Commercial vehicle dynamics modeling method considering transient excitation of power system

Abstract

The invention is suitable for the technical field of vehicle dynamics modeling and simulation, provides a commercial vehicle dynamics modeling method considering transient excitation of a power system, establishes a power transmission rotation dynamics quasi-transient model containing engine and transmission shaft excitation, further improves a riding dynamics model of a commercial vehicle, and improves the reliability of the commercial vehicle. And the coupling relationship between the power platform and the chassis platform is mainly analyzed. In addition, aiming at the key vibration conduction intermediate link of the frame, the invention constructs a rigid-flexible combined frame model. A final simulation result shows that the model can effectively simulate quality problems such as parking idling buffeting caused by power system excitation and structural resonance under various vehicle speeds in the acceleration process. The method has real-time performance and reliability, the transient effect of commercial vehicle power system excitation can be accurately expressed, the frequency domain response range of a commercial vehicle model is widened, and the vehicle abnormal buffeting problem is effectively managed and optimized through the virtual prototype simulation iteration technology.

Description

Technical Field

[0001] The invention belongs to the technical field of vehicle dynamics modeling and simulation, and in particular relates to a commercial vehicle dynamics modeling method considering transient excitation of a power system. Background Art

[0002] Vehicle jitter is a common and serious vibration phenomenon in commercial vehicles, which not only affects the steady-state performance of the vehicle, but may also cause a series of quality problems, such as parking, idling, and engine shutdown jitter, abnormal jitter at a certain speed, and knocking noise of the power system. Especially when the vehicle resonates, these negative phenomena will be aggravated, resulting in damage to the mechanical structure and components, and significantly affecting the driver's comfort and driving experience.

[0003] Compared with gasoline engines for passenger cars, diesel engines for commercial vehicles have higher power, greater torque, and lower speeds, which makes the excitation energy of their power systems stronger. During vehicle operation, due to the periodic reciprocating motion of translational parts such as pistons and connecting rods, and the periodic rotation of rotating parts such as cranks, balance shafts, and drive shafts, the excitation of the power system is continuous and produces a sweeping frequency effect as the vehicle speed changes. Therefore, continuous, periodic, high-energy, and sweeping frequency excitation of the power system is one of the important reasons for the vibration of commercial vehicles, especially when the excitation sweep frequency is consistent with the natural frequency of the commercial vehicle, it will cause severe resonance of the whole vehicle.

[0004] As the main carrier for automobile assembly and integration, the frame is responsible for connecting and supporting multiple components of the vehicle and is an important medium for the coupled resonance of various components of commercial vehicles. When the power system is working, its transient excitation is transmitted to the frame through multiple transmission paths (such as engine suspension, drive shaft intermediate support, etc.), and then the excitation is transmitted to other components through the connection stiffness and damping between the frame and various components, resulting in vehicle vibration quality problems.

[0005] At present, domestic commercial vehicles occasionally have quality problems such as severe idling and stalling and abnormal vibration at specific vehicle speeds. The main reason why these problems are difficult to cure is that the existing commercial simulation software cannot effectively simulate these negative phenomena, resulting in the inability of vehicle manufacturers to perform effective iterative optimization during the development process. The reason why commercial simulation software cannot simulate such quality problems is due to the inadequacy of its dynamic model: most commercial vehicle dynamic models only consider road excitation, but lack effective expression of power system excitation, and few have established a complete ride dynamics system model. At the same time, these models fail to reflect the coupling relationship between the rotational dynamics (Spin) and ride dynamics (Ride) between the power platform and the chassis platform. In addition, as an important flexible component, the frame model is mostly a low-order modal model, which mainly focuses on handling stability. The simulation frequency bandwidth is relatively narrow and cannot fully express the multi-order elastic modal effects. Therefore, it is difficult to simulate the wide-spectrum response of the actual frame within 100Hz, especially the flexible dynamic response of the medium and high frequencies, and cannot stimulate abnormal vibration negative phenomena such as resonance of the coupling between the power system and the frame. Summary of the invention

[0006] The object of the present invention is to provide a commercial vehicle dynamics modeling method taking into account transient excitation of a power system, aiming to solve the technical problems existing in the prior art identified in the background technology.

