by taking one value for each of the diameter number series and the width number series.

Illustratively, the main bearing diameters and widths in the first set of combinations are selected within the design choice in accordance with the 0.5mm arithmetic progression principle. For example, the main bearing diameter is selected in the range of 50mm to 60mm, and the width is selected in the range of 15mm to 25mm. The main bearing diameter is (60-50)/0.5+1=21, the bearing width is (25-15)/0.5+1=21, and the two combinations are 21×21=441, i.e. the first combination is 441.

S2, loading excitation is carried out on the virtual piston group model at different moments, the virtual piston group model makes reciprocating linear motion, the virtual connecting rod model is driven to make plane motion, the virtual connecting rod model drives the virtual crankshaft model to make rotary motion, and loads of the virtual main bearing model are detected respectively; wherein the excitation is derived from a true cylinder pressure curve during engine operation.

The engine is a power source of an automobile, the heat energy of fuel combustion is converted into mechanical energy, the crank-link mechanism is a main motion mechanism of the engine, and the crank-link mechanism is used for converting the reciprocating linear motion of the piston into the rotary motion of the crankshaft, and meanwhile, the acting force acting on the piston is converted into the torque output by the crankshaft to drive the automobile wheels to rotate. Thus, the virtual crank linkage model mimics the main motion of the engine: after the operation of S2 loading excitation is executed, the virtual crank connecting rod mechanism model simulates the real working state of the engine, so that the condition that the load is generated on the main bearing when the crank connecting rod mechanism moves in the output working state is outputted, and therefore, the load of the virtual main bearing model which is output by the S2 operation can be equivalent to the stress of the main bearing when the engine actually works.

In the following, it is explained in connection with fig. 3 to 5 how the excitation of the model loading of the virtual piston group is obtained on the basis of the actual cylinder pressure curve.

Fig. 3 is a schematic diagram of a crank-link mechanism according to an embodiment of the present application, as shown in fig. 3.

The piston 1 is connected to a small end of a connecting rod 3 via a piston pin 2, a large end of the connecting rod 3 is connected to a crank pin 7 of a crankshaft 5 via a connecting rod bearing 4, and a main bearing 8 is mounted on a main journal 6 of the crankshaft 5 and connected to an engine block 9.

When the engine works, heat energy generated by fuel combustion drives the crank-connecting rod mechanism to operate, and the specific process is as follows: the gas combustion pressure in the cylinder generated by the fuel combustion drives the piston 1 to do reciprocating rectilinear motion in the cylinder, the piston 1 doing reciprocating rectilinear motion drives the connecting rod 3 to do plane motion through the piston pin 2, the connecting rod 3 is in transmission connection with the crank pin 7 through the connecting rod bearing 4 to drive the crank shaft 5 to do rotary motion, wherein the load is applied to the main bearing 8 in the motion process of the crank connecting rod mechanism.

FIG. 4 is a schematic diagram of cylinder pressure curves in an embodiment of the present application, as shown in FIG. 4. The combustion pressure of the gas in the cylinder is usually determined by using a combustion analyzer test or a one-dimensional thermodynamic simulation analysis and other ways to obtain the change curves of the combustion pressure of the gas in the cylinder under different crank angles,Indicator diagram, i.e. cylinder pressure curve. The actual running condition of the engine is combined, different running speeds and different gas combustion pressures in the cylinder are adopted, so that the actual running speed range of the engine is covered, and a plurality of cylinder pressure curves are formed.

When the engine runs, the combustion pressure of gas in the cylinder is the motive power for the engine to do work outwards. When the in-cylinder gas combustion pressure shown in fig. 4 is applied to the piston 1 of the crank mechanism, the piston 1 is driven by the gas force F _g to reciprocate linearly with the reciprocating inertial force F _j, and therefore, the force acting on the crank mechanism is a gas force and a reciprocating inertial force.

Fig. 5 is a schematic diagram of a crank-link mechanism according to an embodiment of the application. The gas acting force acting on the top of the piston 1 and the in-cylinder gas combustion pressure satisfy the following equation:

Wherein F _g is gas acting force, p _g is gas combustion pressure in the cylinder, the unit is bar, D is cylinder diameter, Because the top of the piston is provided with a combustion chamber pit, the effective stress area of the piston adopts an empirical formula/>Obtained.

