Evaluation method for vibration noise transmission path of electric drive system

Abstract

The invention relates to the field of new energy automobile electric driving systems, in particular to an evaluation method for a vibration noise transmission path of an electric driving system. According to the method, the vibration response of the suspension mounting point and the radiation of the electric drive system can be decomposed, and then the contribution degree of each excitation path to the vibration of the suspension mounting point and the contribution degree of each radiation surface to the sound pressure level of assembly sound radiation are obtained. Through the mode, comprehensive evaluation of the vibration noise transmission path of the electric drive system can be effectively realized, a basis is provided for research and development personnel, and the research and development personnel can carry out optimization design on the electric drive system through targeted analysis.

Description

Technical Field

[0001] The present invention relates to the field of electric drive systems for new energy vehicles, and in particular to a method for evaluating the vibration and noise transmission path of an electric drive system. Background Art

[0002] NVH (noise, vibration, and harshness) performance is a key indicator of vehicle comfort and quality. In traditional internal combustion engine vehicles, engine noise can mask other noise sources to a certain extent, thereby reducing the driver and passengers' perception of the vehicle's overall noise. However, for new energy vehicles, the electric drive system, as its core power source, generates vibration noise during operation that lacks the masking effect of engine noise, making it more easily perceived by the driver and passengers. As consumers' demand for vehicle quietness continues to increase, the NVH performance of electric drive systems has become a core factor affecting the competitiveness of new energy vehicles in the market, and vehicle manufacturers' requirements for NVH performance of electric drive systems are also increasing.

[0003] However, the electric drive system is a complex multi-physics coupling system, involving the interaction of multiple disciplines such as electromagnetics, mechanics, and acoustics. This multi-disciplinary coupling makes it difficult for traditional single-disciplinary analysis methods to fully reveal the transmission mechanism of vibration noise in the electric drive system. In addition, the excitation sources in the electric drive system exhibit diverse characteristics. For example, multiple excitations such as bearing forces, gear meshing forces, and motor electromagnetic forces are mutually coupled, making them difficult to separate and analyze individually. At the same time, the transmission path of vibration noise also exhibits nonlinear characteristics. For example, the vibration of the suspension mounting point is transmitted to the vehicle interior through the complex body structure, and the suspension components themselves have nonlinear characteristics, which further increases the difficulty of analyzing the vibration and noise transmission path of the electric drive system.

[0004] Therefore, in order to quickly and accurately resolve the problems of abnormal vibration, noise or acoustic harshness in specific areas or frequency bands within the vehicle caused by the transmission of electric drive vibration and noise during vehicle operation, there is an urgent need for an effective evaluation method for the vibration and noise transmission path of the electric drive system. This method can conduct in-depth analysis of the transmission path and enable R&D personnel to optimize the electric drive system through targeted analysis, thereby significantly improving the comfort of drivers and passengers. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies and provide a method for evaluating the vibration and noise transmission paths of electric drive systems. This method can decompose the vibration response of the suspension mounting point and the radiation of the electric drive system, thereby determining the contribution of each excitation path to the vibration of the suspension mounting point and the contribution of each radiating surface to the sound pressure level of the overall sound radiation. This method can effectively achieve a comprehensive evaluation of the vibration and noise transmission paths of the electric drive system, providing a basis for researchers to optimize the design of the electric drive system through targeted analysis.

[0006] The purpose of the present invention is to adopt the following scheme to achieve:

[0007] A method for evaluating the vibration noise transmission path of an electric drive system comprises the following steps:

[0008] 1) Construct a dynamic model based on the electric drive system;

[0009] 2) Using the dynamic model, construct a finite element model of the electric drive system;

[0010] 3) Based on the requirements of vibration transfer path analysis or noise control, multiple key areas are selected from all sound-radiating external surfaces of the electric drive system as surfaces of interest, and the surfaces of interest are divided into multiple analysis surfaces;

[0011] 4) According to the vibration transmission path analysis requirements or noise control requirements, determine the order of interest and the single bearing force order excitation force that needs to be loaded at the order frequency of interest;

[0012] 5) Loading the single bearing force order excitation force determined in step 4) into the finite element model, and calculating the nodal vibration velocity and equivalent acoustic power of each analysis surface to quantify the contribution of each surface of interest of the electric drive system to the assembly acoustic radiation;

[0013] 6) Decompose the suspension vibration propagation path, calculate the mean vibration acceleration of the suspension under a single bearing force order excitation force, and combine the node vibration velocity of each analysis surface and the equivalent acoustic power to form the acoustic vibration response calculation result of the electric drive system;

[0014] 7) Based on the acoustic and vibration response calculation results of the electric drive system, establish an acoustic radiation energy curve for acoustic radiation evaluation and a suspension vibration response hotspot map;

[0015] 8) Use the acoustic radiation energy curve to evaluate the acoustic radiation contribution of each concerned surface of the electric drive system. Based on the suspension vibration response hotspot map, evaluate the contribution of the excitation under each unidirectional transmission path to the vibration acceleration of the suspension mounting point.

[0016] Preferably, the dynamic model includes mechanical components and connection pairs of the electric drive system.

[0017] Preferably, in step 2), the specific method of constructing the finite element model of the electric drive system using the dynamic model is as follows:

[0018] 2-1) Extract key parameters of the kinetic model;

[0019] 2-2) Simplifying the dynamic model into an acoustic vibration calculation model based on the extracted key parameters of the dynamic model;

[0020] 2-3) Construct a finite element model based on the acoustic vibration calculation model.

[0021] Preferably, in step 4), the specific steps of determining the order of interest and the single bearing force order excitation force to be loaded at the order frequency of interest according to the vibration transfer path analysis requirements or noise control requirements are as follows:

[0022] 4-1) Input external excitation to obtain the time domain signal of the bearing force on the outer ring of each bearing of the electric drive system under steady-state conditions at different speeds;

[0023] 4-2) Decomposing and discrete Fourier transforming the acquired time domain signals of each bearing force to obtain a single bearing force frequency domain signal;

[0024] 4-3) Determine the order of interest based on vibration transfer path analysis requirements or noise control requirements;

[0025] 4-4) Determine the frequency of the order of interest based on the order of interest and the following formula:

[0026]

[0027] Where f is the frequency of the order of interest corresponding to the order of interest at the current speed; s is the speed in rpm; order is the order of interest;

[0028] 4-5) Based on the single bearing force frequency domain signal, extract the single bearing force frequency domain signal corresponding to the target order frequency, and obtain the single bearing force order excitation force that needs to be loaded.

[0029] Preferably, in step 4-2), the external excitation includes electromagnetic excitation and tooth surface surrounding parameter meshing excitation, and the input interval of the electromagnetic excitation is ≤0.2deg, and the input interval of the tooth surface surrounding parameter meshing excitation is ≤0.1deg.

[0030] Preferably, in step 5), the specific steps of loading the single bearing force order excitation force determined in step 4) to the finite element model and calculating the node vibration velocity and equivalent sound power of each analysis surface are as follows:

[0031] 5-1) Loading the single bearing force order excitation force determined in step 4) to the finite element model to obtain the vibration velocity of all nodes in each analysis surface;

[0032] 5-2) Based on the vibration velocities of all nodes within each analysis surface, the specific formula for obtaining the equivalent sound power of each analysis surface is as follows:

[0033]

[0034] Where P is the equivalent sound power; d is the gain coefficient; ρ is the air density under calculation conditions, in kg / m 2; c is the sound pressure wave velocity under calculation conditions, unit is m / s; A i is the equivalent area of ​​the ith node, in m 2 ;v i is the vibration velocity of the i-th node in the analysis plane, in m / s.