[0007] The present invention is implemented as follows: a commercial vehicle dynamics modeling method considering transient excitation of a power system, the method comprising:

[0008] S1. Establishing a vehicle dynamics model, wherein the vehicle dynamics model includes:

[0009] The ride dynamics system module is used to describe the movement of each component in the direction perpendicular to the XY plane of the intermediate coordinate system, that is, the movement in the vertical, roll and pitch directions, reflecting the ride comfort and driving experience of the vehicle;

[0010] Traction dynamics system module, used to describe the kinematic response of the powertrain;

[0011] A coupled impact module that describes the interaction between the ride dynamics system module and the traction dynamics system module;

[0012] S2, obtaining vehicle parameters and characteristics;

[0013] S3. Fill the vehicle parameters and characteristics obtained through measurement into the vehicle dynamics model and perform simulation verification.

[0014] As a further solution of the present invention, the ride dynamics system module includes:

[0015] Powertrain module, integrated axle module, rigid-flexible frame module, cab module and seat module, including:

[0016] The powertrain module is used to describe the Ride motion of the powertrain body relative to the frame. The formula for solving the Ride motion of the powertrain body is:

[0017]

[0018] in, Respectively represent the vertical velocity derivative, roll angular velocity derivative, and pitch angular velocity derivative of the powertrain body; Respectively represent the vertical total external force, roll total external moment, and pitch total external moment on the powertrain; m Eng , They represent the mass, roll inertia, and pitch inertia of the powertrain body relative to the body coordinate system;

[0019] The integral axle module is used to describe the Ride motion of the axle body relative to the frame. The Ride dynamics solution formula of the axle body is:

[0020]

[0021] in Respectively represent the vertical velocity derivative, roll angular velocity derivative, and pitch angular velocity derivative of the axle; Respectively represent the longitudinal velocity, lateral velocity, vertical velocity, roll angular velocity, pitch angular velocity, and yaw angular velocity of the frame; Respectively represent the vertical force, rolling moment and pitching moment acting on the axle; a Veh Represents the distance between the center of mass of the frame and the front axle; Represents the current vertical position of the axle relative to the frame; Respectively represent the K&C displacement correction of the axle center; m Axl The quality of the representatives

[0022] Rigid-flexible composite frame module, used to describe the low-frequency rigid body motion and high-frequency flexible body motion of the frame;

[0023] The cab module is used to describe the Ride motion of the cab body relative to the frame;

[0024] The seat module is used to describe the Ride motion of the seat relative to the cab, where the vertical motion formula of the seat body relative to the cab is:

[0025]

[0026] in, Respectively represent the longitudinal velocity, lateral velocity, roll angular velocity, pitch angular velocity, and yaw angular velocity of the seat body; Respectively represent the vertical velocity, roll angular velocity, and pitch angular velocity of the cab; Respectively represent the position coordinates of the seat body relative to the cab; They represent the K&C displacement correction of the seat body; Represents the seat suspension vertical force on the seat body; m Seat Represents the quality of the seat body.

[0027] As a further solution of the present invention, the traction dynamics system module comprises:

[0028] Quasi-transient engine module, clutch / torque converter module, gearbox module, drive shaft module and final drive and differential module, where:

[0029] Quasi-transient engine module, used to describe the excitation of engine combustion, including piston reciprocating motion, crank periodic rotation, balance shaft periodic rotation and torque fluctuation of overturning moment;

[0030] Solve the output torque of a single cylinder, then add the torques together to get the overall instantaneous output torque of the engine;

[0031] The calculation formula for the output torque of a single cylinder is:

[0032]

[0033] F PistnP1 =π(d PistnP1 / 2) 2 ·P PistnP1 (θ Crk1 )

[0034] in, is the output torque at the crank end; F PistnP1 is the pressure on the piston; L Crk1 is the crank length; L Rod1 is the connecting rod length; φ Crk1Ini is the initial installation angle of the crank; θ Crk1 is the current angle of the crank; d PistnP1 is the diameter of the piston; P PistnP1 (θ Crk1 ) is the function relationship curve between the cylinder pressure and the crank angle;

[0035] The transmission shaft module is used to describe the excitation of the transmission shaft during rotation, including the centrifugal force generated by the unbalanced radial mass distribution and the additional bending moment generated by the unequal speed of the cross-axis universal joint;

[0036] Among them, for front-engine rear-wheel drive, the formula for the centrifugal force component in the vertical direction of the drive shaft is:

[0037]

[0038] in, Represents the centrifugal force component in the vertical direction of the transmission shaft; m Sft Represents the centrifugal force component in the vertical direction of the transmission shaft; Represents the angular velocity of the transmission shaft; r SftCG Represents the offset of the center of mass of the transmission shaft; θ Sft Represents the rotation angle of the transmission shaft;

[0039] For a cross-axis universal joint with unequal speed characteristics, the torque change formula in the direction of rotation of the transmission shaft is:

[0040]

[0041] Respectively represent the rotational torque transmitted by the transmission shaft input shaft and the transmission shaft output shaft; β ΔSftAng Represents the angle between the input shaft and the output shaft of the transmission shaft; θ Sft1 Represents the rotation angle of the drive shaft input shaft; Represent the additional bending moments of the transmission shaft input shaft and the transmission shaft output shaft respectively.

