A method and system for auxiliary development of powertrain suspension system

Abstract

The invention relates to a method and system for auxiliary development of a powertrain suspension system, belonging to the technical field of automobile NVH analysis, and capable of analyzing the powertrain suspension system from multiple aspects, with accurate and reliable analysis results, thereby providing a basis and guidance for the development of the powertrain suspension system; the method comprises: importing powertrain suspension system parameters and hydraulic suspension parameters with a specific template; converting suspension system parameter coordinates into standard coordinate system coordinates; dynamically analyzing suspension system parameters using 6-DOF and 13-DOF models to obtain decoupling rates of various modes and directions, transient response data under different initial conditions, acceleration data at a certain point, and frequency response data in various directions; statically analyzing suspension system parameters under 29 working conditions; calculating unmeasurable parameters and dynamic characteristic data of hydraulic suspension according to easily measurable parameters and information of hydraulic suspension; and optimizing parameters to optimize the stiffness and installation angle of the suspension system.

Description

Technical Field

[0001] The present invention relates to the technical field of automobile NVH analysis, and in particular to a method and system for auxiliary development of a powertrain suspension system. Background Art

[0002] In recent years, the rapid development of automobile technology has attracted wide attention to the NVH performance of automobiles. The traditional suspension development process requires repeated adjustments, tests, and readjustments, which is time-consuming and labor-intensive. It is obviously not applicable in today's world where all manufacturers are striving for efficiency and speed. Therefore, it is necessary to have an efficient, easy-to-operate, and widely applicable powertrain suspension system auxiliary development idea and method.

[0003] The six-degree-of-freedom (6-DOF) model is now widely used in the vibration analysis of the powertrain suspension system. The six-DOF model approximately assumes that the vehicle body mass is infinite and the powertrain is connected to the ground through the suspension. However, with the development of automobile technology, the vehicle body has become lighter and lighter, and the error caused by this approximate grounding has become larger and larger. Therefore, the model needs to be optimized in a direction that is closer to reality.

[0004] Therefore, it is necessary to study a method for auxiliary development of a powertrain suspension system to address the deficiencies of the prior art and to solve or alleviate one or more of the above problems. Summary of the invention

[0005] In view of this, the present invention provides a method and system for auxiliary development of a powertrain suspension system, which can analyze the powertrain suspension system from multiple aspects, and the analysis results are accurate and reliable, providing a basis and guidance for the development of the powertrain suspension system.

[0006] In one aspect, the present invention provides a method for auxiliary development of a powertrain suspension system, the method comprising:

[0007] Data input: Acquire known parameter data and import them with a specific template to facilitate subsequent processing; the parameter data include powertrain mount system parameters and hydraulic mount parameters; the hydraulic mount parameters refer to measurable and easy-to-measure hydraulic mount parameters;

[0008] Coordinate conversion: determining whether the powertrain suspension system parameters belong to the coordinate parameters of the standard coordinate system, and if not, converting the coordinates into the coordinates of the standard coordinate system;

[0009] Dynamic analysis: Dynamic analysis of the powertrain suspension system parameters in the standard coordinate system; dynamic analysis using a 6-degree-of-freedom model of the suspension system grounded and / or a 13-degree-of-freedom model of the vehicle; dynamic analysis includes modal analysis, harmonic response analysis and transient response analysis; the results of the dynamic analysis include: decoupling rates of each order mode and each direction, transient response data under different initial conditions and acceleration data of a certain point, and frequency response data in each direction;

[0010] Static analysis: static analysis is performed on the parameters of the powertrain mounting system in the standard coordinate system; the results of the static analysis include: the analysis results of the traditional 28 working conditions of the powertrain mounting system under different stiffness input forms and the analysis results of the powertrain mounting system under custom working conditions; the custom working conditions are adjusted by changing the magnitude and direction of the force;

[0011] Hydraulic mount analysis: calculating unmeasurable parameters of the hydraulic mount according to the hydraulic mount parameters, and calculating dynamic characteristic data of the hydraulic mount according to the unmeasurable parameters and the hydraulic mount parameters.

[0012] According to the above aspects and any possible implementation, an implementation is further provided, wherein the method further comprises, before the dynamic analysis:

[0013] Adjustment and optimization: Determine whether the powertrain suspension system parameters in the standard coordinate system meet the decoupling layout standards and optimization standards. If not, make adjustments and optimizations.

[0014] According to the above aspects and any possible implementation, there is further provided an implementation, wherein the unmeasurable parameters of the hydraulic mount include upper liquid chamber volume stiffness, equivalent piston area and local loss coefficient.

[0015] According to the above aspects and any possible implementation, there is further provided an implementation, wherein the standard coordinate system is a powertrain mass center coordinate system;

[0016] The coordinate transformation matrix is ​​used to realize the conversion between coordinates in different coordinate systems.

[0017] According to the above aspects and any possible implementation, an implementation is further provided, wherein the adjustment and optimization includes:

[0018] Deterministic optimization, so that the optimized system natural frequency and decoupling rate reach the required range;

[0019] and robustness optimization, so that the robustness of the optimized system reaches the required range;

[0020] The deterministic optimization and the robust optimization are both implemented using genetic algorithms, and the stiffness and installation angle of the suspension system are optimized by setting an objective function, setting upper and lower limits after optimization, and limiting the number of optimizations.

[0021] According to the aspects and any possible implementation methods described above, an implementation method is further provided, wherein the content of the harmonic response analysis includes: using excitation signals of different frequencies to act on the powertrain, taking the frequency of the excitation signal as the horizontal axis variable, taking the ratio of the amplitude of the powertrain in different directions to the amplitude of the excitation signal as the vertical axis variable, and drawing a vibration frequency response curve to reflect the sensitive range of the powertrain suspension system to the excitation frequency.

[0022] According to the above aspects and any possible implementation, an implementation is further provided, in which the decoupling rate of the degree of freedom k under the i-th order modal vibration is calculated as follows:

[0023]

[0024] in,

[0025] In the formula, m kl represents the kth row and lth column element in the mass matrix, ω i is the i-th order natural circular frequency, and are the values ​​of k and l degrees of freedom in the i-th order modal vector corresponding to the i-th order natural circular frequency, respectively, c i is a multiple value (the modal vector is normalized during calculation, that is, each element in the modal vector of the same order is divided by a number at the same time so that the largest element becomes 1), and i is a positive integer.

[0026] According to the above aspects and any possible implementation, an implementation is further provided, wherein the static analysis includes: storing the stress conditions of 29 working conditions in a 6*1*29 three-dimensional matrix, calculating the stiffness matrix under the static stiffness value, and calculating the displacement of the system in each direction according to the generalized Hooke's law; the expression is as follows:

[0027] F=KX

[0028] In the formula, F represents the force of the powertrain, K represents the suspension stiffness, and X represents the displacement of the powertrain, all of which are generalized physical quantities.