[0035] Preferably, in step 6), the calculation formula for the mean vibration acceleration of a certain suspension under a single bearing force order excitation force is as follows:

[0036]

[0037] Where a Fl is the mean vibration acceleration of K nodes; F k is the single bearing force order excitation force; K is the number of nodes; a nx is the vibration acceleration in the X direction of the mth node, a ny is the vibration acceleration in the Y direction of the mth node, a mz is the vibration acceleration in the Z direction of the mth node.

[0038] Preferably, in step 7), the specific method of establishing the sound radiation energy curve diagram and the suspension vibration response hotspot diagram based on the acoustic vibration response calculation results of the electric drive system is as follows:

[0039] 7-1) The specific steps for establishing the sound radiation energy curve are as follows:

[0040] 7-1-1) Based on the equivalent sound power and combined with the following formula, the equivalent amplitude of the sound pressure level is obtained:

[0041]

[0042] Where, P a is the equivalent amplitude of the sound pressure level; P is the equivalent sound power;

[0043] 7-1-2) A frequency threshold is provided for determining the method for correcting the equivalent amplitude of the sound pressure level. The A-weighted sound pressure level is used and the equivalent amplitude of the sound pressure level is corrected by the following method to obtain the corrected equivalent amplitude of the sound pressure level:

[0044] ① When the order frequency of interest is less than or equal to the frequency threshold, the following formula is used to perform an equivalent correction on the equivalent amplitude of the sound pressure level:

[0045]

[0046] Where, P a1 is the equivalent amplitude of the corrected sound pressure level; P a is the equivalent amplitude of the sound pressure level; P is the equivalent sound power;

[0047] ② When the order frequency of interest is greater than the frequency threshold, the following formula is used to perform an equivalent correction on the equivalent amplitude of the sound pressure level:

[0048] P a1 =P a -8

[0049] Where, P a1 is the equivalent amplitude of the corrected sound pressure level; P a is the equivalent amplitude of the sound pressure level;

[0050] 7-1-3) Create a sound radiation energy curve based on the order frequency of interest and the corrected sound pressure level equivalent amplitude;

[0051] 7-2) Based on the mean vibration acceleration and the excitation force path, establish a hotspot map of the suspension vibration response under each bearing excitation path at each order.

[0052] Preferably, in step 8), the sound radiation energy curve is used to obtain the corrected sound pressure level equivalent amplitude superposition and P of each order of interest surface. all , and according to the sound radiation energy curve, and the corrected sound pressure level equivalent amplitude superposition and P all , and evaluate the contribution of acoustic radiation of each concerned surface of the electric drive system.

[0053] Preferably, in step 8), based on the suspension vibration response hotspot map, the contribution of the excitation under each unidirectional transmission path to the vibration acceleration of the suspension mounting point is evaluated as follows:

[0054] ① Using the mount vibration response heat map and the following formula, the vivid acceleration level under each excitation path is obtained:

[0055]

[0056] Where D lf is the vibration acceleration level under the excitation force of the first single bearing force order; a Fl is the mean vibration acceleration of K nodes;

[0057] ② Superimpose the vibration acceleration levels under all excitation paths to obtain the vibration acceleration energy superposition and D of the suspension installation point under all path excitations. all ;

[0058] ③ According to the suspension vibration response hotspot map, as well as the superposition of the vibration acceleration energy of the suspension installation point under all path excitations and D all Evaluate the contribution of the suspension installation point to vibration acceleration.

[0059] The beneficial effects of the present invention are as follows:

[0060] A method for evaluating the vibration noise transmission path of an electric drive system comprises the following steps:

[0061] 1) Construct a dynamic model based on the electric drive system;

[0062] 2) Using the dynamic model, construct a finite element model of the electric drive system;

[0063] 3) Based on the requirements of vibration transfer path analysis or noise control, multiple key areas are selected from all sound-radiating external surfaces of the electric drive system as surfaces of interest, and the surfaces of interest are divided into multiple analysis surfaces;

[0064] 4) According to the vibration transmission path analysis requirements or noise control requirements, determine the order of interest and the single bearing force order excitation force that needs to be loaded at the order frequency of interest;

[0065] 5) Loading the single bearing force order excitation force determined in step 4) into the finite element model, and calculating the nodal vibration velocity and equivalent acoustic power of each analysis surface to quantify the contribution of each surface of interest of the electric drive system to the assembly acoustic radiation;

[0066] 6) Decompose the suspension vibration propagation path, calculate the mean vibration acceleration of the suspension under a single bearing force order excitation force, and combine the node vibration velocity of each analysis surface and the equivalent acoustic power to form the acoustic vibration response calculation result of the electric drive system;

[0067] 7) Based on the acoustic and vibration response calculation results of the electric drive system, establish an acoustic radiation energy curve for acoustic radiation evaluation and a suspension vibration response hotspot map;

[0068] 8) Use the acoustic radiation energy curve to evaluate the acoustic radiation contribution of each concerned surface of the electric drive system. Based on the suspension vibration response hotspot map, evaluate the contribution of the excitation under each unidirectional transmission path to the vibration acceleration of the suspension mounting point.

[0069] By constructing dynamic and finite element models, this method overcomes the limitations of traditional simplified models and enables precise analysis under complex conditions involving coupled excitation in multiple physical fields. This approach also enables refined analysis of vibration transmission paths and quantitative assessment of contributions to acoustic radiation, providing data support for optimizing the NVH performance of electric drive systems.

[0070] The present invention uses order frequency mapping and heat map visualization technology to accurately obtain the contribution of each excitation path to the vibration of the suspension installation point, as well as the contribution ratio of each radiating surface to the sound pressure level of the assembly sound radiation, to achieve a comprehensive evaluation of the vibration and noise transmission path of the electric drive system, and then quickly locate the key noise sources, enabling R&D personnel to optimize the design of the electric drive system through targeted analysis.

[0071] Preferably, in step 2), the specific method of constructing the finite element model of the electric drive system using the dynamic model is as follows:

[0072] 2-1) Extract key parameters of the kinetic model;

[0073] 2-2) Simplifying the dynamic model into an acoustic vibration calculation model based on the extracted key parameters of the dynamic model;

[0074] 2-3) Construct a finite element model based on the acoustic vibration calculation model.

[0075] This invention extracts the key parameters required for vibroacoustic analysis and simplifies them into a model suitable for vibroacoustic calculations. This model is then used to construct a finite element model. This effectively reduces the complexity of the model calculations while highly reproducing and fully preserving the dynamic characteristics of the dominant vibration path. This unique modeling approach successfully decouples vibration transmission paths from acoustic radiation, significantly improving computational efficiency and providing a highly efficient and reliable analysis tool for further research.

[0076] Preferably, in step 4), the specific steps of determining the order of interest and the single bearing force order excitation force to be loaded at the order frequency of interest according to the vibration transfer path analysis requirements or noise control requirements are as follows:

[0077] 4-1) Input external excitation to obtain the time domain signal of the bearing force on the outer ring of each bearing of the electric drive system under steady-state conditions at different speeds;

[0078] 4-2) Decomposing and discrete Fourier transforming the acquired time domain signals of each bearing force to obtain a single bearing force frequency domain signal;

[0079] 4-3) Determine the order of interest based on vibration transfer path analysis requirements or noise control requirements;

[0080] 4-4) Determine the frequency of the order of interest based on the order of interest and the following formula:

[0081]

[0082] Where f is the frequency of the order of interest corresponding to the order of interest at the current speed; s is the speed in rpm; order is the order of interest;

[0083] 4-5) Based on the single bearing force frequency domain signal, extract the single bearing force frequency domain signal corresponding to the target order frequency, and obtain the single bearing force order excitation force that needs to be loaded.