In this way, the gas acting force acting on the top of the piston 1 can be obtained from the in-cylinder gas combustion pressure arranged in the cylinder pressure curve and the effective force receiving area of the piston 1 by the above-described expression.

As described above, the top of the piston 1 receives the gas force and reciprocates in the cylinder in a straight line with the reciprocating inertial force. The crankshaft 5 in the crank mechanism is generally considered to be rotating at a constant speed, whereby the reciprocating inertial force satisfies the equation:

wherein F _j is the reciprocating inertial force, m _j is the reciprocating mass, ψ is the crank angle, r is the crank radius, and n is the engine speed.

Because the gas acting force and the reciprocating inertial force are collinear along the direction of the cylinder center line, as shown in fig. 5, the dotted line is the cylinder center line, and in the stress analysis process, for convenience of analysis, the piston pin center point 201 represents the connection of the small end of the connecting rod 3 with the piston 1 through the piston pin 2 and is used as the acting point of the load; the connecting rod 3 big end is connected with the crankshaft 5 through the connecting rod bearing 4 and is used as a load acting point by the crank pin center point 701; the main bearing is represented by main bearing center point 801 and serves as the point of action for the load. The combination of the gas force F _g and the reciprocating inertial force F _j is summarized as a simple algebraic sum, so that the force on the piston 1 during engine operation satisfies the equation:

the acting force is used as excitation for loading the virtual piston group model, the stress condition of the main bearing is analyzed, the stress condition is used for subsequent strength calculation, and the strength of the main bearing under the working conditions of all rotating speeds is ensured to meet the requirement.

In the following, with reference to fig. 6, it is explained how the load of the virtual main bearing model is detected when the excitation virtualization is loaded to the virtual piston group model.

Fig. 6 is a schematic diagram of spindle bearing force analysis according to an embodiment of the application. The piston 1 is in driving connection with the connecting rod 3 via the piston pin 2, and the force F acting on the piston 1 during engine operation is split at the piston pin centre point 201 into a lateral force F _cyl perpendicular to the cylinder axis and pressing the piston 1 against the cylinder wall, and a connecting rod force F _con acting on the connecting rod 3 along the axis of the connecting rod 3, wherein the pulling and pressing action refers to a stretching and compression action.

The connecting rod 3 is in driving connection with the crankshaft 5 via the crankpin 7, and the connecting rod force F _con is split at the crankpin centre point 701 into a tangential force F _τ perpendicular to the crank and a radial force F _k acting along the crank, the radial force F _k loading the main bearing 8.

Thus, according to the formula:

the main bearing 8 is subjected to load. From the above analysis, the main bearing 8 load satisfies the following expression:

Wherein F _mb is the main bearing load, p _g is the combustion pressure of gas in the cylinder, the unit is bar, D is the cylinder diameter, m _j is the reciprocating mass, r is the crank radius, n is the engine speed, ψ is the crank angle, and L is the connecting rod length.

Based on the above, in the virtual main bearing model, the gas acting force and the reciprocating inertia force obtained according to the cylinder pressure curve are transferred to the virtual main bearing model through the virtual piston group model, the virtual connecting rod model and the virtual crankshaft model, and the load output through the virtual main bearing model is the load generated on the virtual main bearing model when the virtual crankshaft model rotates, and can be equivalently the stress of the main bearing when the engine actually works.

It will be appreciated that in an alternative embodiment, performing the specific operation of S2 includes:

S201, combining the actual operation conditions of the engine, sequentially selecting cylinder pressure curves corresponding to different rotation speed conditions, and according to an arithmetic expression Determining a gas force acting on the piston top of the virtual piston group model;

wherein F _g is gas acting force, p _g is gas combustion pressure in a cylinder configured in a cylinder pressure curve, the unit is bar, D is cylinder diameter configured in a virtual crank-link mechanism model, The effective stress area of the piston is the virtual piston group model.

According to the formulaDetermining the reciprocating inertial force of the virtual piston group model;

Where F _j is a reciprocating inertial force, m _j is a reciprocating mass configured in the virtual crank mechanism model, ψ is a crank angle of the virtual crank mechanism model, r is a crank radius of the virtual crank mechanism model, and n is an engine speed configured in the virtual crank mechanism model.