[0042] As a further solution of the present invention, the obtaining of vehicle parameters and characteristics specifically includes:

[0043] Test the stiffness and damping characteristics of the seat suspension system under different excitation conditions to obtain the K&C characteristics of the seat location;

[0044] Test the power output characteristics of the engine under different working conditions and obtain the engine cylinder characteristics;

[0045] The natural frequency and vibration mode of the frame are obtained through modal analysis, and the dynamic flexible frame characteristics are obtained.

[0046] As a further solution of the present invention, the K&C characteristics of seat location selection are obtained, specifically:

[0047] The test is carried out in a way that the fixed seat drives the cab floor, and the response speed of the seat suspension system under different excitation conditions is recorded.

[0048] As a further solution of the present invention, the engine cylinder characteristics are obtained, specifically:

[0049] Set the environmental parameters, intake parameters, cylinder parameters, and exhaust parameters separately

[0050] Run the simulation and record the crank angle-in-cylinder pressure results.

[0051] As a further solution of the present invention, the vehicle parameters and characteristics obtained by measurement are filled into the vehicle dynamics model and simulated and verified, specifically including:

[0052] Simulate engine ignition and flameout conditions:

[0053] Simulate the impact of different flameout speeds on vehicle buffeting, and analyze the effects of stiffness and damping on buffeting;

[0054] Simulate vehicle driving conditions:

[0055] Reset the natural frequency, change the resonance speed, and avoid resonance in the commonly used vehicle speed range by adjusting the shift line position;

[0056] Perform drive train excitation analysis.

[0057] The beneficial effects of the present invention are:

[0058] This method is systematic and comprehensive. It establishes a complete commercial vehicle ride dynamics system including a rigid-flexible composite frame, seats, etc., and a commercial vehicle traction dynamic system that takes into account transient excitations such as the engine and drive shaft, and focuses on the coupling effect between the two.

[0059] The method is real-time and effective. Through the innovation and comparative verification of the modeling method and the model, it is shown that the present invention can simulate the quality problems of parking idle vibration and structural resonance at multiple vehicle speed points during acceleration. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 A flowchart of a commercial vehicle dynamics modeling method considering transient excitation of a power system provided by an embodiment of the present invention;

[0061] Figure 2 It is a schematic diagram of the powertrain and its suspension model;

[0062] Figure 3 It is a schematic diagram of the axle body model;

[0063] Figure 4 It is a schematic diagram of the seat and its suspension model;

[0064] Figure 5 It is a schematic diagram of a single cylinder model of an engine;

[0065] Figure 6 It is a single cylinder indicator diagram;

[0066] Figure 7 It is the instantaneous output torque diagram of the multi-cylinder engine;

[0067] Figure 8 It is a schematic diagram of radial deviation of the center of mass of the transmission shaft;

[0068] Fig. 9 This is a schematic diagram of the unequal speed of the cross-axis universal joint;

[0069] Fig.10 Schematic diagram of the coupling relationship between powertrain spin dynamics and vehicle ride dynamics.

[0070] Fig.11 This is a schematic diagram of the effect of vehicle Ride on the relative angles of multi-section transmission shafts;

[0071] Fig.12 This is a schematic diagram of the seat suspension K&C test;

[0072] Fig.13 The following are the MNF diagrams of the vehicle frame under different software environments;

[0073] Fig.14 The UniTruck parking vibration simulation comparison with different engine anti-drag torques - original ignition and flameout condition diagram;

[0074] Fig.15 The parking vibration simulation comparison of UniTruck with different powertrain mounts - the original ignition and flameout condition diagram;

[0075] Fig.16 UniTruck driving buffeting simulation condition - slow acceleration straight driving condition diagram;

[0076] Fig.17 Comparison of UniTruck driving vibration with different drive shafts - slow acceleration straight driving condition diagram;

[0077] Fig.18 Comparison of UniTruck driving vibration with different flexible frame natural frequencies - slow acceleration straight driving condition diagram;

[0078] Fig.19 Comparison of UniTruck driving vibration with different intermediate supports - slow acceleration straight driving condition diagram. DETAILED DESCRIPTION

[0079] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0080] It is understood that the terms "first", "second", etc. used in this application may be used herein to describe various elements, but unless otherwise specified, these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, without departing from the scope of this application, a first xx script may be referred to as a second xx script, and similarly, a second xx script may be referred to as a first xx script.