[0084] By acquiring the time-domain bearing force signals of each bearing outer ring at different steady-state speeds, decomposing and transforming them, this method can more clearly and intuitively present the excitation forces of different frequency components. Furthermore, by performing order analysis based on transmission path requirements or noise control needs, it is possible to accurately extract the single-order bearing force excitation force at the target order frequency of interest, thereby precisely locating the excitation source that has a critical impact on vibration and noise.

[0085] This method identifies the order of interest and the corresponding excitation force through specific analysis requirements, significantly enhancing the relevance of subsequent research on vibration and noise in electric drive systems. When conducting vibration transmission path analysis, the research focus can be placed on the transmission of specific order excitation forces within the system, clarifying the vibration propagation path and key links. In terms of noise control, the excitation force that generates the main noise can be optimized and improved, avoiding blind analysis and processing, significantly improving the accuracy and efficiency of analysis and control.

[0086] Preferably, in step 4-2), the external excitation includes electromagnetic excitation and tooth surface surrounding parameter meshing excitation, and the input interval of the electromagnetic excitation is ≤0.2deg, and the input interval of the tooth surface surrounding parameter meshing excitation is ≤0.1deg.

[0087] The present invention limits the input interval of external excitation, that is, by setting a smaller input interval, it can capture the excitation characteristics more accurately and avoid missing important excitation information due to excessively large intervals, so as to facilitate a more comprehensive analysis of the vibration and noise characteristics of the electric drive system under various working conditions and effectively improve the simulation accuracy.

[0088] Preferably, in step 5), the specific steps of loading the single bearing force order excitation force determined in step 4) to the finite element model and calculating the node vibration velocity and equivalent sound power of each analysis surface are as follows:

[0089] 5-1) Loading the single bearing force order excitation force determined in step 4) to the finite element model to obtain the vibration velocity of all nodes in each analysis surface;

[0090] 5-2) Based on the vibration velocities of all nodes within each analysis surface, the specific formula for obtaining the equivalent sound power of each analysis surface is as follows:

[0091]

[0092] Where P is the equivalent sound power; d is the gain coefficient; ρ is the air density under calculation conditions, in kg / m 2 ; c is the sound pressure wave velocity under calculation conditions, unit is m / s; A i is the equivalent area of ​​the ith node, in m 2 ;v iis the vibration velocity of the i-th node in the analysis plane, in m / s.

[0093] By applying a single bearing force order excitation force to the finite element model, this method can more accurately simulate the vibration state of the electric drive system under specific excitation. By analyzing the vibration velocity of the nodes on each analysis surface, the actual vibration conditions of each component can be effectively and accurately reflected, providing a detailed data foundation for subsequent analysis of the vibration response of each component and improving the accuracy of subsequent assessments of the sound radiation capacity of each analysis surface.

[0094] Preferably, in step 7), the specific method of establishing the sound radiation energy curve diagram and the suspension vibration response hotspot diagram based on the acoustic vibration response calculation results of the electric drive system is as follows:

[0095] 7-1) The specific steps for establishing the sound radiation energy curve are as follows:

[0096] 7-1-1) Based on the equivalent sound power and combined with the following formula, the equivalent amplitude of the sound pressure level is obtained:

[0097]

[0098] Where, P a is the equivalent amplitude of the sound pressure level; P is the equivalent sound power;

[0099] 7-1-2) A frequency threshold is provided for determining the method for correcting the equivalent amplitude of the sound pressure level. The A-weighted sound pressure level is used and the equivalent amplitude of the sound pressure level is corrected by the following method to obtain the corrected equivalent amplitude of the sound pressure level:

[0100] ① When the order frequency of interest is less than or equal to the frequency threshold, the following formula is used to perform an equivalent correction on the equivalent amplitude of the sound pressure level:

[0101]

[0102] Where, P a1 is the equivalent amplitude of the corrected sound pressure level; P a is the equivalent amplitude of the sound pressure level; P is the equivalent sound power;

[0103] ② When the order frequency of interest is greater than the frequency threshold, the following formula is used to perform an equivalent correction on the equivalent amplitude of the sound pressure level:

[0104] P a1 =P a -8

[0105] Where, P a1 is the equivalent amplitude of the corrected sound pressure level; P a is the equivalent amplitude of the sound pressure level;

[0106] 7-1-3) Create a sound radiation energy curve based on the order frequency of interest and the corrected sound pressure level equivalent amplitude;

[0107] 7-2) Based on the mean vibration acceleration and the excitation force path, establish a hotspot map of the suspension vibration response under each bearing excitation path at each order.

[0108] This invention accurately quantifies the acoustic radiation characteristics of electric drive systems by converting the physical quantity of sound power into a more intuitive sound pressure level that better reflects human auditory perception. Furthermore, by introducing a frequency threshold to correct the equivalent amplitude of the sound pressure level, the corrected equivalent amplitude can more accurately reflect the actual sound radiation, highly consistent with acoustic principles and practical engineering requirements.

[0109] Preferably, in step 8), the sound radiation energy curve is used to obtain the corrected sound pressure level equivalent amplitude superposition and P of each order of interest surface. all , and according to the sound radiation energy curve, and the corrected sound pressure level equivalent amplitude superposition and P all , and evaluate the contribution of acoustic radiation of each concerned surface of the electric drive system.

[0110] The present invention uses the sound radiation energy curve to visually see the radiation energy of each radiation surface at each frequency point under the order of interest. And by superposition of the corrected sound pressure level equivalent amplitude and P all Evaluating the acoustic radiation contribution of various areas of concern in the electric drive system can transform complex acoustic radiation problems into actionable mathematical criteria, enabling R&D personnel to quickly screen out high-contribution radiation surfaces, formulate targeted optimization strategies, and significantly improve the efficiency of NVH development.

[0111] Preferably, in step 8), based on the suspension vibration response hotspot map, the contribution of the excitation under each unidirectional transmission path to the vibration acceleration of the suspension mounting point is evaluated as follows:

[0112] ① Using the mount vibration response heat map and the following formula, the vivid acceleration level under each excitation path is obtained:

[0113]

[0114] Where D lf is the vibration acceleration level under the excitation force of the first single bearing force order; a Fl is the mean vibration acceleration of K nodes;

[0115] ② Superimpose the vibration acceleration levels under all excitation paths to obtain the vibration acceleration energy superposition and D of the suspension installation point under all path excitations. all ;

[0116] ③ According to the suspension vibration response hotspot map, as well as the superposition of the vibration acceleration energy of the suspension installation point under all path excitations and D all Evaluate the contribution of the suspension installation point to vibration acceleration.

[0117] The present invention can visually see the magnitude of each suspension vibration amplitude through the suspension vibration response hotspot map, and use the superposition of the vibration acceleration energy of the suspension installation point under all path excitations and D all To evaluate the contribution of vibration acceleration of the suspension installation point, it can achieve scientific quantification of the contribution of the vibration transmission path of the electric drive system, and transform the complex vibration transmission problem into an operational mathematical criterion, so that R&D personnel can quickly screen out high-contribution paths, formulate targeted optimization strategies, and significantly improve NVH development efficiency.