[0029] According to the above aspects and any possible implementation, there is further provided an implementation, wherein the powertrain suspension system parameter includes a suspension inclination angle;

[0030] The input method of the suspension inclination angle is the Euler angle input method or the coordinate axis angle input method;

[0031] The specific method of inputting Euler angles is as follows: when the u, v, and w axes of the main stiffness axis coordinate system of the mount are in the same direction as the x, y, and z axes of the standard coordinate system, the input Euler angle is (0, 0, 0); when the u axis is in the same direction as the x axis of the powertrain center of mass coordinate system and the three-way main stiffness axis coordinate system of the mount is only rotated around the u axis by an angle sita, the input Euler angle is (0, sita, 0);

[0032] The specific method of inputting the coordinate axis angle is: input the angles between the u, v, w axes of the main stiffness axis coordinate system of the suspension and the x, y, z axes of the standard coordinate system respectively; the data of this input method is used for dynamic analysis and static analysis.

[0033] In another aspect, the present invention provides a system for assisting development of a powertrain suspension system, the system comprising:

[0034] Data input module: used to obtain known parameter data and import it with a specific template for subsequent processing; the parameter data includes powertrain suspension system parameters and hydraulic suspension parameters;

[0035] Coordinate conversion module: used to determine whether the powertrain suspension system parameters belong to the coordinate parameters of the standard coordinate system, and if not, convert the coordinates into the coordinates of the standard coordinate system;

[0036] Dynamic analysis module: used to dynamically analyze the parameters of the powertrain suspension system in the standard coordinate system; adopt the 6-degree-of-freedom model of the suspension system grounded and / or the 13-degree-of-freedom model of the whole vehicle for dynamic analysis; the dynamic analysis module includes a modal analysis module, a harmonic response analysis module and a transient response analysis module; the output results of the dynamic analysis module include: decoupling rates of each order mode and each direction, transient response data under different initial conditions and acceleration data of a certain point, and frequency response data in each direction;

[0037] Static analysis module: used to perform static analysis on the parameters of the powertrain mounting system in the standard coordinate system; the output results of the static analysis module include: the analysis results of the traditional 28 working conditions of the powertrain mounting system under different stiffness input forms and the analysis results of the powertrain mounting system under the custom working conditions; the custom working conditions are adjusted by changing the magnitude and direction of the force;

[0038] The hydraulic mount analysis module is used to calculate the unmeasurable parameters of the hydraulic mount according to the hydraulic mount parameters, and calculate the dynamic characteristic data of the hydraulic mount according to the unmeasurable parameters and the hydraulic mount parameters.

[0039] Compared with the prior art, one of the above technical solutions has the following advantages or beneficial effects: the present invention can convert different coordinate systems into a standard coordinate system through coordinate conversion, meeting the requirements of multi-party cooperation that cannot be avoided during automobile development, so that each partner can carry out their own development work according to their own optimal coordinate system, and then use the method of the present invention to perform conversion to achieve further auxiliary analysis;

[0040] Another technical solution in the above technical solution has the following advantages or beneficial effects: the present invention optimizes the parameters, which can optimize the suspension stiffness value in the parameters and the installation angle of the suspension, so that the analysis result is more accurate and reliable;

[0041] Another technical solution in the above technical solution has the following advantages or beneficial effects: the dynamic analysis of the present invention can be based on either a 6-DOF model or a 13-DOF model. In the past, the 6-DOF model was mostly used. Since the 13-DOF model is very complex, it is not widely used. However, writing it into the software reduces its complexity. The developer only needs to fill in the parameters as required. The analysis result obtained by the 13-DOF model is better.

[0042] Another technical solution in the above technical solution has the following advantages or beneficial effects: the static analysis of the present invention, in addition to performing static analysis under the general 28 working conditions, can also customize a working condition for static analysis, which increases the analysis dimension of static analysis, has wider applicability, and more accurate analysis results;

[0043] Another technical solution of the above technical solution has the following advantages or beneficial effects: the present invention obtains other parameters that cannot be directly measured by experiment and characteristic data of the hydraulic mount through known and measurable hydraulic mount parameters, thereby realizing analysis of the hydraulic mount and providing guidance for actual development work;

[0044] Another technical solution among the above technical solutions has the following advantages or beneficial effects: the present invention adopts two methods, namely Euler angle input and coordinate axis angle input, to realize the input of the suspension inclination angle, and the input method is more comprehensive.

[0045] Of course, any product implementing the present invention does not necessarily need to achieve all of the above-mentioned technical effects at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0047] Figure 1 is a flow chart of a powertrain suspension system auxiliary development method provided by one embodiment of the present invention;

[0048] Figure 2 It is a schematic diagram of a whole vehicle model and a coordinate system provided by an embodiment of the present invention;

[0049] Figure 3 1 is a three-view diagram of a torque shaft provided by an embodiment of the present invention;

[0050] Figure 4 1 is a harmonic response curve diagram of an unbalanced reciprocating inertial force provided by an embodiment of the present invention; wherein (a) is a displacement amplitude curve diagram, and (b) is an angle amplitude curve diagram;

[0051] Figure 5 1 is a harmonic response curve diagram of an unbalanced overturning torque provided by an embodiment of the present invention; wherein (a) is a displacement amplitude curve diagram, and (b) is an angle amplitude curve diagram;

[0052] Figure 6 1 is a transient analysis result diagram of a 6-DOF model when the initial condition is not 0, provided by an embodiment of the present invention; wherein (a) is a displacement transient response diagram, and (b) is an angle transient response diagram;

[0053] Figure 7 1 is a vibration curve diagram of a powertrain in various directions in a vehicle coordinate system provided by an embodiment of the present invention; wherein (a) no excitation force in the RY direction is added, and (b) an excitation force in the RY direction is added;

[0054] Figure 8 is a three-dimensional acceleration curve diagram at a vehicle body measurement point provided by an embodiment of the present invention;

[0055] Fig. 9 1 is a stiffness curve diagram of each main axis of three suspensions provided by an embodiment of the present invention; wherein (a), (b), and (c) are stiffness curve diagrams of the first suspension, the second suspension, and the third suspension on each main axis, respectively;

[0056] Fig.10 It is a dynamic characteristic parameter curve diagram provided by an embodiment of the present invention; wherein, (a) is a dynamic stiffness curve diagram, (b) is an energy storage dynamic stiffness curve diagram, (c) is an energy consumption dynamic stiffness curve diagram, (d) is a hysteresis angle curve diagram, and (e) is an equivalent viscous damping curve diagram. DETAILED DESCRIPTION

[0057] In order to better understand the technical solution of the present invention, the embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0058] It should be clear that the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0059] In view of the shortcomings of the prior art, the present invention provides a method and idea for auxiliary development of a powertrain suspension system, and its flow chart is as follows: Figure 1 The following is a description of the contents of each major step.