[0081] like Figure 1 As shown, the commercial vehicle dynamics modeling method considering transient excitation of the power system includes:

[0082] S1. Establishing a vehicle dynamics model, wherein the vehicle dynamics model includes:

[0083] Ride dynamics system module I is used to describe the movement of each component in the direction perpendicular to the XY plane of the intermediate coordinate system, that is, the movement in the vertical, roll and pitch directions, reflecting the ride comfort and driving experience of the vehicle;

[0084] The ride dynamics system module I describes the small movements of each component (including the axle, frame, powertrain, cab and seat, etc.) in the direction perpendicular to the XY plane of the intermediate coordinate system, that is, the movement in the vertical, roll and pitch directions. This module mainly reflects the ride comfort and driving experience of the vehicle. Among them, the vertical / roll / pitch high-frequency vibration mainly reflects the comfort of the vehicle, while the roll / pitch medium-frequency swing mainly reflects the driving feeling.

[0085] Traction dynamics system module II, traction dynamics system module II describes the motion response of the powertrain system (PowerTrain), which is a dynamic system with a single rotation direction. This invention mainly introduces the innovative parts of the quasi-transient engine module 2.1 and the transmission shaft module 2.4, and the rest of the models are similar to TruckSim;

[0086] The coupling influence module III is used to describe the interaction between the ride dynamics system module I and the traction dynamics system module II. The relationship between the spin dynamics of the powertrain and the ride dynamics of the vehicle is as follows: Fig.10 As shown;

[0087] The influence of power transmission Spin on the Ride of the whole vehicle is reflected in the following aspects: the transient overturning moment (reverse torque of output torque) excitation of the engine will act on the Ride of the powertrain; the centrifugal excitation force generated by the radial deviation of the center of mass of the drive shaft will be transmitted to the Ride of the frame through the intermediate support. If there is no actual intermediate support component, the centrifugal excitation force will be distributed and transmitted to the Ride of the powertrain and the Ride of the integral drive axle; the additional bending moment generated by the unequal speed characteristics of the cross-axis universal joint of the drive shaft will act on the connecting parts of the drive shaft, namely the Ride of the powertrain and the Ride of the integral drive axle; due to the change in the direction of the input and output torque of the drive axle, the longitudinal Spin torque of the drive shaft is changed to the lateral Spin torque of the wheel, so the drive axle will be subjected to the resulting overturning moment.

[0088] The influence of vehicle Ride on powertrain Spin is reflected in: Fig.11 As shown, due to the Ride movement of the powertrain and the integral drive axle (mainly vertical movement and pitch movement), the relative angles of the multi-section drive shafts will be affected, and then the spin torque fluctuations will be generated through the non-uniform speed characteristics of the cross-axis universal joints as shown in the formula for the transient change of torque in the rotation direction of the drive shaft.

[0089] S2, obtaining vehicle parameters and characteristics is the key to accurately obtaining vehicle parameters and characteristics to make the model accurate;

[0090] S3. Fill the vehicle parameters and characteristics obtained by measurement into the vehicle dynamics model and perform simulation verification. The present invention verifies the validity of the model by adjusting the vehicle parameters and characteristics related to power excitation in the UniTruck model, and proves the feasibility of improving vehicle negative phenomena based on model adjustment parameters.

[0091] In the present invention, the ride dynamics system module I comprises:

[0092] Powertrain module 1.1, integrated axle module 1.2, rigid-flexible frame module 1.3, cab module 1.4 and seat module 1.5, including:

[0093] The powertrain module 1.1 describes the Ride motion of the powertrain body relative to the frame. Since the powertrain suspension stiffness is high, the relative Ride motion between the powertrain body and the frame is small. Therefore, the Ride motion of the powertrain body can be solved by referring to the relevant theories of automobile vibration dynamics. Figure 2 And the following formula:

[0094]

[0095] in, Respectively represent the vertical velocity derivative, roll angular velocity derivative, and pitch angular velocity derivative of the powertrain body; Respectively represent the vertical total external force, roll total external moment, and pitch total external moment on the powertrain; m Eng , They represent the mass, roll inertia, and pitch inertia of the powertrain body relative to the body coordinate system;