[0118] Glossary:

[0119] Joint: A joint element is an abstract unit used to describe the mechanical connection between two or more components in a mechanical system. It defines the relative motion and force transfer characteristics between components through constraints, stiffness characteristics, and excitation inputs. In the electric drive system dynamics model of this application, the joint element is a core element in constructing the system's dynamic response, directly affecting the transmission path and energy distribution of vibration noise.

[0120] Mounting points: These are the mechanical connections between the electric drive system (e.g., motor, reducer, controller, etc.) and the vehicle structure (e.g., frame, subframe). Mounts (typically rubber or hydraulic vibration isolation elements) are attached to these points with bolts and other fasteners, buffering the vibration and noise of the electric drive system from being transmitted to the vehicle body.

[0121] Finite Element Model: A finite element model (FEM) is a numerical analysis tool based on discretization. It decomposes a continuous physical structure into a finite number of units (such as tetrahedrons and hexahedrons) and establishes mechanical equilibrium equations at the unit nodes, thereby approximating mathematical models for solving complex engineering problems. In vibration and noise analysis of electric drive systems, finite element models are used to simulate structural vibration response and acoustic radiation characteristics, providing key data support for transmission path decomposition.

[0122] Surface of interest: A surface of interest refers to a specific external surface area in the electric drive system whose contribution to sound radiation needs to be analyzed.

[0123] Orders of Interest: "Orders of interest" refer to the specific vibration orders of interest when analyzing vibration and noise in electric drive systems. These orders are often directly related to key excitation sources within the system (such as gear meshing, electromagnetic forces, and rotating component imbalances). They are key parameters for locating noise sources and quantifying transmission paths.

[0124] Single bearing force order excitation force: refers to the excitation force extracted from the electric drive system dynamics model for a single bearing in a single direction (X / Y / Z) at a specific order frequency. It consists of three core elements, namely, single bearing force: the bearing force in a single direction of a single bearing (such as the X direction of the input shaft bearing); order excitation force: the excitation force corresponding to a specific vibration order (such as the gear meshing order, electromagnetic force order); frequency domain characteristics: containing amplitude and phase information for accurate analysis of the vibration transmission path. In this invention, the "single bearing force order excitation force" is used as the minimum unit for vibration noise analysis of the electric drive system. By independently quantifying the contribution of each bearing direction at a specific order, a refined decomposition of the transmission path is achieved.

[0125] Global Cartesian Coordinate System: A global Cartesian coordinate system is a unified, fixed coordinate system defined in a specific system or scene, used to uniquely determine the position and orientation of all objects. BRIEF DESCRIPTION OF THE DRAWINGS

[0126] Figure 1 This is the X-axis time domain force curve of the input shaft bearing of the end cover at a certain speed point in an embodiment of the present invention;

[0127] Figure 2 The X-axis frequency domain force amplitude and phase curve of the end cover input shaft bearing at a certain speed point in an embodiment of the present invention;

[0128] Figure 3 This is a graph showing the equivalent 1m sound pressure level of each panel in an embodiment of the present invention;

[0129] Figure 4 is a heat map of the suspension vibration response in an embodiment of the present invention;

[0130] Figure 5 Flowchart of the present invention. DETAILED DESCRIPTION

[0131] like Figures 1 to 5 As shown, a method for evaluating the vibration noise transmission path of an electric drive system is characterized by comprising the following steps:

[0132] 1) Construct a dynamic model based on the electric drive system;

[0133] The dynamic model includes the mechanical components and connections of the electric drive system. Mechanical components include surface-covered metal parts such as the housing, controller cover, resolver cover, and water jacket, as well as various closely mounted structures. It also includes the entire shaft system and the motor's stator and rotor components. Connections include bearing connections, gear connections, and motor connections.

[0134] In the process of building a dynamic model, its parameters need to be accurately set. For bearing connections, various design parameters need to be clarified, such as the bearing model, stiffness, damping and other key indicators; for gear connections, not only must its macro parameters, including module, number of teeth, tooth width, etc., be determined, but also micro parameters such as tooth profile error and tooth direction error need to be considered; and for motor connections, under specific analysis conditions, information such as stator radial force, tangential force and rotor torque fluctuation needs to be included. By accurately setting these parameters, it can be ensured that the model can truly and accurately reflect the dynamic characteristics of the electric drive system in actual operation.

[0135] 2) Using the dynamic model, the specific method of constructing the finite element model of the electric drive system is as follows:

[0136] 2-1) Extract key parameters of the kinetic model;

[0137] Based on the dynamic model constructed in step 1), accurately extract the stiffness (i.e., connection stiffness) and damping-related information for all joints. Specifically, for bearing joints, extract the radial stiffness, axial stiffness, and damping coefficient; for gear joints, obtain parameters such as tooth contact stiffness and meshing damping; and for motor joints, obtain data such as the stator-housing connection stiffness and electromagnetic damping.

[0138] 2-2) Based on the extracted key parameters of the dynamic model, the dynamic model is simplified into a vibroacoustic calculation model that retains the mass, stiffness, and damping characteristics of the electric drive system under motion conditions. This vibroacoustic calculation model provides a complete framework for vibration and noise analysis of the electric drive system, encompassing the coupled calculation of structural vibration and acoustic radiation.

[0139] 2-3) Based on the acoustic-vibration calculation model, a finite element model is constructed. This finite element model serves as the core tool for quantitative analysis of the vibration and noise of the electric drive system. Its key role is to convert the theoretical parameters of the dynamic model into quantifiable acoustic-vibration response data, thereby providing data support for subsequent contribution evaluation.

[0140] 3) Identify the sound radiating outer surfaces of the electric drive system, and select multiple key areas (i.e., determine the key sound radiation areas that need to be optimized) from all the sound radiating outer surfaces of the electric drive system as surfaces of interest based on the vibration transfer path analysis requirements or noise control requirements. The above-mentioned surfaces of interest are areas on the sound radiating outer surfaces of the electric drive system that have a greater impact on vibration and noise. In other words, the surfaces of interest are also key areas selected through vibration response analysis and modal evaluation. Their function is to focus on high-contribution sound radiation sources. By selecting surfaces of interest, the efficiency of NVH optimization of the electric drive system can be effectively improved.

[0141] Furthermore, each surface of interest is divided into multiple sub-regions according to structural features, and each sub-region is subjected to finite element meshing, that is, divided into q analysis surfaces.

[0142] 4) Based on the vibration transfer path analysis requirements or noise control requirements, determine the order of interest and the single bearing force order excitation force that needs to be loaded at the order frequency of interest. The specific steps are as follows:

[0143] 4-1) Input external excitation to obtain the time-domain signals of the bearing forces acting on the outer rings of each bearing in the electric drive system at different steady-state speeds. By obtaining these time-domain signals at different steady-state speeds, transient interference can be effectively eliminated, resulting in stable characteristic signals, providing a reliable data foundation for subsequent order analysis.

[0144] The external excitation includes electromagnetic excitation and tooth surface microscopic parameter meshing excitation, and in order to accurately reflect the characteristics of electromagnetic excitation and tooth surface microscopic parameter meshing excitation, there are requirements for the angular interval of the input and output results of the external excitation. Among them, electromagnetic excitation has high-frequency characteristics, and a smaller input interval can effectively avoid the signal aliasing phenomenon caused by insufficient sampling, thereby ensuring the integrity and accuracy of the time domain force signal. Therefore, making the input interval of electromagnetic excitation ≤0.2deg can effectively ensure that the waveform characteristics are fully captured in the dynamic changes of electromagnetic excitation such as motor stator radial force, tangential force and rotor torque fluctuations, and the output result point interval is ≤0.4deg.