S202, according to the formulaDetermining an excitation F for model loading of the virtual piston group;

Where F is excitation to be applied to the virtual piston group model, D is a cylinder diameter arranged in the virtual crank mechanism model, p _g is in-cylinder gas combustion pressure arranged in the cylinder pressure curve, n is an engine speed arranged in the virtual crank mechanism model, m _j is a reciprocating mass arranged in the virtual crank mechanism model, ψ is a crank angle of the virtual crank mechanism model, r is a crank radius of the virtual crank mechanism model, and n is an engine speed arranged in the virtual crank mechanism model.

S203, according to the formulaDetermining the load of the virtual main bearing model;

Wherein, F _mb is the load of the virtual main bearing model, F is the excitation of the virtual piston group model, ψ is the crank angle of the virtual crankshaft model, r is the crank radius of the virtual crankshaft model, and L is the connecting rod length of the virtual connecting rod model.

And S3, obtaining the strength of the virtual main bearing model according to the load of the virtual main bearing model and key design parameters of the virtual main bearing model, and determining the friction work of the virtual main bearing model.

In an alternative embodiment, performing S3 the specific operation of deriving the intensity of the virtual main bearing model comprises:

S301, determining an effective bearing area of the virtual main bearing model according to the formula a=d _mb·L_mb. Wherein D _mb is the diameter of the virtual main bearing model and L _mb is the width of the virtual main bearing model. The effective bearing area of the main bearing can be understood as the projected area, and the projected area obtained according to the product of the width and the diameter of the main bearing is the effective bearing area of the virtual main bearing model.

S302, according to the formulaDetermining that the intensity of the virtual main bearing model satisfies the formula/> Wherein σ _mb is the strength of the virtual main bearing model, MAX [ F _mb ] is the load maximum of the virtual main bearing model, and F _mb is the load of the virtual main bearing model. Because the number of the virtual main bearing models is multiple, each main bearing has one load output, and the maximum value in the load values of the main bearings is taken as the load output of the virtual main bearing models.

In an alternative embodiment, the operation of determining the friction work of the virtual main bearing model performed S3 is specifically:

S303, according to the formula And determining the oil film lubrication friction work of the virtual main bearing model.

S304, according to the formulaAnd determining the oil seal friction work of the virtual main bearing model.

S305, according to the formulaAnd determining the hydraulic loss friction work of the virtual main bearing model.

S306, determining the friction work of the virtual main bearing model according to the expression C _FMEP＝C_FMEP1+C_FMEP2+C_FMEP3.

Wherein, C _FMEP is the friction work of the virtual main bearing model, C _FMEP1 is the oil film lubrication friction work of the virtual main bearing model, C _FMEP2 is the oil seal friction work of the virtual main bearing model, and C _FMEP3 is the hydraulic loss friction work of the virtual main bearing model; c ₁ is an oil film lubrication friction power correction coefficient configured in the virtual main bearing model, C ₂ is an oil seal friction power correction coefficient configured in the virtual main bearing model, and C ₃ is a hydraulic loss friction power correction coefficient configured in the virtual main bearing model; mu' is an engine oil viscosity correction coefficient configured in the virtual crank-connecting rod mechanism model, n is an engine speed configured in the virtual crank-connecting rod mechanism model, D _mb is a diameter of the virtual main bearing model, L _mb is a width of the virtual main bearing model, n _mb is the number of the virtual main bearing models, D is a cylinder diameter configured in the virtual crank-connecting rod mechanism model, B is a piston stroke of the virtual piston group model, and i is the number of engine cylinders configured in the virtual crank-connecting rod mechanism model; the engine oil viscosity correction coefficient satisfies the formulaMu is the viscosity of the engine oil configured in the virtual crank-connecting rod mechanism model, mu ₀ is the standard value of the viscosity of the engine oil configured in the virtual crank-connecting rod mechanism model, and the viscosity of the engine oil is generally used for model calibration test data.

Specifically, the basis for obtaining the operation formula of S303 is: the main bearing adopts a pressure lubrication mode, and an oil film with enough thickness is formed on the friction surface of the main bearing. The oil film lubrication friction force of the main bearing satisfies the following formula:

F_f1＝f₁·F_n1

A＝D_mb·L_mb

Wherein F _f1 is the oil film lubrication friction force of the main bearing, F ₁ is the oil film lubrication friction coefficient, F _n1 is the normal acting force of the contact surface, V is the tangential relative speed of the contact surface, mu is the engine oil viscosity, A is the effective bearing area of the main bearing, n is the engine speed, D _mb is the diameter of the main bearing, and L _mb is the width of the main bearing.