[0060] 1. Data input:

[0061] The data input of the present invention adopts the template import method, that is, the parameters are filled into the template, and the template is imported into the auxiliary development system for processing and analysis. Compared with the traditional input method, this method is convenient for a set of parameters to be used multiple times, which meets the needs of repeated testing, repeated analysis, repeated optimization and adjustment in the process of powertrain suspension development, saves the time of repeated parameter input, and is more convenient for management.

[0062] 2. Coordinate transformation:

[0063] Considering that the OEM usually cooperates with multiple units when developing the suspension system, due to different operating habits and reference standards, many important parameters follow different standards when measuring (or selecting), and these parameters need to be converted quickly and accurately. Parameter conversion can be divided into the following six types:

[0064] The first one is that the reference coordinate systems of the existing inertia parameters and the required inertia parameters are different, and the inertia parameters in the existing coordinate system are converted into the inertia parameters in the required coordinate system;

[0065] The second type is that the reference coordinate system directions of the existing inertia parameters and the required inertia parameters are the same, but their origins are different. The inertia parameters at the origin of the existing coordinate system are converted to the inertia parameters at the origin of the required coordinate system.

[0066] The third type is that a system is composed of multiple subsystems. The center of mass position and inertia parameters of two subsystems are known, and the center of mass position and inertia parameters of the synthesized system are calculated;

[0067] The fourth type is that a system consists of multiple subsystems. The center of mass position and inertia parameters of the entire system and one subsystem are known, and the center of mass position and inertia parameters of the remaining subsystem are calculated;

[0068] The fifth type is that the reference coordinate systems of the existing suspension position coordinates and the required suspension position coordinates are different, and the coordinate values ​​in different coordinate systems are converted;

[0069] Sixth, if all existing parameters are based on the vehicle coordinate system, all parameters can be converted into parameters with the powertrain center of mass coordinate system as the reference coordinate system.

[0070] The coordinate positions based on different coordinate systems can be converted through the coordinate conversion matrix. The following example is the coordinate conversion matrix of the position parameters between the first coordinate system and the second coordinate system (the parameters in the first coordinate system are converted to the parameters in the second coordinate system. The first and second coordinate systems have no special meaning and are just two randomly selected coordinate systems):

[0071]

[0072] where cos(α 1x ),cos(α 1y ),cos(α 1z ) respectively represent the angles between the x-axis of the second coordinate system and the x, y, and z-axis of the first coordinate system. The angles of the other axes of the second coordinate system are similar. That is, cos(β 1x ),cos(β 1y ),cos(β 1z ) respectively represent the angles between the y-axis of the second coordinate system and the x-, y-, and z-axes of the first coordinate system, cos(γ 1x ),cos(γ 1y ),cos(γ 1z ) represent the angles between the z-axis of the second coordinate system and the x-, y-, and z-axes of the first coordinate system. The position parameters in the second coordinate system can be calculated by the following formula:

[0073] X 2 =A 12 X 1 , where X 1 Represents the first coordinate system, X 2 Represents the second coordinate system.

[0074] In addition to the coordinate transformation matrix, the inertia parameter conversion based on different coordinate systems also requires the inertia tensor matrix. The following formula represents the inertia tensor matrix based on the first coordinate system:

[0075]

[0076] In the formula, x, y, and z refer to the x, y, and z directions of the first coordinate system, and J xx1 , J yy1 , J zz1 Respectively represent the moment of inertia in the x, y, and z directions, J xy1 , J yx1 , J yz1 , J zy1 , J xz1 , J zx1 Represents the product of inertia in each direction.

[0077] The powertrain inertia parameters based on the second coordinate system can be obtained by the following formula:

[0078] J 2 =A 12 'J 1 A 12

[0079] Among them, A 12 ' is A 12 The transpose of .

[0080] 3. Decoupling arrangement:

[0081] After determining the parameters in the standard coordinate system, the geometric parameters of the suspension system are checked through decoupling arrangement verification. Decoupling arrangement verification includes collision center verification and V-shaped suspension verification. The former can verify whether the front and rear suspensions meet the collision center of each other under the parameters of the current suspension system, and the latter can verify whether the V-shaped suspension arrangement rule is met under the parameters of the current suspension system. If not, the parameters can be adjusted according to the calculation results.

[0082] 4. Optimization:

[0083] When the designer has specific requirements for certain aspects of the performance of the suspension system (such as requirements for the natural frequency of each degree of freedom of the powertrain), the stiffness and installation angle of the suspension system can be optimized (or only the stiffness can be optimized) to obtain the suspension system parameters that meet the performance requirements, including deterministic optimization and robust optimization. The optimization process uses the genetic algorithm (GA algorithm) in MATLAB. By setting the objective function, setting the upper and lower limits after optimization, and limiting the number of optimizations, the stiffness and installation angle of the suspension system are optimized. The goal of deterministic optimization is to make the natural frequency and decoupling rate of the optimized system within the required range. The goal of robust optimization is not only to make the natural frequency and decoupling rate of the optimized system within the required range, but also to make the robustness of the optimized system within the required range. The robustness calculation method is to randomly generate a set of stiffness values ​​that meet the requirements in a statistical sense (simulating the errors in the stiffness of the suspension in real production, such as a 5% or 10% deviation), use these multiple sets of stiffness values ​​for dynamic analysis, and evaluate the robustness based on the proportion of results that meet the performance requirements.

[0084] 5. Dynamic analysis:

[0085] In order to reduce the error when analyzing with a 6-DOF model of a grounded suspension system, the present invention introduces a 13-DOF vehicle model. The 13 degrees of freedom include 6 degrees of freedom of the powertrain (6 degrees of freedom in space), 3 degrees of freedom of the vehicle body (vertical, roll, pitch) and 4 vertical degrees of freedom of the wheels. Accordingly, a vehicle coordinate system is introduced, with the origin located at the center of the front axle or other custom positions, the x-axis points to the rear of the vehicle, the y-axis points to the right of the vehicle, and the z-axis points to the top of the vehicle, so as to facilitate analysis and calculation based on the 13-DOF model, such as Figure 2 shown.

[0086] When performing dynamic analysis on the powertrain suspension system, you can use a 6-DOF model of the suspension system grounded for a simple dynamic analysis, or you can use a 13-DOF vehicle model to perform a more accurate dynamic analysis when more parameters are obtained. Dynamic analysis is an important step in evaluating suspension performance, and mainly includes modal analysis, harmonic response analysis, and transient response analysis.

[0087] The modal analysis module can calculate the natural frequency, decoupling rate and other information in each direction of the 6-DOF model / 13-DOF model. It should be pointed out that the output content of this module includes both the calculation results under the standard coordinate system and the calculation results before the coordinate system conversion, which are distinguished by text labels in the output content. According to the suspension system parameters, the vibration differential equations of the powertrain can be listed (depending on the model used, such as the 6-DOF model with the suspension system grounded, 6 differential equations are listed, and if the 13-DOF model of the whole vehicle is used, 13 differential equations are listed), and the coefficients of the vibration equations are written in matrix form:

[0088]

[0089] Among them, M is the mass matrix, K is the stiffness matrix, is the generalized acceleration vector, and q is the generalized displacement vector.