[0145] During gear meshing, small changes in microscopic parameters can have significant effects at high frequencies (such as the meshing frequency and its multiples). A smaller input interval accurately reflects the transient characteristics of tooth contact and prevents mesh excitation distortion caused by sparse sampling. Therefore, the input interval for mesh excitation of tooth surface parameters is set to ≤0.1 degrees. Taking into account the input requirements of electromagnetic excitation and gear mesh excitation, the output result points are kept at a spacing of no more than 0.1 degrees, fully preserving the high-frequency details of the excitation signal.

[0146] In this embodiment, according to the input interval limit of the electromagnetic excitation and the tooth surface surrounding parameter meshing excitation, the output interval of the obtained bearing force time domain signal can be made no higher than 0.1deg (i.e. ≤0.1deg). In addition, when obtaining the bearing force time domain signal, it is necessary to ensure that the rotating component of interest rotates at least 2 circles (i.e. 720deg) under steady-state working conditions at different speeds to obtain at least 7200 time domain output results. For example, if the order of interest is the first-level gear meshing order, then at least the axis with the smaller rotation degree among the axes where the meshing gears are located (the axis system where the gear with more teeth among the two gears is located) is guaranteed to move more than two circles.

[0147] 4-2) Decompose the acquired bearing force time domain signals of each bearing outer ring using the global Carr coordinate system to obtain the bearing forces of each bearing connection pair outer ring in the X, Y, and Z directions, i.e., single bearing forces. In this embodiment, the electric drive system includes seven bearings. The acquired bearing forces acting on the seven bearing outer rings are decomposed into 21 single bearing forces in the X, Y, and Z directions in the global Carr coordinate system, which serve as 21 independent excitation forces.

[0148] The following formula is used to perform discrete Fourier transform on the above 21 single bearing forces (i.e., 21 independent excitation forces) to obtain single bearing force frequency domain signals. The single bearing force frequency domain signals retain the frequency domain amplitude and phase information of each single bearing force:

[0149]

[0150] Where, X k is the frequency domain value, X n is the time domain value, N is the number of sampling points, k is the frequency domain signal number, which is an integer in the range [0, N-1], π is the circumference of the circle, and j is the imaginary part.

[0151] It should be noted that, in order to ensure the accuracy of subsequent frequency domain calculations, when obtaining the bearing force time domain signal, the time domain signal length should ensure that the frequency resolution is not less than 1 Hz, and the sampling time interval should ensure that the maximum value of the analysis frequency is not less than twice the frequency corresponding to the highest speed point of the order of interest.

[0152] 4-3) Determine the order of interest based on vibration transfer path analysis requirements or noise control requirements;

[0153] 4-4) Determine the frequency of the order of interest based on the order of interest and the following formula:

[0154]

[0155] Where f is the frequency of the order of interest corresponding to the order of interest at the current speed; s is the speed in rpm; order is the order of interest;

[0156] In this embodiment, according to the vibration transfer path analysis requirement or the noise control requirement, the order of interest is determined to be 27, and the current rotation speed f is 6000 rpm. That is, the frequency of the order of interest can be determined to be 2700 Hz through the above formula.

[0157] 4-5) According to the single bearing force frequency domain signal, extract the corresponding single bearing force frequency domain signal at the target order frequency, including amplitude and phase results, and obtain one or more single bearing force order excitation forces F that need to be loaded. lTable 1 below shows the order frequency, amplitude, and phase results for the 27th-order gear meshing in the X-axis direction of the input shaft bearing in this embodiment. Since order calculation only requires analyzing the excitation frequency corresponding to the speed point, order force extraction can effectively reduce the computational time and resources required for order frequency-domain excitation calculations.

[0158] Table 1

[0159] Order frequency 224.957 337.4524 449.9497 562.4472 674.9452 787.4435 899.9418 Frequency amplitude 2.888101 2.846143 2.673496 2.445919 1.763144 4.705753 7.476035 Frequency Phase 32.00985 32.21195 34.66789 39.45796 87.70816 53.1324 86.62781 Order frequency 1012.441 1124.939 1237.438 1349.936 1462.437 1574.938 1687.441 Frequency amplitude 8.797719 8.083063 7.583779 5.961347 3.011993 2.769385 2.405538 Frequency Phase 39.63309 39.60989 10.79396 3.616539 -6.70556 29.18148 19.14723 Order frequency 1799.943 1912.447 2024.95 2137.454 2249.958 2362.46 2474.964 Frequency amplitude 1.848389 2.60101 4.097465 4.21694 3.419894 2.452516 2.264771 Frequency Phase 50.87938 75.21045 63.79266 44.82392 30.97076 30.77528 48.9997 Order frequency 2587.466 2699.969 2812.471 2924.975 3037.476 3149.977 3262.478 Frequency amplitude 2.429456 2.171467 2.57856 2.720729 2.786199 2.399653 2.075397 Frequency Phase 47.94492 52.96864 54.53438 49.07574 39.14812 27.84606 20.0174 Order frequency 3374.98 3487.483 3599.983 3712.486 3824.986 3937.487 4049.989 Frequency amplitude 1.706511 1.659965 1.542499 1.308828 1.103162 1.203268 1.533483 Frequency Phase 16.4345 12.46365 -6.11037 -27.3301 -39.996 -43.2853 -50.8181 Order frequency 4274.991 4499.994 4724.994 4949.996 5175 5400.003 5625.001 Frequency amplitude 1.732827 1.773974 1.506659 1.178899 1.432391 2.30828 3.673156 Frequency Phase -71.2311 -102.932 -136.116 -176.463 134.5173 76.60136 31.34775

[0160] 5) The single bearing force order excitation force F determined in step 4) is l Load the finite element model and calculate the nodal vibration velocity and equivalent sound power in each analysis surface to quantify the contribution of each surface of interest of the electric drive system to the assembly sound radiation.

[0161] 5-1) Apply one or more single-order bearing force excitations extracted in step 4) to the corresponding nodes in the finite element model (i.e., the finite element model nodes of each bearing outer ring roller contact surface). This ensures that the excitation force is consistent with the actual transmission path, thereby obtaining the vibration velocity of all nodes within each analysis surface. The node vibration velocity is actually the instantaneous velocity vector of each discrete node in the finite element model during vibration, including components in the X, Y, and Z directions. The vibration velocity of each node represents the local vibration characteristics of that location.

[0162] 5-2) Based on the vibration velocities of all nodes within each analysis surface, the equivalent sound power of each analysis surface is obtained to facilitate the evaluation of the contribution of different areas to sound radiation. The calculation formula for obtaining the equivalent sound power of each analysis surface is as follows:

[0163]

[0164] Where P is the equivalent sound power; d is the gain coefficient; ρ is the air density under calculation conditions, in kg / m 2 ; c is the sound pressure wave velocity under calculation conditions, unit is m / s; A i is the equivalent area of ​​the ith node, in m 2 ;v i is the vibration velocity of the i-th node in the analysis plane, in m / s.

[0165] 6) Decompose the suspension vibration propagation path, and obtain the vibration accelerations in the X, Y, and Z directions based on the node vibration velocities in the X, Y, and Z directions obtained in step 5-1), and use the following formula to calculate the excitation force F for each single bearing force order: l The following is the vibration result of a certain mount, that is, the average vibration acceleration of a certain mount:

[0166]

[0167] Where a Fl is the mean vibration acceleration of K nodes; F l is the single bearing force order excitation force; K is the number of nodes; a mx is the vibration acceleration in the X direction of the mth node, a my is the vibration acceleration in the Y direction of the mth node, a mz is the vibration acceleration in the Z direction of the mth node.