The constant term is omitted, and for a certain main bearing, the oil film lubrication friction force of the main bearing meets the following formula:

When the constant term is omitted, the power output by all main bearing oil film lubrication friction forces, namely the main bearing oil film lubrication friction effective power, satisfies the following formula:

Wherein P _f1 is the effective lubrication friction power of the oil film of the main bearing, n is the engine speed, n _mb is the number of the main bearings, D _mb is the diameter of the main bearings, and L _mb is the width of the main bearings.

In engineering applications, average effective pressure (BMEP) is typically used to evaluate the utilization of the engine cylinder working volume, which is an important parameter in measuring the actual cycle power performance of an engine. The engine effective power and the average effective pressure satisfy the following formula:

Where P _me is the average effective pressure, P _e is the effective power of one working cycle of the engine, τ is the number of strokes, V _s is the working volume of the engine cylinder, i is the number of engine cylinders, D is the cylinder diameter, and B is the piston stroke.

Similar to the definition of mean effective pressure, the Friction Mean Effective Pressure (FMEP) defines the work lost per unit cylinder volume of the engine for one working cycle and can be used to measure the magnitude of the friction work. Therefore, the conversion formula of the effective lubrication friction power of the main bearing oil film and the average friction effective pressure FMEP1 is as follows:

Wherein FMEP1 is the average effective friction pressure of the main bearing oil film lubrication, P _f1 is the effective friction power of the main bearing oil film lubrication, n is the engine speed, V _s is the working volume of the engine cylinder, i is the number of engine cylinders, D is the cylinder diameter, B is the piston stroke, n _mb is the number of main bearings, D _mb is the diameter of the main bearings, and L _mb is the width of the main bearings.

Therefore, the oil film lubrication friction work of the virtual main bearing model is determined to satisfy the following formula:

Wherein, C _FMEP1 is oil film lubrication friction work of the virtual main bearing model, C ₁ is oil film lubrication friction work correction coefficient configured in the virtual main bearing model, μ' is oil viscosity correction coefficient configured in the virtual crank link mechanism model, μ is oil viscosity configured in the virtual crank link mechanism model, μ ₀ is oil viscosity standard value configured in the virtual crank link mechanism model, viscosity of engine oil is generally used for model calibration test data, D is cylinder diameter configured in the virtual crank link mechanism model, B is piston stroke of the virtual piston group model, i is number of engine cylinders configured in the virtual crank link mechanism model, n is engine rotational speed configured in the virtual crank link mechanism model, D _mb is diameter of the virtual main bearing model, L _mb is width of the virtual main bearing model, and n _mb is number of virtual main bearing models.

Specifically, the basis for obtaining the operation formula of S304 is:

The contact tension of the oil seal and the crankshaft can be approximately regarded as a constant value, and the friction force of the oil seal meets the following formula:

F_f2＝f₂·F_n2＝CONSTANT

omitting the constant term, the friction effective power of the main bearing oil seal meets the following formula:

P_f2∝F_f2·V∝n·D_mb

Wherein F _f2 is the oil seal friction force of the main bearing, F ₂ is the oil seal friction coefficient, F _n2 is the normal acting force of the contact surface, P _f2 is the effective friction power of the oil seal of the main bearing, V is the tangential relative speed of the contact surface, n is the engine speed, and D _mb is the diameter of the main bearing.

Similar to the definition of the average effective pressure, the conversion formula of the friction effective power of the main bearing oil seal and the friction average effective pressure FMEP2 is as follows:

Wherein FMEP2 is the average effective friction pressure of the main bearing oil seal, P _f2 is the effective friction power of the main bearing oil seal, n is the engine speed, V _s is the working volume of the engine cylinder, D is the diameter of the cylinder, B is the piston stroke, i is the number of engine cylinders, and D _mb is the diameter of the main bearing.

Therefore, the oil seal friction work of the virtual main bearing model is determined to satisfy the following formula:

Wherein, C _FMEP2 is the oil seal friction work of the virtual main bearing model, C ₂ is the oil seal friction work correction coefficient configured in the virtual main bearing model, D is the cylinder diameter configured in the virtual crank and connecting rod mechanism model, B is the piston stroke of the virtual piston group model, i is the number of engine cylinders configured in the virtual crank and connecting rod mechanism model, and D _mb is the diameter of the virtual main bearing model.