[0090] M 1 The eigenvalue of the matrix K is the natural circular frequency of the powertrain system, which is divided by 2π to obtain the natural frequency, and the corresponding eigenvector is the natural vibration mode.

[0091] When the vibration frequency is a certain order natural frequency, the system resonates, but the intensity of vibration in each degree of freedom is different. The decoupling rate is needed to represent the intensity of vibration in each direction. Here we use the vibration decoupling evaluation method based on the internal force of the system to calculate the decoupling rate in each direction.

[0092] The natural circular frequency of the system is ω i , the corresponding vibration mode is When the system undergoes the i-th order modal vibration, its generalized displacement can be expressed as:

[0093]

[0094] The generalized inertial force vector is:

[0095]

[0096] The maximum value of the total work done by the generalized inertial force on the generalized displacement is:

[0097]

[0098] Where m kl It represents the kth row and lth column element in the mass matrix, and the row corresponds to the degree of freedom;

[0099] The work done by the generalized inertial force on the degree of freedom k is:

[0100]

[0101] Under the i-th order modal vibration, the decoupling rate of degree of freedom k is:

[0102]

[0103] The decoupling rate is thus calculated.

[0104] In the prior art, the 13-DOF model is rarely used in dynamic analysis. The reason is that the calculation process of the 13-DOF model is very complicated, the theoretical data is very lacking and not standardized, and the results obtained by occasional analysis are often only individual aspects (such as natural frequency, stiffness matrix, etc.); the present application systematically studies the method of using the 13-DOF model for dynamic analysis, and implements it with the help of a computer. It not only standardizes the reference coordinate system of each parameter required for the 13-DOF dynamic analysis, but also can obtain the value that meets the requirements through coordinate transformation for the parameters that do not directly meet the requirements, so that the analyst can focus on the analysis itself; it also classifies and organizes many analysis results, and displays the results such as mass matrix, stiffness matrix, natural frequency and corresponding direction, main vibration mode and corresponding direction, decoupling rate and corresponding direction, vibration curve, etc., which is convenient for users to read and copy; it can also write the measured vibration signal into Excel during the 13-DOF transient analysis (a type of dynamic analysis), and use it as an excitation signal for transient analysis, which meets the actual needs of the project.

[0105] Harmonic response analysis can obtain the frequency response characteristics of each degree of freedom of the powertrain system. In essence, it generates sinusoidal wave excitation signals of different frequencies to simulate the effect of the unbalanced reciprocating inertia force of the engine on the powertrain. The vibration amplitude of the powertrain is different under the excitation of different frequencies. The frequency of the excitation at this time is used as the horizontal axis variable, and the ratio of the amplitude in different directions to the amplitude of the input excitation is used as the vertical axis variable. The vibration frequency response curve can be drawn to reflect the sensitive range of the powertrain suspension system to the excitation frequency.

[0106] For transient analysis, it is necessary to set the initial conditions of the system movement, including the initial displacement and initial velocity in each degree of freedom direction. If there are other external excitation forces during the vibration of the system, they can also be set by importing the excitation force data (two columns, one column for time and one column for excitation value) into Excel for the solution program to call. The theoretical basis for transient analysis is also the multi-degree-of-freedom motion differential equations. It should be noted that here, unlike solving the natural frequency of the system, the influence of damping needs to be considered. The expression (i.e. the differential equation for the generalized displacement vector) is as follows:

[0107]

[0108] Where M, C, and K are the mass matrix, damping matrix, and stiffness matrix, respectively, which are obtained by writing the Lagrange equation; q, They are the generalized displacement vector, generalized velocity vector and generalized acceleration vector, respectively, and the elements represent the displacement, velocity and acceleration in the direction of each degree of freedom; the Q matrix is ​​the generalized excitation force vector, and the elements represent the external forces in the directions of each degree of freedom. For directions without external forces, the corresponding elements in Q can be taken as 0. For directions subject to external forces, the corresponding elements in the Q vector need to be written as time domain expressions or the time domain curves of the external forces can be imported through Excel.

[0109] The differential equations of motion are written in the form of state-space models, and the ode45 solver is used to solve the differential equations. The initial values ​​during the solution are the initial conditions of the system motion (initial displacement and initial velocity). The external excitation force is added to the Q matrix by reading the values ​​in Excel and interpolating them. When the initial conditions and external excitation are determined, the vibration of each degree of freedom of the system can be obtained. Since the equations have been written in the form of state-space equations during the solution, the results obtained by the ode45 solver include both the displacement and the velocity of motion in each direction. The velocity obtained is differentiated to obtain the acceleration values ​​in each direction. After determining the position of a point, it can be converted into the three-dimensional acceleration value of a point through geometric relationships. This step can be used to calculate the acceleration time domain curve at the seat rail to analyze the vibration of the seat.

[0110] According to the above differential equation about the generalized displacement vector, after all the coefficients in the equation are determined, the displacement curve, velocity curve and acceleration curve in each degree of freedom direction can be obtained by using the ode45 solver built into MATLAB (Note: the ode45 solver can directly output the calculation results), and then the three-dimensional acceleration curve of a certain point can be obtained by the following formula.

[0111]

[0112] In the formula, A x , A y , A z They represent the three-dimensional acceleration of the point to be determined, Δx, Δy, Δz represent the relative values ​​of the x, y, z coordinates of the point to be determined relative to the x, y, z coordinates of the vehicle body center of mass, A bz is the acceleration value in the z direction at the center of mass of the vehicle body, A bα is the acceleration value in the α direction at the center of mass of the vehicle body, A bβ The acceleration value in the β direction at the center of mass of the vehicle body.

[0113] 6. Static analysis:

[0114] In order to ensure that the powertrain and each suspension can maintain a certain displacement range (deformation range) and force range under different working conditions, static analysis is required. In addition to the standard general 28 working conditions, custom working conditions are added for static analysis. The adjustment of custom working conditions is achieved by changing the magnitude and direction of the force. The force conditions of 29 working conditions are stored in a 6*1*29 three-dimensional matrix, and the stiffness matrix under the static stiffness value is calculated. According to the generalized Hooke's law, the displacement of the system in each direction can be calculated. The expression is as follows:

[0115] F=KX

[0116] The physical quantities in the formula, such as powertrain force, suspension stiffness, powertrain displacement, etc., are all generalized physical quantities.

[0117] The mount stiffness that needs to be input during analysis can be input in three different ways: linear stiffness (i.e., the stiffness is a constant), five-segment linear fitting (by inputting the deformation and force at six points on the "force-deformation" graph, a stiffness curve is approximately constructed), and quintic polynomial fitting (inputting a quintic stiffness curve expression). These three input methods correspond to different stages of mount development and have their own uses. After selecting an input method and calculating, a series of information such as the displacement of the powertrain, the deformation and force of each mount can be obtained, which is convenient for designers to check the layout of the engine compartment and the design performance of the mount.

