Powertrain Mounting System Research Articles

Stochastic assessment of electric powertrain whining noise under early-stage design uncertainties

Despite the advantage of being quieter than traditional internal combustion engine vehicles, electric vehicles are often distinguished by high-frequency tonal components, which can be perceived as unpleasant to the occupants and the environment. To ensure optimal acoustic comfort in electric vehicles, it is important to analyze the NVH behavior of e-powertrains during the early stages of the design process which poses inherent uncertainties, such as varying operating conditions, partial knowledge of design parameters, dispersion in measurement-based data, etc. To effectively address these uncertainties, it is necessary to use fast and comprehensive stochastic models during the design phase. In this work, a probabilistic framework is presented to estimate the electric powertrain’s interior whining noises considering the structure-borne contribution. Hence, two different stochastic metamodels are developed for efficient quantification and propagation of uncertainties from electric motor stage to powertrain mounting system. Multivariate Bayesian regression models help to incorporate prior knowledge on the uncertain parameters and generate the respective posterior distributions using Markov chains Monte Carlo (MCMC) techniques. For this particular application, the data is generated through weakly-coupled multi-physical domains estimated using semi-analytical approaches and combined with measured vehicle transfer functions. Importantly, the validation of each domain is conducted separately to ensure accurate representation. The results obtained from the developed probabilistic framework will aid in the early design stages by guiding engineers in making informed decisions to optimize NVH performance.

Optimization of Idle Vibration Characteristics of Powertrain Mounting System

Optimization of Idle Vibration Characteristics of Powertrain Mounting System

Hybrid Electric Vehicle Powertrain Mounting System Optimization Based on Cross-Industry Standard Process for Data Mining

The meticulously engineered powertrain mounting system of hybrid electric vehicles plays a critical role in minimizing vehicle vibrations and noise, thereby enhancing the longevity of vital powertrain components. However, developing and designing such a system demands substantial time and financial investments due to intricate analysis and modeling requirements. To tackle this challenge, this study integrates data mining technology into the design and optimization processes of the powertrain mount system. The research focuses on the powertrain mounting system of a transverse four-cylinder hybrid electric vehicle, employing the CRISP-DM (Cross-Industry Standard Process for Data Mining) methodology to establish a data-mining prediction model for mounting stiffness. This model utilizes three data mining algorithms—Multi-SVR, MRTs, and MLPR—to assess their predictive accuracy concerning mounting system stiffness estimation. A comparative analysis reveals that the MRTs algorithm outperforms others as the most effective prediction model. The proposed predictive model elucidates the quantifiable correlation between vibration isolation performance and installation stiffness, overcoming complexities associated with traditional modeling approaches. Applying this model in powertrain mounting system design showcases the efficacy of the CRISP-DM-based approach, significantly enhancing design efficiency without compromising prediction accuracy.

Influence of Exhaust Aftertreatment System on Powertrain Vibration Behavior

<div>NVH refinement of commercial vehicles is the key attribute for customer acceptance. Engine and road irregularities are the two major factors responsible for the same. During powertrain isolators’ design alone, the mass and inertia of the powertrain are usually considered, but in practical scenarios, a directly coupled subsystem also disturbs the boundary conditions for design. Due to the upgradation in emission norms, the exhaust aftertreatment system of modern automotive vehicles becomes heavier and more complex. This system is further coupled to the powertrain through a flexible joint or fixed joint, which results in the disturbance of the performance of the isolators.</div> <div>Therefore, to address this, the isolators design study is done by considering a multi-body dynamics model of vehicles with 16 DOF and 22 DOF problems, which is capable to simulate static and dynamic real-life events of vehicles. Design indicators are thoroughly analyzed and validated through the rigid body modes and real field events of the vehicle. As most of the research is done for four-point mounting powertrain systems by considering 6 DOF or 12 DOF in commercial vehicles but a novel approach with a 22 DOF model is proposed in this study to predict the impact of the inclusion of the exhaust aftertreatment system on torque roll axis and rigid body modes decoupling.</div> <div>The results of the proposed system show that the rigid body mode decoupling of the powertrain system improved and consequently the overall NVH performance of the vehicle in real life is further improved. Therefore, it is suggested from the study that ignoring the inclusion of the exhaust aftertreatment system in the powertrain mounting system design reduces the NVH performance of the vehicle, hence it is recommended to include it in the early phase of design.</div>