Specifically, the basis for obtaining the operation formula of S305 is:

according to the bernoulli theorem, omitting the constant term, the main bearing hydraulic loss work for a certain main bearing can be defined simply as:

W_h∝ρ·V²

Wherein W _h is the hydraulic loss work of the main bearing, ρ is the engine oil density, and V is the tangential relative speed of the contact surface.

In engineering applications, average effective pressure (BMEP) is generally used to evaluate the utilization of the working volume of an engine cylinder, and is an important parameter for measuring the actual cycle power performance of the engine. The effective power and average effective pressure of the engine satisfy the following formula:

/>

Where p _me is the average effective pressure, W _e is the effective work of one working cycle of the engine, V _s is the working volume of the engine cylinder, D is the cylinder diameter, and B is the piston stroke.

Similar to the definition of the average effective pressure, the conversion formula of the main bearing hydraulic loss work and the friction average effective pressure FMEP3 is as follows:

Wherein FMEP3 is the friction average effective pressure of the hydraulic loss of the main bearing, W _h is the hydraulic loss work of the main bearing, V _s is the working volume of the engine cylinder, D is the cylinder diameter, B is the piston stroke, n is the engine speed, i is the number of engine cylinders, n _mb is the number of main bearings, and D _mb is the diameter of the main bearing.

Therefore, determining the hydraulic lost friction work of the virtual main bearing model satisfies the following equation:

Wherein C _FMEP3 is hydraulic loss friction work of the virtual main bearing model, C ₃ is hydraulic loss friction work correction coefficient configured in the virtual main bearing model, D is cylinder diameter configured in the virtual crank mechanism model, B is piston stroke of the virtual piston group model, i is number of engine cylinders configured in the virtual crank mechanism model, n is engine speed configured in the virtual crank mechanism model, D _mb is diameter of the virtual main bearing model, and n _mb is number of virtual main bearing models.

In summary, performing the operation of operation S306 results in the friction work of the virtual main bearing model satisfying the following equation:

And S4, setting screening conditions according to the strength of the virtual main bearing model and the friction work of the virtual main bearing model, and determining the key design parameters of the virtual main bearing model meeting the screening conditions from the set of key design parameters of the virtual main bearing model.

As an alternative embodiment, the performing operation of S4 specifically includes:

S401, setting a first screening condition according to the intensity of the virtual main bearing model to obtain a first screening function, wherein the first screening condition is as follows: the strength of the virtual main bearing model is less than or equal to the yield strength of the virtual main bearing model.

S402, setting a second screening condition according to the friction work of the virtual main bearing model to obtain a second screening function, wherein the second screening condition is as follows: the friction work of the virtual main bearing model is minimal.

S403, determining the key design parameters of the virtual main bearing model meeting the first screening function and the second screening function from the set of key design parameters of the virtual main bearing model.

Based on the operations of S301 to S302 above, the operations of S401 are specifically:

Determining a first screening condition according to the formula sigma _mb≤σ_s; wherein σ _s is the yield strength of the virtual main bearing model; the yield strength represents the strength of the main bearing that must meet the yield limit of the material, which is determined by the material properties.

According to the formula sigma _mb≤σ_s Determining that the first screening function satisfies the algorithm/>

Therefore, the diameter and width of the virtual main bearing model must satisfy the formula:

Wherein D is a cylinder diameter configured in the virtual crank mechanism model, p _g is an in-cylinder gas combustion pressure configured in a cylinder pressure curve, its unit is bar, n is an engine speed configured in the virtual crank mechanism model, m _j is a reciprocating mass configured in the virtual crank mechanism model, ψ is a crank angle of the virtual crank mechanism model, r is a crank radius of the virtual crank mechanism model, L is a connecting rod length of the virtual connecting rod model, σ _s is a yield strength of the virtual main bearing model.

The strength of the main bearing is represented by acting force on the unit effective bearing area of the main bearing, the specific acting force F _mb of the main bearing is output through a virtual crank connecting rod mechanism model, and the effective bearing area A and the diameter and width of the main bearing can be converted by a formula, so that a relational expression of the strength of the main bearing and the diameter and width of the main bearing is obtained. Accordingly, the operation of S403 is performed, in which the first set of combinations of the diameter of the virtual main bearing model and the width of the virtual main bearing model is substituted into the first filter function, the diameter of the virtual main bearing model and the width of the virtual main bearing model satisfying the first filter condition are filtered out, and the second set of combinations is constructed.