[0118] 7. Hydraulic mount analysis:

[0119] According to the known parameters of the hydraulic mount that are input, the important parameters of the hydraulic mount that cannot be measured, such as the volume stiffness, equivalent piston area, and local loss coefficient, are calculated; then, the dynamic characteristics of the hydraulic mount are calculated based on the calculated important parameters and a curve graph is drawn.

[0120] For inertial channel hydraulic mounts (first generation hydraulic mounts), inertial channel-decoupled membrane hydraulic mounts (second generation hydraulic mounts) and active mounts based on hydraulic mount design, all their internal parameters can be identified through a combination of experiments and theoretical deductions (part of the parameters are obtained through experiments and the rest are calculated), including parameters such as the upper liquid chamber volume stiffness, equivalent piston area, local loss coefficient, etc., which are difficult to measure directly but have a huge impact on the dynamic characteristics of the mount. After all parameters are determined, the dynamic characteristics can be calculated and the dynamic characteristic curve can be drawn.

[0121] The volume stiffness of the upper liquid chamber is calculated by the following formula:

[0122]

[0123] Among them, K u1 is the volume stiffness of the upper liquid chamber, ρ is the liquid density, l is the length of the suspension inertia channel, f p is the frequency value of the intersection point (i.e., fixed point) on the experimental curve, A f is the cross-sectional area of ​​the inertial channel.

[0124] The equivalent piston area is calculated by the following formula:

[0125]

[0126] Among them, A p1 is the equivalent piston area, K inf is the high frequency energy storage dynamic stiffness, K r K is the energy storage dynamic stiffness of the rubber main spring, u1 is the volume stiffness of the upper liquid chamber.

[0127] The local loss coefficient is calculated by the following formula:

[0128] S d =S d1 +S d2 +S d3

[0129] Among them, S d is the total local loss coefficient, S d1 is the local shrinkage coefficient, S d2 is the local expansion coefficient, S d3 is the pipe bend loss coefficient.

[0130]

[0131] Among them, C v is the contraction coefficient, C c is the velocity coefficient, A f is the cross-sectional area of ​​the inertial channel, A 1 is the cross-sectional area of ​​the top of the lower liquid chamber, d i is the hydraulic diameter, R is the radius of curvature of the axis of the bend, and θ is the angle of change of the bend’s direction.

[0132] 8. Data exchange:

[0133] Data exchange includes analysis report output and database storage and retrieval.

[0134] Analysis report output: After each analysis calculation is completed, use MATLAB to generate the analysis results in the text document txt format, use the docx library in python to generate the analysis results into a word document in docx format, and use the pptx library in python to generate the analysis results into a ppt presentation in pptx format.

[0135] Database storage and acquisition: Calling the os, shutil, xlutils and other libraries in Python can save the generated files in the specified location of the computer disk. The analysis data includes but is not limited to vehicle information, suspension information, experimental data, and curve charts.

[0136] Importing data from a template for analysis is suitable for situations where only one computer is used for analysis. If multiple groups of developers use multiple computers for analysis at the same time, they can log in to the database and use the parameters in the database for analysis (the contents of the database are stored in the computer that serves as the server, and "online operations" can be performed on other computers to obtain the contents stored in the database).

[0137] Embodiment 1:

[0138] The development process of the suspension system is very complicated. If you rely solely on experience-based design and determine the installation position, angle and stiffness of the suspension based on experience, you often need to repeat the design and verification process many times, which is time-consuming and laborious. If you directly use multi-body dynamics simulation software to simulate and analyze the powertrain suspension system, there will be too much data to collect and prepare in the early stage, and it is more complicated to change the parameters, which is not fast and convenient. Therefore, based on the relevant theoretical knowledge of the powertrain suspension system and with the help of the powerful computing power of the computer, many important characteristics of the powertrain suspension system can be easily and quickly calculated.

[0139] Obtaining a set of parameters of the powertrain suspension system can be parameters in a standard coordinate system, that is, parameters in a powertrain mass center coordinate system. Since the 6-DOF model of suspension grounding is often used to analyze the suspension system in the past, the use of parameters based on the powertrain mass center coordinate system does not need to consider the layout of the powertrain, which is more convenient. However, the present invention introduces a more accurate 13-DOF model that can obtain more information through analysis. Since relevant information between the powertrain and the vehicle body (such as relative position) is required, the layout of the powertrain must be considered at this time. In order to facilitate the output of the analysis results, the whole vehicle coordinate system is introduced, and the corresponding output will also be performed in the whole vehicle coordinate system (when performing partial analysis, such as modal analysis, the analysis results in the powertrain mass center coordinate system will also be output for convenience). The parameters in the two coordinate systems can be converted through geometric relationships and mechanical relationships (coordinate transformation matrix, axis shift formula, moment of inertia synthesis / decomposition formula), and only one can be input.

[0140] A suspension often goes through multiple procedures during the development process, which requires cooperation between different departments or even different companies. Different units and individuals often have different habits or reference standards when designing and testing, resulting in different definitions of different types of parameters (mainly different reference coordinate systems). Parameter conversion can be achieved through mathematical methods such as coordinate transformation matrix, axis shift formula, moment of inertia synthesis / decomposition formula, etc.

[0141] Since not all analyses require the use of a 13-DOF vehicle model, the parameters involved in the powertrain suspension system (i.e., the parameters required for the 6-DOF model) are still based on the powertrain center of mass coordinate system (standard coordinate system) during analysis, including the mass and inertia parameters of the powertrain, the installation position and angle of the suspension, and the three-way main axis stiffness, etc., while the corresponding parameters of the body, suspension, and wheels (i.e., the parameters added by the 13-DOF model compared to the 6-DOF model) are based on the vehicle coordinate system. If all the parameters in the hands of the developer are based on the vehicle coordinate system, the parameters of the powertrain suspension system need to be converted to those based on the powertrain center of mass coordinate system (standard coordinate system). The following is a set of all parameters based on the vehicle coordinate system.

[0142] The parameters of the powertrain, body, and wheels are shown in the three sub-tables in Table 1 respectively.

[0143] Table 1

[0144]

[0145] The parameters of the three suspensions are shown in the three sub-tables of Table 2 below.

[0146] Table 2

[0147]

[0148] The parameters of the suspension and tires are shown in the two sub-tables of Table 3.

[0149] Table 3

[0150]

[0151] The above parameters are converted into parameters based on the powertrain mass center coordinate system. The results after conversion are as follows:

[0152] The parameters of the powertrain, body, and wheels after conversion are shown in the three sub-tables of Table 4.

[0153] Table 4

[0154]

[0155] The parameters of the three suspensions after conversion are shown in the three sub-tables of Table 5.

[0156] Table 5

[0157]

[0158] The parameters of the suspension and tire after conversion are shown in the two sub-tables of Table 6.