[0096] The integrated axle module 1.2 describes the Ride motion of the axle body relative to the frame. Figure 3 The figure shows the schematic diagram of the axle model. The Ride dynamics solution of the axle is as follows:

[0097]

[0098] in Respectively represent the vertical velocity derivative, roll angular velocity derivative, and pitch angular velocity derivative of the axle; Respectively represent the longitudinal velocity, lateral velocity, vertical velocity, roll angular velocity, pitch angular velocity, and yaw angular velocity of the frame; Respectively represent the vertical force, rolling moment and pitching moment acting on the axle; a Veh Represents the distance between the center of mass of the frame and the front axle; Represents the current vertical position of the axle relative to the frame; Respectively represent the K&C displacement correction of the axle center; m Axl Quality of representation

[0099] The solution of the velocity and displacement of the axle body relative to the frame is similar to that of the powertrain body and will not be repeated here.

[0100] Rigid-flexible composite frame module 1.3, used to describe the low-frequency rigid body motion and high-frequency flexible body motion of the frame;

[0101] Cab module 1.4, used to describe the Ride motion of the cab body relative to the frame;

[0102] The seat module 1.5 describes the Ride motion of the seat relative to the cab. Since the seat mass accounts for a small proportion of the cab, the mass inertia of the seat can be included in the cab body when solving the cab motion. The cab motion obtained by solving represents the overall motion of the cab body and the seat body. The motion of the seat body itself is a secondary additional motion based on this overall motion. The seat and its suspension model are as follows: Figure 4 As shown, the vertical movement of the seat body relative to the cab is shown in the following formula.

[0103]

[0104] in, Respectively represent the longitudinal velocity, lateral velocity, roll angular velocity, pitch angular velocity, and yaw angular velocity of the seat body; Respectively represent the vertical velocity, roll angular velocity, and pitch angular velocity of the cab; Respectively represent the position coordinates of the seat body relative to the cab; They represent the K&C displacement correction of the seat body; Represents the seat suspension vertical force on the seat body; m Seat Represents the quality of the seat body.

[0105] In fact, the seat not only has vertical relative motion with respect to the cab, but also will be displaced in other directions due to the K&C geometric constraint characteristics of the seat suspension. For example, a "fork-arm" seat suspension may cause negative phenomena such as front and rear jumping when it vibrates vertically. In order to accurately simulate the quality problems caused by the seat and suspension, this seat model uses dynamic description of dynamics in the vertical direction, and K&C steady-state compensation in the other five directions. During K&C correction, the input is the vertical motion of the seat, and the output is the motion of the seat in the other five directions. The specific process will not be repeated here.

[0106] In the present invention, the traction dynamics system module II comprises:

[0107] Quasi-transient engine module 2.1, clutch / torque converter module 2.2, gearbox module 2.3, drive shaft module 2.4 and final reducer and differential module 2.5, wherein:

[0108] Quasi-transient engine module 2.1 describes the excitation during engine combustion, including piston reciprocating motion, crank periodic rotation, balance shaft periodic rotation, torque fluctuation of overturning moment, etc. For commercial vehicles, the number of engine cylinders is mostly 6 or more, and the excitation between cylinders will have a canceling effect. Therefore, for engines with more than 6 cylinders, only the torque fluctuation of overturning moment needs to be considered;

[0109] Solve the output torque of a single cylinder, then add the torques together to get the overall instantaneous output torque of the engine;

[0110] The engine model based on the cylinder indicator diagram can better express the transient output torque of the engine, as shown in the following formula and Figure 5 The output torque of a single cylinder is shown:

[0111]

[0112] F PistnP1 =π(d PistnP1 / 2) 2 ·P PitnP1 (θ Crk1 )

[0113] in, is the output torque at the crank end; F PistnP1 is the pressure on the piston; L Crk1 is the crank length; L Rod1 is the connecting rod length; φ Crk1Ini is the initial installation angle of the crank; θ Crk1 is the current angle of the crank; d PistnP1 is the diameter of the piston; P PistnP1 (θ Crk1 ) is the function curve of the cylinder pressure and crank angle, that is, Figure 6 As shown;

[0114] Solve the output torque of each cylinder, and then add the torques to get the overall instantaneous output torque of the engine, that is, Figure 7 As shown;

[0115] For the more common 4-cylinder engine of a passenger car, all the excitations of the above-mentioned engine need to be considered, which will not be elaborated in detail in this article.