Based on the operations of S303 to S306 above, the operations of S402 are specifically: according to the second screening condition, determining that the second screening function satisfies the formula: (D, L) =arg minC _FMEP(D_mb,L_mb); wherein, (D, L) is the combination of the diameter value and the width value of the virtual main bearing model when the friction work of the virtual main bearing model is minimum; c _FMEP is the friction work of the virtual main bearing model, D _mb is the diameter of the virtual main bearing model, and L _mb is the width of the virtual main bearing model. Accordingly, the operation of S403 is performed, the second combination set of the diameter of the virtual main bearing model and the width of the virtual main bearing model that satisfies the first screening condition is substituted into the second screening function, the diameter of the virtual main bearing model and the width of the virtual main bearing model that satisfy the second screening condition are screened out, the diameter and the width of the main bearing that minimize the friction work of the virtual main bearing model are obtained, and the key design parameters of the virtual main bearing are determined. The scheme is used as an optimal scheme, so that the intensity reliability of the main bearing meets the standard, the friction loss of the main bearing is effectively reduced, the friction power level of the main bearing is effectively improved, the diameter and the width of the main bearing of the optimal scheme are combined and substituted into the friction power calculation formula of the virtual main bearing model to obtain the friction power of the main bearing, and the optimal rapid evaluation of the friction loss of the main bearing and the selection of key design parameters of the main bearing are realized.

Based on the same inventive concept, the embodiment of the application also provides an engine crankshaft system parameter determining device, which is applied to a server, wherein the server is preconfigured with a virtual crank-connecting rod mechanism model 100 shown in fig. 1, the virtual crank-connecting rod mechanism model 100 comprises a virtual piston group model 101, a virtual connecting rod model 102, a virtual crankshaft model 103 and a virtual main bearing model 104, the virtual piston group model 101, the virtual connecting rod model 102 and the virtual crankshaft model 103 are sequentially connected in a transmission way, and the virtual main bearing model 104 is sleeved on a main journal of the virtual crankshaft model 103; as shown in fig. 7, the engine crankshaft system parameter determination device 700 includes:

A parameter configuration unit 701, configured to configure key design parameters of different virtual main bearing models at different moments, and record a set of key design parameters of the configured virtual main bearing models;

The detection unit 702 is configured to load excitation to the virtual piston set model at different moments, make the virtual piston set model perform reciprocating linear motion, drive the virtual connecting rod model to perform planar motion, and make the virtual connecting rod model drive the virtual crankshaft model to perform rotational motion, so as to respectively detect the load of the virtual main bearing model; wherein the excitation is obtained according to a real cylinder pressure curve when the engine is running;

A strength and friction work determining unit 703 for obtaining the strength of the virtual main bearing model according to the load of the virtual main bearing model and the key design parameters of the virtual main bearing model, and determining the friction work of the virtual main bearing model;

a screening unit 704 for setting screening conditions according to the intensity of the virtual main bearing model and the friction work of the virtual main bearing model, and determining key design parameters of the virtual main bearing model meeting the screening conditions from the set of key design parameters of the virtual main bearing model

Based on the same inventive concept, the embodiment of the application also provides a server; the server includes: the system comprises a memory, a processor and a computer program stored on the memory, wherein the computer program is configured to realize the steps of the engine crankshaft system parameter determining method in the specific embodiment when the computer program is called by the processor.

As shown in fig. 8, fig. 8 is a specific control flow chart for determining engine crankshaft parameters in the embodiment of the application, and the following control flow is implemented through the server: substituting a first combination set of diameter and width of a main bearing of a crankshaft system into a formula satisfied by a first screening functionScreening out a second combination set of the diameter and the width of the main bearing of the crankshaft system meeting the first screening condition, and substituting the second combination set into (D, L) =argmin C _FMEP(D_mb,L_mb) which is met by the second screening function to obtain the main bearing diameter and the width combination with the minimum friction work. The server realizes that the main bearing strength reliability requirement and friction power loss are balanced in the engine conceptual design stage, and reasonable main bearing diameter and width are selected, so that the friction loss of a crankshaft bearing is effectively reduced, and the thermal efficiency and the economical efficiency of the engine are effectively improved.