[0159] Table 6

[0160]

[0161] The converted parameters are used in the subsequent calculations of the examples below.

[0162] When inputting suspension system information, special attention should be paid to the input of suspension inclination angle. In the past, the "rotation angle" method was often used for input, that is, the suspension was rotated around a certain coordinate axis by an angle. Although this method is simple, it is not applicable when the suspension installation inclination angle is more complicated. Therefore, we introduced two more comprehensive input methods. The similarities are that the three main stiffness axes of the suspension, u, v, and w axes, must be defined by the user before use. Try to make the main stiffness direction that is in the same direction as the x-axis of the reference coordinate system (powertrain center of mass coordinate system / vehicle coordinate system, depending on which coordinate system the other parameters refer to) be the u-axis. The following example is based on the powertrain center of mass coordinate system (standard coordinate system). If input is based on the vehicle coordinate system, simply replace the x, y, and z axes of the powertrain center of mass coordinate system with the x, y, and z axes of the vehicle coordinate system.

[0163] The first method is the Euler angle input method. When the u, v, and w axes are in the same direction as the x, y, and z axes respectively, the Euler angle input is (0,0,0). When the u axis is in the same direction as the x axis of the powertrain center of mass coordinate system and the three-way principal stiffness axis coordinate system of the suspension is only rotated around the u axis by an angle sita, the input Euler angle is (0,sita,0). The Euler angle input method can meet the needs of most cases. The second method is the coordinate axis angle input method, that is, the angles between the u, v, and w axes and the x, y, and z axes of the powertrain center of mass coordinate system are input respectively, that is, 9 angle values ​​need to be input for a suspension main stiffness axis coordinate system. This input method is only used when the angular relationship between the suspension coordinate system and the powertrain center of mass coordinate system is very complex, and can only be used for dynamic analysis and static analysis. It is not applicable to decoupling arrangement verification and system optimization.

[0164] The powertrain coordinate system (including the powertrain center of mass coordinate system and the powertrain vehicle coordinate system, collectively referred to as the powertrain coordinate system here) is the x, y, and z axes, and the suspension coordinate system is the u, v, and w axes, which respectively represent the three main stiffness directions of the suspension. The original suspension inclination input method can only represent the two-dimensional angular relationship between the suspension coordinate system and the powertrain coordinate system, that is, the u, v, and w axes of the suspension coordinate system correspond to the x, y, and z axes of the powertrain coordinate system at the initial moment, and the suspension coordinate system only rotates an angle around the u axis at subsequent moments. The new input method can represent the three-dimensional angular relationship between the suspension coordinate system and the powertrain coordinate system. The Euler angle input method describes this angular relationship from the perspective of "process", that is, the u, v, w axes of the mount coordinate system correspond to the x, y, z axes of the powertrain coordinate system at the initial moment. The first rotation is to rotate the entire mount coordinate system around the w axis, the second rotation is to rotate the entire mount coordinate system around the u axis, and the third rotation is to rotate the entire mount coordinate system around the w axis again. The input content is the angle of these three rotations (named precession angle, nutation angle, and rotation angle respectively); the coordinate axis angle input method describes this angular relationship from the perspective of "result", and the angle values ​​of u, v, w and the x axis, the angle values ​​of u, v, w and the y axis, and the angle values ​​of u, v, w and the z axis are input in sequence. Through the above two input methods, any angular relationship between the powertrain coordinate system and the mount coordinate system can be expressed.

[0165] By calculating the position parameters of the two suspensions in the front and rear of the suspension system, it can be determined whether the two suspensions are the collision center of each other. If they are two suspensions on the same side, or the same one is selected, there is no need to check the collision center at this time. By comparing the position coordinates of the suspensions, a judgment can be made in advance. After analysis and calculation, suspensions 1 and 2, and suspensions 1 and 3 do not meet the layout position requirements of the collision center (1 is the front suspension, 2 and 3 are both rear suspensions). If the collision center theory needs to be met, the parameters need to be adjusted.

[0166] The impact center determination includes:

[0167] First, determine whether the selected mounts are the same mount (based on the sequence number), and then determine whether the selected mounts are two mounts on the same side (based on whether the x-direction coordinates of the selected mounts have the same sign. If they have the same sign, they are mounts on the same side. If they have different signs, they are mounts on different sides). For mounts on different sides, determine whether they meet the impact center theory. The judgment formula is as follows:

[0168] J yy / m=L f ·L r

[0169] When this equation is satisfied, it is consistent with the impact center theory. yy is the moment of inertia of the powertrain in the y direction, m is the mass of the powertrain, L f is the absolute value of the x-coordinate of the front suspension, L r is the absolute value of the x-coordinate of the rear suspension.

[0170] The two suspension positions that meet the V-shaped suspension layout are symmetrical, with opposite inclination angles, and the intersection of one pair of main stiffness axes is exactly on the x-axis of the powertrain (the powertrain center of mass coordinate system). This layout can maximize the decoupling rate (reduce the coupling of vibrations in each degree of freedom direction) and facilitate vibration isolation design. After analysis and calculation, the current suspension layout does not meet the V-shaped suspension layout requirements. If the V-shaped suspension theory is to be met, the parameters need to be adjusted.

[0171] By drawing the torque axis and the suspension coordinate position together on the three-view drawing, their positional relationship can be intuitively seen. Under the current parameters, the three-view drawing of the torque axis is as follows: Figure 3 shown.

[0172] System optimization can be performed only for the stiffness value, or for the stiffness value and the installation inclination angle at the same time. The optimization principle is similar, and both use genetic algorithms for optimization. Different optimization methods follow different objective functions. When deterministic optimization is performed, the optimization goal is to make the natural frequency and decoupling rate in each direction meet the requirements as much as possible; the goal of robustness optimization is to make the natural frequency and decoupling rate in each direction meet the requirements, and the robustness also meets the user's requirements as much as possible. While optimizing, calculate the system robustness under the optimized parameters. The calculation method is to randomly generate a set of stiffness values ​​that meet the requirements in a statistical sense (simulating the errors in the suspension stiffness in real production, such as 5% or 10% deviation), use these multiple sets of stiffness values ​​for dynamic analysis, and evaluate the system robustness based on the proportion of results that meet the performance requirements. The initial stiffness value and angle value are the above-mentioned input parameters, and the optimized stiffness value and angle value are as follows.

[0173] Among them, the results of the three mounts after deterministic optimization are shown in the three sub-tables of Table 7.

[0174] Table 7

[0175]

[0176] The results of the three mounts after robustness optimization are shown in the three sub-tables of Table 8.

[0177] Table 8

[0178]

[0179] When performing dynamic analysis on the powertrain suspension system, you can use a 6-DOF model of the suspension system grounded for a simple dynamic analysis, or you can use a 13-DOF vehicle model to perform a more accurate dynamic analysis when more parameters are obtained. Dynamic analysis is an important step in evaluating suspension performance, and mainly includes modal analysis, harmonic response analysis, and transient response analysis.