[0116] The transmission shaft module 2.4 describes the excitation of the transmission shaft during rotation, including the centrifugal force generated by the unbalanced radial mass distribution and the additional bending moment generated by the unequal speed of the cross-axis universal joint.

[0117] Commercial vehicles are generally arranged in the form of front-engine rear-wheel drive. The size and mass of the drive shaft are large, and its processing accuracy and assembly error are also large. Therefore, it is easy to produce radial deviation of the center of mass, which in turn brings about centrifugal force excitation of imbalance, as shown in the following formula and Figure 8 As shown:

[0118]

[0119] in, Represents the centrifugal force component in the vertical direction of the transmission shaft; m Sft Represents the centrifugal force component in the vertical direction of the transmission shaft; Represents the rotational angular velocity of the transmission shaft; r SftCG Represents the offset of the transmission shaft mass center; θ Sft Represents the rotation angle of the transmission shaft;

[0120] Commercial vehicles often use cross-axis universal joints with unequal speed characteristics. The resulting torque transient changes in the direction of rotation of the transmission shaft are as follows: Fig. 9 As shown:

[0121]

[0122] Respectively represent the rotational torque transmitted by the transmission shaft input shaft and the transmission shaft output shaft; βΔSftAng Represents the angle between the input shaft and the output shaft of the transmission shaft; θ Sft1 Represents the rotation angle of the drive shaft input shaft; Represent the additional bending moments of the transmission shaft input shaft and the transmission shaft output shaft respectively.

[0123] In the present invention, the vehicle parameters and characteristics are obtained, and there are two kinds of K&C tests for seat suspension, "fixed seat driving cab floor" and "fixed cab floor driving seat", respectively. Fig.12 -a, Fig.12 This article recommends the use of the "fixed seat drive cab floor" K&C test method, and the specific test plan is shown in Table 1.

[0124] Table 1 Seat suspension K&C test plan

[0125]

[0126] The dynamometer characteristics of the engine cylinder can be obtained through engine bench testing or through engineering software modeling and simulation. The former method will not be described in detail. This article takes GT-Suite software as an example to briefly introduce the specific operation steps:

[0127] 1. Environmental parameter settings: Set the external environment pressure and temperature as well as air medium properties.

[0128] 2. Intake parameter settings. For the intake port and intake pipe, set their respective size parameters, physical properties such as pipe wall material and friction coefficient, wall temperature, and gas state; set the size parameters, clearance, lift curve, and forward and reverse flow coefficient curves under different lifts of the intake valve. 3. Cylinder parameter settings. Set the cylinder wall temperature, heat transfer model and other parameters; set the number of strokes, select the speed characteristics and set the speed characteristic attribute parameters; set the crankshaft geometry parameters and clearance; set the ignition order.

[0129] 4. Exhaust parameter setting: Similar to step 2.

[0130] 5. Simulation output. Open the piston model, select the output variable "crank angle-cylinder pressure", click simulation run and save the results.

[0131] The soft body properties of the frame can be obtained through the MNF modal neutral file. Taking HyperMesh software as an example, the basic operation steps are briefly described:

[0132] 1. Create a tab. Perform basic operations of finite element analysis, such as importing geometry, dividing the mesh, setting material properties, setting feature cards, assigning mesh material properties, etc. Select CMS METH (modal synthesis method) in Load Collectors to create a load file, select METHOD as CB in the file properties, and set it as a constrained mode. Create rigid constraints in Load Collectors, establish six-degree-of-freedom rigid constraint nodes in space, and establish a rigid constraint range based on the spider web method. Create line elements and only output the outline to avoid MNF being too large.

[0133] 2. Simulation settings. In the Analysis control cards, select

[0134] Set GLOBAL_CASE_CONTROL to CMSMETH, select output as ADAMSMNF, and select the line element created for output in MODEL.

[0135] 3. Output results. Select the solver for analysis and output the MNF file. The results are as follows: Fig.13 shown.

[0136] For the simulation verification of step S3:

[0137] The vehicle's original ignition and flameout conditions are simulated. By adjusting the engine's anti-drag torque characteristic table, the engine speed is reduced to zero at different rates when the engine is turned off. The vibration condition of the commercial vehicle is observed, such as Fig.14 shown.

[0138] Simulate the vehicle's in-situ ignition and shutdown conditions, and adjust the stiffness and damping of the engine mount to see if the quality problems of vehicle vibration can be eliminated or reduced, such as Fig.15 shown.