[0168] The mean vibration acceleration reflects mechanical vibration energy, not only assessing the vibration level at the mounting point but also providing a quantifiable technical indicator for vibration transmission path decomposition and contribution evaluation. Equivalent sound power, on the other hand, reflects acoustic radiation energy. By combining the nodal vibration velocities of each analysis surface with the equivalent sound power, the acoustic vibration response of the electric drive system is calculated, providing a dual-channel "mechanical vibration-acoustic radiation" evaluation system for the NVH performance of the electric drive system.

[0169] 7) Establish a sound radiation energy curve diagram and a suspension vibration response hotspot diagram.

[0170] 7-1) Based on the calculation results of the acoustic vibration response of the electric drive system, the specific steps for establishing the sound radiation energy curve for sound radiation evaluation are as follows:

[0171] 7-1-1) Based on the equivalent sound power and in combination with the following formula, the equivalent amplitude of the sound pressure level is obtained. In this embodiment, it is the equivalent near-field sound pressure level amplitude:

[0172]

[0173] Where, P a is the equivalent amplitude of the sound pressure level; P is the equivalent sound power;

[0174] 7-1-2) A frequency threshold is provided for determining the method for correcting the equivalent amplitude of the sound pressure level. In this embodiment, the frequency threshold is set to 2000 Hz based on a comprehensive consideration of acoustic propagation characteristics, human ear sensitivity, and engineering optimization strategies. Using the A-weighted sound pressure level, the equivalent amplitude of the sound pressure level (equivalent near-field sound pressure level amplitude) is corrected in the following manner to obtain the corrected equivalent amplitude of the sound pressure level:

[0175] ① When the order frequency of interest is ≤2000Hz, the equivalent amplitude of the sound pressure level is corrected using the following formula:

[0176]

[0177] Where, P a1 is the equivalent amplitude of the corrected sound pressure level; P a is the equivalent amplitude of the sound pressure level; P is the equivalent sound power;

[0178] ② When the order frequency of interest is greater than 2000 Hz, the equivalent amplitude of the sound pressure level is corrected using the following formula:

[0179] P a1 =P a -8

[0180] Where, P a1 is the equivalent amplitude of the corrected sound pressure level; P a is the equivalent amplitude of the sound pressure level;

[0181] In this embodiment, through equivalent correction, the corrected sound pressure level equivalent amplitude is the 1 m sound pressure level equivalent amplitude.

[0182] 7-1-3) According to the order frequency of interest and the corrected sound pressure level equivalent amplitude, establish the sound radiation energy curve, such as Figure 3 As shown, the horizontal axis is the frequency of the order of interest, and the vertical axis is the equivalent amplitude of the sound pressure level at 1 m;

[0183] 7-2) Based on the mean value of vibration acceleration and the excitation force path, establish the suspension vibration response hotspot map under each bearing excitation path at each order, such as Figure 4 As shown in the figure, the horizontal axis is the frequency of the order of interest, and the vertical axis is the excitation force path. Specifically, the excitation force path is the entire vibration propagation path from the excitation force application point to the response point of the suspension mounting point (i.e., the vibration propagation path from a single bearing force order excitation force to the response result of a certain suspension point).

[0184] 8) Using the sound radiation energy curve and the following formula, the corrected sound pressure level equivalent amplitude (1m sound pressure level equivalent amplitude) of each order of interest surface is obtained, and P all :

[0185]

[0186] Where, P all is the sum of the equivalent amplitudes of the sound pressure levels corrected on all analysis surfaces, P aq is the corrected sound pressure level equivalent amplitude of the qth analysis surface.

[0187] The evaluation of the vibration and noise transmission path of the electric drive system actually includes two aspects: the evaluation of the acoustic radiation contribution of each concerned surface of the electric drive system, and the evaluation of the contribution of the excitation to the vibration acceleration of the suspension installation point under each unidirectional transmission path. The specific evaluation method is as follows:

[0188] 8-1) According to the sound radiation energy curve, and the corrected sound pressure level equivalent amplitude superposition and P all , evaluate the contribution of acoustic radiation of each concerned surface of the electric drive system:

[0189] (1) The sound radiation energy curve is a visual tool for quantifying the contribution of each radiating surface of the electric drive system to the sound pressure level. Its role runs through the entire process of noise source location, contribution quantification and optimization strategy formulation.

[0190] like Figure 3 As shown, each curve corresponds to a radiating surface, and the peak position of each curve directly reflects the sound radiation intensity of the radiating surface at a specific frequency. Therefore, it is possible to intuitively see the amount of radiation energy radiated by each radiating surface at each frequency point under the order of interest. When it is necessary to reduce the sound radiation at a certain frequency, it can provide targeted guidance on which radiating surface should be optimized.

[0191] ⑵According to the modified sound pressure level equivalent amplitude superposition and P all The specific method for evaluating the acoustic radiation contribution of each concerned surface of the electric drive system is as follows:

[0192] ①If the condition P is met all -P aq >10*log 10 q, indicating that the sound pressure level of the qth surface is at least 10*log lower than the total sound pressure level 10 qdB, it is considered that under this operating condition, the contribution of the sound pressure level of the concerned surface to the total sound pressure level is very small, and the influence of the concerned surface on the sound radiation of the assembly at 1m can be ignored.

[0193] ②If condition P is not met all -P aq >10*log 10 q, it means that the sound pressure level of the concerned surface contributes to the total sound pressure level. Therefore, the influence of the concerned surface on the sound radiation of the assembly at 1m cannot be ignored, and the concerned surface may need to be optimized.

[0194] In this embodiment, as shown in Table 2, when the order frequency of interest is 1300 Hz, the corrected sound pressure level equivalent amplitude superposition and P all Approximately 78.782, passing the judgment condition 78.782-P aq >10*log 10 7. The corrected sound pressure level equivalent amplitude of each analysis surface is superimposed with the corrected sound pressure level equivalent amplitude and P all After judgment, the radiation surface of the right box, the radiation surface of the motor box, the radiation surface of the controller connection box, the radiation surface of the controller lower cover and the radiation surface of the resolver cover meet the requirements of 78.782-P aq >10*log 10 7, which means that the contribution of these surfaces to the sound radiation is very low and their influence on the 1m sound pressure level of the assembly can be ignored. aq With P allThe difference does not reach the threshold, and structural optimization needs to be carried out on this surface.