[0180] Modal analysis. Based on the suspension system parameters, the vibration differential equations of the powertrain can be listed (depending on the model used, such as the 6-DOF model of the suspension system grounded, 6 differential equations are listed, and if the 13-DOF model of the whole vehicle is used, 13 differential equations are listed). Then, by obtaining the eigenvalues ​​and eigenvectors of the corresponding matrix, the following results can be obtained:

[0181] Using the 6-DOF model (based on the powertrain center of mass coordinate system):

[0182]

[0183] Using 6-DOF model (based on vehicle coordinate system):

[0184]

[0185] Using the 13-DOF model:

[0186]

[0187] Harmonic response analysis. The essence is to generate sinusoidal excitation signals of different frequencies to simulate the effect of the unbalanced reciprocating inertia force (or unbalanced overturning torque) of the engine on the powertrain. The vibration amplitude of the powertrain is different under the excitation of different frequencies. The harmonic response curve reflects the sensitive range of the powertrain suspension system to the excitation frequency. The calculation results are as follows:

[0188] The harmonic response curve of unbalanced reciprocating inertia force is as follows Figure 4As shown in the figure, we can get the frequency bands with more obvious vibrations in all directions, so we can avoid these frequency ranges when designing the suspension system.

[0189] The harmonic response curve for the unbalanced overturning torque is as follows: Figure 5 As shown in the figure, we can get the frequency bands with more obvious vibrations in all directions, so we can avoid these frequency ranges when designing the suspension system.

[0190] Transient analysis can obtain the vibration of the system in each degree of freedom under certain specific initial conditions or in the presence of external excitation, and can further calculate the three-dimensional acceleration values ​​of the check points specified by the developer. The following are the results of the analysis.

[0191] Using a 6-DOF model, where the initial conditions are not zero (initial displacement and initial velocity), the transient analysis results are as follows Figure 6 As shown, the time domain curves (free vibration) of the displacement of the powertrain in various directions can be seen from the figure.

[0192] Using a 13-DOF model, where the initial conditions are 0 (initial displacement and initial velocity) but an excitation force in the RY direction is added, the transient analysis results are as follows Figure 7 As shown, the time domain curves of displacement in each direction (forced vibration) can be seen from the figure.

[0193] The x, y, and z acceleration curves at the specified body measurement point are as follows: Figure 8 shown.

[0194] In addition to the 28 common working conditions in the industry, the static analysis also includes the 29th working condition - the custom working condition. The adjustment of the custom working condition is achieved by changing the magnitude and direction of the force. In the example here, the 29th working condition is set to a vertical downward force on the powertrain with a magnitude of 2132.7N.

[0195] There are three ways to input stiffness during calculation. The first is to input stiffness as a fixed value, which is the static stiffness value (linear stiffness) of the mount in the above parameters. The second is to select 6 points in the stiffness curve to approximate the nonlinearity of the mount stiffness (five-segment linear fitting stiffness). The third is to express the nonlinearity of the mount stiffness in the form of a fifth-order polynomial (fifth-order polynomial fitting stiffness). The force-displacement curves (stiffness curves) of the three directions of the u, v, and w axes of each mount are as follows: Fig. 9 shown.

[0196] The results of the static analysis are as follows, showing the absolute displacement of the powertrain under various operating conditions.

[0197] When linear stiffness:

[0198]

[0199]

[0200] When the five-segment linear fitting stiffness is:

[0201]

[0202] When fitting the stiffness with a fifth-order polynomial:

[0203]

[0204]

[0205] For inertial channel hydraulic mounts (first generation hydraulic mounts), inertial channel-decoupled membrane hydraulic mounts (second generation hydraulic mounts), and active mounts based on hydraulic mounts, all their internal parameters can be identified through a combination of experiments and theoretical deductions. The operator needs to prepare at least two hydraulic mounts with similar characteristics, disassemble one of the mounts, and directly measure parameters such as liquid density, inertial channel length, and inertial channel cross-sectional area; after draining the liquid of the hydraulic mount, perform passive characteristics in a liquid-free state, and obtain parameters such as rubber main spring energy storage dynamic stiffness and rubber main spring damping through experimental curves; use another intact mount to measure the passive characteristics (dynamic stiffness) of the liquid-filled state, and you can get the values ​​of the fixed point, peak value, and horizontal segment, and then calculate the remaining parameters to make a dynamic characteristic curve. Fig.10 The dynamic characteristic curve is an example.

[0206] The analysis results of each step of the above operation can be saved in txt / docx / pptx format. The following examples show txt and docx formats.

[0207] txt format:

[0208]

[0209] docx format:

[0210] ■1. Suspension system input information

[0211] ■1.1. Powertrain mass (unit: kg), inertia (unit: kg*m^2) and center of mass coordinates in the vehicle coordinate system (unit: mm)

[0212] m xpo ypo z 217.467 -222.965 -12.4953 182.3 Jxx Jyy Jzz Jxj J Jxj 7.994915 15.873192 13.85684 0.471089 0.271139 1.676056

[0213] ■1.2. Coordinates of the suspension elastic center in the vehicle coordinate system (unit: mm), Euler angle (unit: deg)

[0214] x y z Precession Angle Nutation angle Rotation angle Q1 546.7 -184.31 36.51 0.0 0.0 0.0 Q12 -367.2 -361.64 -7.36 0.0 0.0 0.0 Q3 -70.4 68.94 -274.09 0.0 0.0 0.0 Q4 2.8 -512.28 -424.48 0.0 0.0 0.0 Q5 0.0 0.0 0.0 0.0 0.0 0.0 Q6 0.0 0.0 0.0 0.0 0.0 0.0 Q7 0.0 0.0 0.0 0.0 0.0 0.0 Q8 0.0 0.0 0.0 0.0 0.0 0.0

[0215] ■1.3. Angle between the center of suspension elasticity and the vehicle coordinate system (unit: deg)

[0216] αu αv αw βu βv βw γu γv γ Q1 0.0 90.0 90.0 90.0 0.0 90.0 90.0 90.0 0.0 Q2 0.0 90.0 90.0 90.0 0.0 90.0 90.0 90.0 0.0 Q3 0.0 90.0 90.0 90.0 0.0 90.0 90.0 90.0 0.0 Q4 0.0 90.0 90.0 90.0 0.0 90.0 90.0 90.0 0.0 Q5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Q6 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Q7 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Q8 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

[0217] ■1.4. Static stiffness (unit: N / mm) and dynamic stiffness (unit: N / mm) of the suspension main axis

[0218] kus kvs kws kud kvd kwd Q1 100.0 100.0 100.0 98.58 155.34 184.52

[0219] The above is a detailed introduction to a method for assisting the development of a powertrain suspension system provided by an embodiment of the present application. The description of the above embodiment is only used to help understand the method and its core idea of ​​the present application; at the same time, for a person skilled in the art, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as limiting the present application.