According to the application, through the application of the strength correlation formula and the friction work correlation formula, the calculation and judgment of the strength reliability and the friction work of the main bearing can be constructed aiming at different crankshaft systems, the optimal rapid evaluation of the friction loss of the main bearing is realized, the rapid selection of key design parameters of the main bearing is realized, the optimal key design parameters of the main bearing are obtained, and the design that the strength reliability of the main bearing meets the standard and the friction loss of the crankshaft is optimized is realized.

In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the application may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

Similarly, it should be appreciated that in the foregoing description of exemplary embodiments of the application, various features of the application are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. However, the disclosed solution should not be interpreted as reflecting the intention as follows: i.e., the claimed disclosure requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this disclosure.

It should be noted that the above-mentioned embodiments illustrate rather than limit the application, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The application may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by one and the same item of hardware. The use of the words first, second, third, etc. do not denote any order. These words may be interpreted as names.

Claims

1. The method is characterized by being applied to a server, wherein the server is preconfigured with a virtual crank-connecting rod mechanism model, the virtual crank-connecting rod mechanism model comprises a virtual piston group model, a virtual connecting rod model, a virtual crankshaft model and a virtual main bearing model, the virtual piston group model, the virtual connecting rod model and the virtual crankshaft model are sequentially connected in a transmission mode, and the virtual main bearing model is sleeved on a main journal of the virtual crankshaft model; the method comprises the following steps:

Configuring different key design parameters of the virtual main bearing model at different moments, and recording a set of the configured key design parameters of the virtual main bearing model;

Loading excitation to the virtual piston group model at different moments, wherein the virtual piston group model makes reciprocating linear motion to drive the virtual connecting rod model to make plane motion, and the virtual connecting rod model drives the virtual crankshaft model to make rotary motion to respectively detect the load of the virtual main bearing model; wherein the excitation is derived from a true cylinder pressure curve of the engine when running;

And setting screening conditions according to the strength of the virtual main bearing model and the friction work of the virtual main bearing model, and determining the key design parameters of the virtual main bearing model meeting the screening conditions from a set of key design parameters of the virtual main bearing model.

2. The engine crankshaft system parameter determining method according to claim 1, wherein the setting of the screening condition based on the strength of the virtual main bearing model and the friction work of the virtual main bearing model includes:

Determining key design parameters of the virtual main bearing model meeting the screening conditions from a set of key design parameters of the virtual main bearing model, comprising: and determining the key design parameters of the virtual main bearing model which meet the first screening function and the second screening function from the set of key design parameters of the virtual main bearing model.

3. The engine crankshaft system parameter determination method according to claim 2, wherein the key design parameters of the virtual main bearing model include a diameter of the virtual main bearing model, a width of the virtual main bearing model.

4. A method for determining parameters of an engine crankshaft as claimed in claim 3, wherein the obtaining the strength of the virtual main bearing model according to the load of the virtual main bearing model and the key design parameters of the virtual main bearing model includes:

According to the formula Determining that the intensity of the virtual main bearing model meets the formula/>

Wherein σ _mb is the strength of the virtual main bearing model, MAX [ F _mb ] is the maximum load value of the virtual main bearing model, and F _mb is the load of the virtual main bearing model.

5. The method for determining engine crankshaft parameters according to claim 4, wherein said setting a first screening condition according to the intensity of the virtual main bearing model to obtain a first screening function includes:

Determining the first screening condition according to the formula sigma _mb≤σ_s; wherein σ _s is the yield strength of the virtual main bearing model;

According to the formula sigma _mb≤σ_s, the formula Determining that the first screening function satisfies an algorithm

6. The method for determining engine crankshaft system parameters according to claim 4 or 5, wherein,

According to the formulaDetermining a load of the virtual main bearing model;

Wherein, F _mb is the load of the virtual main bearing model, F is the excitation of loading the virtual piston group model, ψ is the crank angle of the virtual crank model, r is the crank radius of the virtual crank model, and L is the connecting rod length of the virtual connecting rod model;

wherein F is excitation for loading the virtual piston group model, D is a cylinder diameter arranged in the virtual crank mechanism model, p _g is in-cylinder gas combustion pressure arranged in the cylinder pressure curve, n is an engine speed arranged in the virtual crank mechanism model, m _j is a reciprocating mass arranged in the virtual crank mechanism model, ψ is a crank angle of the virtual crank mechanism model, and r is a crank radius of the virtual crank mechanism model.