[0195] Frequency (Hz) Right box radiation surface Motor housing radiation surface Radiating surface of controller upper cover Controller connection box radiation surface Radiating surface of controller lower cover Large bracket radiation surface Radiation surface of the resolver cover Equivalent 1m sound pressure level 1200 57.15004877 60.90346177 63.62884277 65.80238777 58.06570077 65.60345377 53.95678877 70.92830051 1210 58.37580437 61.63933737 65.17439637 66.21025737 58.69110937 65.83525237 54.55948437 71.60629876 1220 59.5381727 62.4865267 66.8486977 66.7106087 59.4485287 66.1226927 55.2131177 72.43260882 1230 59.42913228 62.58207428 67.62114128 66.21450528 59.49854728 65.51133828 54.74267728 72.40562944 1240 59.3880525 62.8470475 68.6070465 65.7464435 59.7669865 64.9554735 54.3532505 72.59031245 1250 59.3459016 63.4196366 69.4413586 65.5965646 59.7903216 65.2153046 54.5541176 73.01897339 1260 59.39766573 64.10462973 70.33014073 65.48733673 59.90019073 65.54483473 54.78635773 73.54771563 1270 60.3457319 65.3867499 72.3869639 66.1916319 60.7406339 67.0695779 55.5500149 75.14068561 1280 61.330064 66.61077 74.152893 66.897039 61.570519 68.450242 56.303101 76.60061497 1290 62.26296881 67.19605281 75.60459481 67.02674881 61.53499581 69.42353981 56.79211481 77.70667268 1300 63.21674299 67.84211399 76.92782099 67.20368099 61.54178199 70.35951299 57.27905399 78.78237475 1310 63.06298311 67.08501811 76.21703411 67.51106111 61.11302611 69.99674911 57.03334811 78.22256815 1320 62.94028062 66.33368562 75.43951762 67.92817062 60.76830762 69.61704662 56.79734962 77.65605734 1330 62.54902086 65.38241386 74.66125686 68.92150986 61.98156086 68.85325986 55.92181386 77.15597101 1340 62.15192309 64.41811009 73.80019109 69.95134409 63.17580009 67.97658109 54.89149909 76.71605835 1350 62.11983945 64.09859845 72.91156345 70.11598445 63.96638745 67.42671645 53.99137545 76.26262594 1360 62.11964 63.837917 71.912709 70.339501 64.735274 66.83294 52.946985 75.84227238 1370 61.85413871 63.52353071 70.43126171 68.99943171 64.60706171 66.23971871 52.35301171 74.77660847 1380 61.59793645 63.21674345 68.72826845 67.46157045 64.48271445 65.59143045 51.70041945 73.64668053 1390 61.223418 62.842578 68.0183 65.689877 64.205761 64.991897 51.155488 72.83598808 1400 60.83445206 62.44570306 67.48921606 63.71211906 63.91359906 64.34235106 50.56337606 72.10116188

[0196] ization or damping to reduce its contribution to sound radiation.

[0197] Table 2

[0198] In summary, through the above judgment, the complex sound radiation problem can be transformed into an operational mathematical criterion, so that designers can aq Based on the sorting results, the system quickly identifies radiation surfaces with high contribution and formulates targeted strategies such as structural reinforcement, damping material addition, or surface stiffness optimization. This significantly improves the goal orientation and iterative efficiency of the NVH development process, and provides a scientific and efficient engineering solution for optimizing the acoustic and vibration characteristics of electric drive systems.

[0199] 8-2) Based on the mount vibration response hotspot map, evaluate the contribution of the excitation under each unidirectional transmission path to the vibration acceleration of the mount installation point:

[0200] (1) The suspension vibration response hotspot map is a visualization tool for quantifying the contribution of the vibration transmission path of the electric drive system. Its role runs through the entire process of vibration source location, path decomposition and optimization strategy formulation.

[0201] like Figure 4 As shown, the suspension vibration response hotspot map can intuitively show the magnitude of each suspension vibration amplitude. In this hotspot map, the brighter the area, the greater the suspension vibration acceleration level (suspension vibration amplitude), indicating that the vibration contribution of this path is greater and needs to be the focus of optimization. This hotspot map is constructed based on the independent loading test results of the bearing force in each direction of each bearing and can provide key information in two dimensions:

[0202] First, frequency domain distribution characteristics: Through the color gradient change of the horizontal axis (the order frequency of interest), the peak frequency range of the suspension vibration acceleration level can be clearly identified.

[0203] Second, the excitation path contribution: The brightness distribution of the vertical axis (excitation force path, such as the input shaft bearing's X-axis) reflects the vibration transmission efficiency of different bearing excitation paths at specific frequencies. By cross-analyzing the frequency and path brightness extremes, the bearing force excitation path that causes the maximum suspension vibration amplitude can be precisely located. This allows for point-by-point optimization of the excitation path, quickly and accurately identifying problematic paths and frequencies.

[0204] ⑵Use the suspension vibration response hotspot map to obtain the vibration acceleration energy superposition and D of the suspension installation point under all path excitations. all The specific method to evaluate the contribution of the vibration acceleration of the suspension installation point is as follows:

[0205] ① Using the mount vibration response heat map and the following formula, the vivid acceleration level under each excitation path is obtained:

[0206]

[0207] Where D lf is the vibration acceleration level under the excitation force of the first single bearing force order; a Fl is the mean vibration acceleration of K nodes;

[0208] ② Superimpose the vibration acceleration levels under all excitation paths to obtain the vibration acceleration energy superposition and D of the suspension installation point under all path excitations. all , where the vibration acceleration energy of the suspension mounting point under all path excitations is superimposed and D all The calculation formula is:

[0209]

[0210] Where D all D is the sum of the vibration acceleration energy of the suspension mounting point under all path excitations. lf It is the sum of vibration acceleration energy of the suspension mounting point under the unidirectional path excitation force of a single bearing.

[0211] According to the superposition of vibration acceleration energy of the suspension mounting point under all path excitations and D all , the contribution of the suspension installation point vibration acceleration is evaluated in the following way:

[0212] If condition D is met all -D lf >10*log 10 l, indicating that the acceleration level of the lth path is at least 10*log lower than the total acceleration level 10 ldB, it is considered that under this operating condition, the acceleration level of the lth path contributes very little to the vibration acceleration level of the suspension installation point, and the impact of this path on the vibration of the suspension installation point can be ignored.

[0213] If condition D is not met all -D lf >10*log 10 l, it means that under this operating condition, the acceleration level of the lth path contributes to the vibration acceleration level of the suspension installation point, and the impact of this path on the vibration of the suspension installation point cannot be ignored. It is judged that the suspension installation point may need further optimization.

[0214] In this embodiment, as shown in Table 3 below (vibration level and superposition sum of a certain suspension installation point under each path excitation at a certain frequency point), when the order frequency of interest is 900 Hz, the superposition sum of the vibration acceleration energy of the suspension installation point under all path excitations of the suspension installation point is D all The calculation is 156.440dB, which passes the judgment condition 156.440-D lf >10*log 10 12. Quantify the vibration contribution of each excitation path. Calculations have verified that the paths including the end cover side input shaft bearing X, end cover side input shaft bearing Y, motor side input shaft bearing X, motor side input shaft bearing Y, motor side input shaft bearing Z, end cover side intermediate shaft bearing X, end cover side intermediate shaft bearing Y, motor side intermediate shaft bearing X, motor side intermediate shaft bearing Y, and motor side intermediate shaft bearing Z all meet the requirements of 156.440-D. lf >10*log 10 12, indicating that the contribution of vibration acceleration energy of these paths is very low.

[0215]

[0216] Its vibration effect on the suspension mounting point can be ignored.

[0217] Table 3

[0218] In summary, through the above judgment, the contribution of the vibration transmission path of the electric drive system can be scientifically quantified, and the complex vibration transmission problem can be converted into an operational mathematical criterion, enabling R&D personnel to quickly screen out high-contribution paths and formulate targeted optimization strategies, thereby improving NVH development efficiency.