[0139] like Fig.14 -b, when the engine is running, the powertrain will be subject to high-frequency excitation force (derived from the reaction force of the engine's transient output torque). During the vehicle shutdown process, as the engine speed decreases, the excitation force acts on the engine body in the form of a sweep frequency and is transmitted to the entire vehicle through the flexible frame, causing abnormal vibrations in various vehicle components, such as Fig.14 -c. Fig.15 As shown, adjusting the parameters of the powertrain mount can affect the vehicle vibration intensity when the engine is working normally (see Fig.15 -d, but has limited impact on the vibration when the engine is turned off. To avoid the quality problem of abnormal vibration of the vehicle when the engine is turned off, it is still necessary to start with the "engine speed zeroing speed", such as Fig.14 As shown in d to f.

[0140] Simulate the vehicle's slow acceleration and straight-line driving conditions, adjust relevant vehicle parameters, and observe the vibration of the commercial vehicle. Figures 16 to 19 shown.

[0141] like Fig.16 As shown in Figure 1, when the vehicle is running, the radial unbalanced mass of the transmission shaft will generate a centrifugal excitation force. As the vehicle speed increases, the excitation force is transmitted to the vehicle in the form of a sweep frequency, causing the vehicle to produce abnormal vibration at a certain speed, such as Fig.17 shown.

[0142] Fig.18 It is shown that by adjusting the natural frequency parameters of the flexible frame, the corresponding vehicle speed at resonance will shift. Based on this, the resonant vehicle speed can be transferred to an uncommon speed range by adjusting the shift line to reduce the negative impact of driving vibration. Fig.19 It is shown that adjusting the parameters of the intermediate support can significantly reduce the vehicle vibration caused by the drive shaft excitation. Based on this, such quality problems can be reduced by adding an intermediate support device to the vehicle.

[0143] In summary, it is proved that this model can simulate the quality problems of parking idle vibration and abnormal vibration at a certain vehicle speed induced by power system excitation.

[0144] It should be understood that, although each step in the flow chart of each embodiment of the present invention is shown in sequence according to the indication of the arrow, these steps are not necessarily performed in sequence according to the order indicated by the arrow. Unless there is a clear explanation in this article, the execution of these steps does not have a strict order restriction, and these steps can be performed in other orders. Moreover, at least a portion of the steps in each embodiment may include a plurality of sub-steps or a plurality of stages, and these sub-steps or stages are not necessarily performed at the same time, but can be performed at different times, and the execution order of these sub-steps or stages is not necessarily performed in sequence, but can be performed in turn or alternately with at least a portion of other steps or sub-steps or stages of other steps.

[0145] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0146] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

[0147] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A commercial vehicle dynamics modeling method considering transient excitation of the power system, characterized in that: The method comprises: S1. Establishing a vehicle dynamics model, wherein the vehicle dynamics model includes: The ride dynamics system module is used to describe the movement of each component in the direction perpendicular to the XY plane of the intermediate coordinate system, that is, the movement in the vertical, roll and pitch directions, reflecting the ride comfort and driving experience of the vehicle; Traction dynamics system module, used to describe the kinematic response of the powertrain; A coupled impact module, which is used to describe the interaction between the ride dynamics system module and the traction dynamics system module; S2, obtaining vehicle parameters and characteristics; S3. Fill the vehicle parameters and characteristics obtained through measurement into the vehicle dynamics model and perform simulation verification.

2. The method according to claim 1, characterized in that The ride dynamics system module includes: Powertrain module, integrated axle module, rigid-flexible frame module, cab module and seat module, including: The powertrain module is used to describe the Ride motion of the powertrain body relative to the frame. The formula for solving the Ride motion of the powertrain body is: in, Respectively represent the vertical velocity derivative, roll angular velocity derivative, and pitch angular velocity derivative of the powertrain body; Respectively represent the vertical total external force, roll total external moment, and pitch total external moment on the powertrain; m Eng , They represent the mass, roll inertia, and pitch inertia of the powertrain body relative to the body coordinate system; The integral axle module is used to describe the Ride motion of the axle body relative to the frame. The Ride dynamics solution formula of the axle body is: in Respectively represent the vertical velocity derivative, roll angular velocity derivative, and pitch angular velocity derivative of the axle; Respectively represent the longitudinal velocity, lateral velocity, vertical velocity, roll angular velocity, pitch angular velocity, and yaw angular velocity of the frame; Respectively represent the vertical force, rolling moment and pitching moment acting on the axle; a Veh Represents the distance between the center of mass of the frame and the front axle; Represents the current vertical position of the axle relative to the frame; Respectively represent the K&C displacement correction of the axle center; m Axl The mass rigid-flexible composite frame module represented by the vehicle is used to describe the low-frequency rigid body motion and high-frequency flexible body motion of the frame; The cab module is used to describe the Ride motion of the cab body relative to the frame; The seat module is used to describe the Ride motion of the seat relative to the cab, where the vertical motion formula of the seat body relative to the cab is: in, Respectively represent the longitudinal velocity, lateral velocity, roll angular velocity, pitch angular velocity, and yaw angular velocity of the seat body; Respectively represent the vertical velocity, roll angular velocity, and pitch angular velocity of the cab; Respectively represent the position coordinates of the seat body relative to the cab; They represent the K&C displacement correction of the seat body; Represents the seat suspension vertical force on the seat body; m Seat Represents the quality of the seat body.