Claims

1. A method for auxiliary development of a powertrain suspension system, It is characterized in that The method includes: Data input: obtaining known parameter data and importing it with a specific template for subsequent processing; the parameter data includes powertrain suspension system parameters and hydraulic suspension parameters; The analysis of the powertrain mounting system parameters includes: Coordinate conversion: determining whether the powertrain suspension system parameters belong to the coordinate parameters of the standard coordinate system, and if not, converting the coordinates into the coordinates of the standard coordinate system; Dynamic analysis: Dynamic analysis of the powertrain suspension system parameters in the standard coordinate system; dynamic analysis using a 6-degree-of-freedom model of the suspension system grounded and / or a 13-degree-of-freedom model of the vehicle; dynamic analysis includes modal analysis, harmonic response analysis and transient response analysis; the results of the dynamic analysis include: decoupling rates of each order mode and each direction, transient response data under different initial conditions and acceleration data of a certain point, and frequency response data in each direction; Wherein, the decoupling rate of the degree of freedom k under the i-th order modal vibration is calculated as follows: in, In the formula, m kl represents the element in the mass matrix, ω i is the i-th order natural circular frequency, and are the values ​​of k and l degrees of freedom in the i-th order modal vector corresponding to the i-th order natural circular frequency, respectively, c i is a multiple value, i is a positive integer; Static analysis: static analysis is performed on the parameters of the powertrain mounting system in the standard coordinate system; the results of the static analysis include: the analysis results of the traditional 28 working conditions of the powertrain mounting system under different stiffness input forms and the analysis results of the powertrain mounting system under custom working conditions; the custom working conditions are adjusted by changing the magnitude and direction of the force; The analysis of the hydraulic mount parameters includes: Hydraulic mount analysis: calculating unmeasurable parameters of the hydraulic mount according to the hydraulic mount parameters, and calculating dynamic characteristic data of the hydraulic mount according to the unmeasurable parameters and the hydraulic mount parameters.

2. The method for auxiliary development of a powertrain suspension system according to claim 1, It is characterized in that The method also includes, before the dynamic analysis: Adjustment and optimization: Determine whether the powertrain suspension system parameters in the standard coordinate system meet the decoupling layout standards and optimization standards. If not, make adjustments and optimizations.

3. The method for auxiliary development of a powertrain suspension system according to claim 1, It is characterized in that The unmeasurable parameters of the hydraulic mount include the upper liquid chamber volume stiffness, the equivalent piston area and the local loss coefficient.

4. The method for auxiliary development of a powertrain suspension system according to claim 1, It is characterized in that The standard coordinate system is the powertrain mass center coordinate system; The coordinate transformation matrix is ​​used to realize the conversion between coordinates in different coordinate systems.

5. The method for auxiliary development of a powertrain suspension system according to claim 2, It is characterized in that Adjustments and optimizations include: Deterministic optimization, so that the optimized system natural frequency and decoupling rate reach the required range; and robustness optimization, so that the robustness of the optimized system reaches the required range; The deterministic optimization and the robust optimization are both implemented using genetic algorithms, and the stiffness and installation angle of the suspension system are optimized by setting an objective function, setting upper and lower limits after optimization, and limiting the number of optimizations.

6. The method for auxiliary development of a powertrain suspension system according to claim 1, It is characterized in that The harmonic response analysis includes: applying excitation signals of different frequencies to the powertrain, taking the frequency of the excitation signal as the horizontal axis variable, taking the ratio of the amplitude of the powertrain in different directions to the amplitude of the excitation signal as the vertical axis variable, and drawing a vibration frequency response curve to reflect the sensitive range of the powertrain suspension system to the excitation frequency.

7. The method for auxiliary development of a powertrain suspension system according to claim 1, It is characterized in that The static analysis includes: storing the stress conditions of 29 working conditions in a 6*1*29 three-dimensional matrix, calculating the stiffness matrix under the static stiffness value, and calculating the displacement of the system in all directions according to the generalized Hooke's law; the expression is as follows: F=KX In the formula, F represents the force of the powertrain, K represents the suspension stiffness, and X represents the displacement of the powertrain, all of which are generalized physical quantities.

8. The method for auxiliary development of a powertrain suspension system according to claim 1, It is characterized in that The powertrain suspension system parameters include suspension inclination angle; The input method of the suspension inclination angle is the Euler angle input method or the coordinate axis angle input method; The specific method of inputting Euler angles is as follows: when the u, v, and w axes of the main stiffness axis coordinate system of the mount are in the same direction as the x, y, and z axes of the standard coordinate system, the input Euler angle is (0, 0, 0); when the u axis is in the same direction as the x axis of the powertrain center of mass coordinate system and the three-way main stiffness axis coordinate system of the mount is only rotated around the u axis by an angle sita, the input Euler angle is (0, sita, 0); The specific method of inputting the coordinate axis angle is: input the angles between the u, v, w axes of the main stiffness axis coordinate system of the suspension and the x, y, z axes of the standard coordinate system respectively; the data of this input method is used for dynamic analysis and static analysis.

9. A system for assisting the development of a powertrain suspension system. It is characterized in that The system comprises: Data input module: used to obtain known parameter data and import it with a specific template for subsequent processing; the parameter data includes powertrain suspension system parameters and hydraulic suspension parameters; Coordinate conversion module: used to determine whether the powertrain suspension system parameters belong to the coordinate parameters of the standard coordinate system, and if not, convert the coordinates into the coordinates of the standard coordinate system; Dynamic analysis module: used to dynamically analyze the parameters of the powertrain suspension system in the standard coordinate system; adopt the 6-degree-of-freedom model of the suspension system grounded and / or the 13-degree-of-freedom model of the whole vehicle for dynamic analysis; the dynamic analysis module includes a modal analysis module, a harmonic response analysis module and a transient response analysis module; the output results of the dynamic analysis module include: decoupling rates of each order mode and each direction, transient response data under different initial conditions and acceleration data of a certain point, and frequency response data in each direction; Wherein, the decoupling rate of the degree of freedom k under the i-th order modal vibration is calculated as follows: in, In the formula, m kl represents the element in the mass matrix, ω i is the i-th order natural circular frequency, and are the values ​​of k and l degrees of freedom in the i-th order modal vector corresponding to the i-th order natural circular frequency, respectively, c i is a multiple value, i is a positive integer; Static analysis module: used to perform static analysis on the parameters of the powertrain mounting system in the standard coordinate system; the output results of the static analysis module include: the analysis results of the traditional 28 working conditions of the powertrain mounting system under different stiffness input forms and the analysis results of the powertrain mounting system under the custom working conditions; the custom working conditions are adjusted by changing the magnitude and direction of the force; The hydraulic mount analysis module is used to calculate the unmeasurable parameters of the hydraulic mount according to the hydraulic mount parameters, and calculate the dynamic characteristic data of the hydraulic mount according to the unmeasurable parameters and the hydraulic mount parameters.

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