7. A method for determining engine crankshaft parameters according to claim 3, wherein said setting a second screening condition according to the friction work of the virtual main bearing model to obtain a second screening function includes:

Determining that the second screening function satisfies an equation according to the second screening condition: (D, L) =argmin C _FMEP(D_mb,L_mb);

Wherein, (D, K) is a combination of a diameter value and a width value of the virtual main bearing model when the friction work of the virtual main bearing model is minimum; c _FMEP is the friction work of the virtual main bearing model, D _mb is the diameter of the virtual main bearing model, and L _mb is the width of the virtual main bearing model.

8. The engine crankshaft system parameter determination method according to claim 7, wherein the detecting the friction work of the virtual main bearing model includes:

According to the formula Determining oil film lubrication friction work of the virtual main bearing model;

According to the formula Determining oil seal friction work of the virtual main bearing model;

According to the formula Determining the hydraulic loss friction work of the virtual main bearing model;

Wherein, C _FMEP is the friction work of the virtual main bearing model, C _FMEP1 is the oil film lubrication friction work of the virtual main bearing model, C _FMEP2 is the oil seal friction work of the virtual main bearing model, and C _FMEP3 is the hydraulic loss friction work of the virtual main bearing model; c ₁ is an oil film lubrication friction work correction coefficient configured in the virtual main bearing model, C ₂ is an oil seal friction work correction coefficient configured in the virtual main bearing model, and C ₃ is a hydraulic loss friction work correction coefficient configured in the virtual main bearing model; mu' is an engine oil viscosity correction coefficient configured in the virtual crank and connecting rod mechanism model, n is an engine speed configured in the virtual crank and connecting rod mechanism model, D _mb is a diameter of the virtual main bearing model, L _mb is a width of the virtual main bearing model, n _mb is the number of the virtual main bearing models, D is a cylinder diameter configured in the virtual crank and connecting rod mechanism model, B is a piston stroke of the virtual piston group model, and i is the number of engine cylinders configured in the virtual crank and connecting rod mechanism model; the engine oil viscosity correction coefficient satisfies the following formula And mu is the viscosity of the engine oil configured in the virtual crank-connecting rod mechanism model, and mu ₀ is the standard value of the viscosity of the engine oil configured in the virtual crank-connecting rod mechanism model.

9. The method for determining engine crankshaft system parameters according to claim 3, wherein,

The configuring key design parameters of different virtual main bearing models at different moments, recording a set of key design parameters of the configured virtual main bearing models, including:

configuring different diameters of the virtual main bearing models and widths of the virtual main bearing models at different moments, and recording a set of the configured diameters of the virtual main bearing models and widths of the virtual main bearing models;

Determining key design parameters of the virtual main bearing model satisfying the first screening function and the second screening function from the set of key design parameters of the virtual main bearing model, including:

Substituting the set of the diameter of the virtual main bearing model and the width of the virtual main bearing model into the first screening function, and screening out the set of the diameter of the virtual main bearing model and the width of the virtual main bearing model which meet the first screening condition;

Substituting a set of the diameter of the virtual main bearing model and the width of the virtual main bearing model which meet the first screening condition into the second screening function, and screening out the diameter of the virtual main bearing model and the width of the virtual main bearing model which meet the second screening condition.

10. The engine crankshaft system parameter determining device is characterized by being applied to a server, wherein a virtual crank connecting rod mechanism model is preconfigured on the server, the virtual crank connecting rod mechanism model comprises a virtual piston group model, a virtual connecting rod model, a virtual crankshaft model and a virtual main bearing model, the virtual piston group model, the virtual connecting rod model and the virtual crankshaft model are sequentially connected in a transmission mode, and the virtual main bearing model is sleeved on a main journal of the virtual crankshaft model; the device comprises:

the parameter configuration unit is used for configuring different key design parameters of the virtual main bearing model at different moments and recording a set of the configured key design parameters of the virtual main bearing model;

The detection unit is used for loading excitation to the virtual piston group model at different moments, the virtual piston group model performs reciprocating linear motion and drives the virtual connecting rod model to perform plane motion, and the virtual connecting rod model drives the virtual crankshaft model to perform rotary motion and respectively detects the load of the virtual main bearing model; wherein the excitation is derived from a true cylinder pressure curve of the engine when running;

The intensity and friction work determining unit is used for obtaining the intensity of the virtual main bearing model according to the load of the virtual main bearing model and key design parameters of the virtual main bearing model and determining the friction work of the virtual main bearing model;