3. The method according to claim 2, characterized in that The traction dynamics system module includes: Quasi-transient engine module, clutch / torque converter module, gearbox module, drive shaft module and final drive and differential module, where: Quasi-transient engine module, used to describe the excitation of engine combustion, including piston reciprocating motion, crank periodic rotation, balance shaft periodic rotation and torque fluctuation of overturning moment; Solve the output torque of a single cylinder, then add the torques together to get the overall instantaneous output torque of the engine; The calculation formula for the output torque of a single cylinder is: F PistnP1 =π(d PistnP1 / 2) 2 ·P PistnP1 (i Crk1 ) in, is the output torque at the crank end; F PistnP1 is the pressure on the piston; L Crk1 is the crank length; L Rod1 is the connecting rod length; φ Crk1Ini is the initial installation angle of the crank; θ Crk1 is the current angle of the crank; d PistnP1 is the diameter of the piston; P PistnP1 (θ Crk1 ) is the function relationship curve between the cylinder pressure and the crank angle; The transmission shaft module is used to describe the excitation of the transmission shaft during rotation, including the centrifugal force generated by the unbalanced radial mass distribution and the additional bending moment generated by the unequal speed of the cross-axis universal joint; Among them, for front-engine rear-wheel drive, the formula for the centrifugal force component in the vertical direction of the drive shaft is: in, Represents the centrifugal force component in the vertical direction of the transmission shaft; m Sft Represents the centrifugal force component in the vertical direction of the transmission shaft; Represents the angular velocity of the transmission shaft; r SftCG Represents the offset of the center of mass of the transmission shaft; θ Sft Represents the rotation angle of the transmission shaft; For a cross-axis universal joint with unequal speed characteristics, the torque change formula in the direction of rotation of the transmission shaft is: Respectively represent the rotational torque transmitted by the transmission shaft input shaft and the transmission shaft output shaft; β ΔSftAng Represents the angle between the input shaft and the output shaft of the transmission shaft; θ Sft1 Represents the rotation angle of the drive shaft input shaft; Represent the additional bending moments of the transmission shaft input shaft and the transmission shaft output shaft respectively.

4. The method according to claim 1, characterized in that: The obtaining of vehicle parameters and characteristics specifically includes: Test the stiffness and damping characteristics of the seat suspension system under different excitation conditions to obtain the K&C characteristics of the seat location; Test the power output characteristics of the engine under different working conditions and obtain the engine cylinder characteristics; The natural frequency and vibration mode of the frame are obtained through modal analysis, and the dynamic flexible frame characteristics are obtained.

5. The method according to claim 4, characterized in that The K&C characteristics of seat location are obtained, specifically: The test is carried out in a way that the fixed seat drives the cab floor, and the response speed of the seat suspension system under different excitation conditions is recorded.

6. The method according to claim 4, characterized in that The obtaining of the engine cylinder characteristics is specifically: Set the environmental parameters, intake parameters, cylinder parameters, and exhaust parameters separately Run the simulation and record the crank angle-in-cylinder pressure results.

7. The method according to claim 1, characterized in that The vehicle parameters and characteristics obtained by measurement are filled into the vehicle dynamics model and simulated and verified, specifically including: Simulate engine ignition and flameout conditions: Simulate the impact of different flameout speeds on vehicle buffeting, and analyze the effects of stiffness and damping on buffeting; Simulate vehicle driving conditions: Reset the natural frequency, change the resonance speed, and avoid resonance in the commonly used vehicle speed range by adjusting the shift line position; Perform drive train excitation analysis.

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