[0219] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications made to the present invention by those skilled in the art without departing from the spirit of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A method for evaluating the vibration noise transmission path of an electric drive system, characterized in that: The following steps are involved: 1) Construct a dynamic model based on the electric drive system; 2) Using the dynamic model, construct a finite element model of the electric drive system; 3) Based on the requirements of vibration transfer path analysis or noise control, multiple key areas are selected from all sound-radiating external surfaces of the electric drive system as surfaces of interest, and the surfaces of interest are divided into multiple analysis surfaces; 4) According to the vibration transmission path analysis requirements or noise control requirements, determine the order of interest and the single bearing force order excitation force that needs to be loaded at the order frequency of interest; 5) Loading the single bearing force order excitation force determined in step 4) into the finite element model, and calculating the nodal vibration velocity and equivalent acoustic power of each analysis surface to quantify the contribution of each surface of interest of the electric drive system to the assembly acoustic radiation; 6) Decompose the suspension vibration propagation path, calculate the mean vibration acceleration of the suspension under a single bearing force order excitation force, and combine the node vibration velocity of each analysis surface and the equivalent acoustic power to form the acoustic vibration response calculation result of the electric drive system; 7) Based on the acoustic and vibration response calculation results of the electric drive system, establish an acoustic radiation energy curve for acoustic radiation evaluation and a suspension vibration response hotspot map; 8) Use the acoustic radiation energy curve to evaluate the acoustic radiation contribution of each concerned surface of the electric drive system. Based on the suspension vibration response hotspot map, evaluate the contribution of the excitation under each unidirectional transmission path to the vibration acceleration of the suspension mounting point.

2. The method for evaluating the vibration noise transmission path of an electric drive system according to claim 1, characterized in that: The dynamic model includes the mechanical components and the connection pairs of the electric drive system.

3. The method for evaluating the vibration noise transmission path of an electric drive system according to claim 1, characterized in that: In step 2), the specific method of constructing the finite element model of the electric drive system using the dynamic model is as follows: 2-1) Extract key parameters of the kinetic model; 2-2) Simplifying the dynamic model into an acoustic vibration calculation model based on the extracted key parameters of the dynamic model; 2-3) Construct a finite element model based on the acoustic vibration calculation model.

4. The method for evaluating the vibration noise transmission path of an electric drive system according to claim 1, characterized in that: In step 4), the specific steps for determining the order of interest and the single bearing force order excitation force to be loaded at the order frequency of interest based on the vibration transfer path analysis requirements or noise control requirements are as follows: 4-1) Input external excitation to obtain the time domain signal of the bearing force on the outer ring of each bearing of the electric drive system under steady-state conditions at different speeds; 4-2) Decomposing and discrete Fourier transforming the acquired time domain signals of each bearing force to obtain a single bearing force frequency domain signal; 4-3) Determine the order of interest based on vibration transfer path analysis requirements or noise control requirements; 4-4) Determine the frequency of the order of interest based on the order of interest and the following formula: Where f is the frequency of the order of interest corresponding to the order of interest at the current speed; s is the speed in rpm; order is the order of interest; 4-5) Based on the single bearing force frequency domain signal, extract the single bearing force frequency domain signal corresponding to the target order frequency, and obtain the single bearing force order excitation force that needs to be loaded.

5. The method for evaluating the vibration noise transmission path of an electric drive system according to claim 4, characterized in that: In step 4-2), the external excitation includes electromagnetic excitation and tooth surface surrounding parameter meshing excitation, and the input interval of the electromagnetic excitation is ≤0.2deg, and the input interval of the tooth surface surrounding parameter meshing excitation is ≤0.1deg.

6. The method for evaluating the vibration noise transmission path of an electric drive system according to claim 1, characterized in that: In step 5), the single bearing force order excitation force determined in step 4) is loaded into the finite element model, and the node vibration velocity and equivalent sound power of each analysis surface are calculated. The specific steps are as follows: 5-1) Loading the single bearing force order excitation force determined in step 4) to the finite element model to obtain the vibration velocity of all nodes in each analysis surface; 5-2) Based on the vibration velocities of all nodes within each analysis surface, the specific formula for obtaining the equivalent sound power of each analysis surface is as follows: Where P is the equivalent sound power; d is the gain coefficient; ρ is the air density under calculation conditions, in kg / m 2 ; c is the sound pressure wave velocity under calculation conditions, in m / s; Ai is the equivalent area of ​​the i-th node, in m 2 ; vi is the vibration velocity of the i-th node in the analysis surface, in m / s.

7. The method for evaluating the vibration noise transmission path of an electric drive system according to claim 1, characterized in that: In step 6), the calculation formula for the mean vibration acceleration of the mount under a single bearing force order excitation force is as follows: Where a F l is the average vibration acceleration of K nodes; Fl is the excitation force of a single bearing force order; K is the number of nodes; amx is the vibration acceleration of the mth node in the X direction, amy is the vibration acceleration of the mth node in the Y direction, and amz is the vibration acceleration of the mth node in the Z direction.

8. The method for evaluating the vibration noise transmission path of an electric drive system according to claim 1, characterized in that: In step 7), the specific method of establishing the sound radiation energy curve diagram and the suspension vibration response hotspot diagram based on the calculation results of the electric drive system acoustic vibration response is as follows: 7-1) The specific steps for establishing the sound radiation energy curve are as follows: 7-1-1) Based on the equivalent sound power and combined with the following formula, the equivalent amplitude of the sound pressure level is obtained: Where Pa is the equivalent amplitude of the sound pressure level; P is the equivalent sound power; 7-1-2) A frequency threshold is provided for determining the method for correcting the equivalent amplitude of the sound pressure level. The A-weighted sound pressure level is used and the equivalent amplitude of the sound pressure level is corrected by the following method to obtain the corrected equivalent amplitude of the sound pressure level: ① When the order frequency of interest is less than or equal to the frequency threshold, the following formula is used to perform an equivalent correction on the equivalent amplitude of the sound pressure level: Where Pa1 is the corrected equivalent amplitude of the sound pressure level; Pa is the equivalent amplitude of the sound pressure level; P is the equivalent sound power; ② When the order frequency of interest is greater than the frequency threshold, the following formula is used to perform an equivalent correction on the equivalent amplitude of the sound pressure level: Pa1=Pa-8 Where Pa1 is the corrected equivalent amplitude of the sound pressure level; Pa is the equivalent amplitude of the sound pressure level; 7-1-3) Create a sound radiation energy curve based on the order frequency of interest and the corrected sound pressure level equivalent amplitude; 7-2) Based on the mean vibration acceleration and the excitation force path, establish a hotspot map of the suspension vibration response under each bearing excitation path at each order.

9. The method for evaluating the vibration noise transmission path of an electric drive system according to claim 8, characterized in that: In step 8), the sound radiation energy curve is used to obtain the corrected sound pressure level equivalent amplitude superposition and Pall of each order of interest surface, and based on the sound radiation energy curve and the corrected sound pressure level equivalent amplitude superposition and Pall, the sound radiation contribution of each interest surface of the electric drive system is evaluated.

10. The method for evaluating the vibration noise transmission path of an electric drive system according to claim 1, characterized in that: In step 8), based on the mount vibration response hotspot map, the contribution of the excitation under each unidirectional transmission path to the vibration acceleration of the mount installation point is evaluated as follows: ① Using the mount vibration response heat map and the following formula, the vivid acceleration level under each excitation path is obtained: Where Dlf is the vibration acceleration level under the excitation force of the first single bearing force order; a F l is the mean vibration acceleration of K nodes; ② Superimpose the vibration acceleration levels under all excitation paths to obtain the sum of the vibration acceleration energy Dall at the suspension mounting point under all path excitations; ③ Based on the suspension vibration response hotspot map, the superposition of the vibration acceleration energy of the suspension installation point under all path excitations, and the contribution of Dall to the vibration acceleration of the suspension installation point are evaluated.

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