Optimization of a commercial vehicle powertrain mounting system based on new rubber mounts

In order to improve the vibration isolation, environmental adaptability and development efficiency of rubber mounts, a novel rubber mount with adjustable parameters such as stiffness, support height and limit distance was proposed, and its structural composition and working principle were described. And then, a commercial vehicle was taken as the research object to conduct the calculation of mounts stiffness by employing the energy decoupling method and genetic algorithm. On the basis of the influence of cone angle, thickness and height on the ratio of axial-radial stiffness, the detailed structural design of the mounts was carried out, and the relationship between the preloading displacement and axial-radial stiffness was studied by the method of theoretical calculation and test, which made the process of the stiffness adjustment more specific and accurate. Finally, the vibration isolation performance test of the Powertrain Mounting System (PMS) before and after stiffness adjustment was completed. Results show that the adjusted PMS indicates better vibration isolation performance at idle speed and slow acceleration in place, and the new mounts can effectively improve the vibration performance of vehicle, environmental adaptability of mounts and product development efficiency.

Uncertainty analysis of powertrain mounting systems with independent and correlated parameters based on multidimensional parallelepiped model

Uncertainty analysis of powertrain mounting systems with independent and correlated parameters based on multidimensional parallelepiped model

Analysis and Design of Rear Twin Electric Powertrain Mounting System in E-Up Boost

Abstract The paper focuses on analyzing and designing a mounting system for the modified rear powertrain of the E-up Boost. The initial section delves into the theoretical aspects, specifically examining the differing sources of vibration between internal combustion engines and electric powertrains. Following this, the subsequent section presents an in-depth analysis of the powertrain mounting system using ADAMS View. After the analysis is carried out, a robust mounting system is designed and verified through structural analysis.

Dynamic modeling and optimization for powertrain shake characteristics of electric powertrain system with hydraulic engine mounts

Poor designed powertrain mounting system can lead to severe resonance when road excitation frequency is consistent with the natural frequency of the powertrain mounting system, which results in vertical vibration of the vehicle. In addition, double-layer vibration isolation and hydraulic engine mount (HEM) are widely used for vibration attenuation of electric powertrain. This paper focuses on the vertical vibration of electric vehicles under road excitation. An analytic model of powertrain shake characteristics considering the amplitude-frequency dependent nonlinearity of HEMs is established. Furthermore, the proposed nonlinear model is experimentally validated through rigid body modal test of the powertrain. Numerical simulation is carried out to investigate the influence of HEM parameters on powertrain shake characteristics. Simulation results demonstrate that the effective pumping area, upper chamber stiffness and inertia track effective cross-sectional area, and length of HEM have obvious impact on powertrain shake characteristics. Under the premise of ensuring vibration isolation performance under other conditions, optimization of the above HEM parameters can reduce peak value of car body vibration under road excitation and thus improve ride comfort.

Driveline System Effects on Powertrain Mounting Optimization for Vibration Isolation under Actual Vehicle Conditions

<div>Vehicle vibration is the key consideration in the early stage of vehicle development. The most dynamic system in a vehicle is the powertrain system, which is a source of various frequency vibration inputs to the vehicle. Mostly for powertrain mounting system design, only the uncoupled powertrain system is considered. However, in real situations, other subsystems are also attached to the powertrain unit. Thereby, assuming only the powertrain unit ignores the dynamic interactions among the powertrain and other systems. To address this shortcoming, a coupled powertrain and driveline mounting system problem is formulated and examined. This 16 DOF problem is constructed around a case of a front engine-based powertrain unit attached to the driveline system, which as an assembly resting on other systems such as chassis, suspensions, axles, and tires. First, the effect of a driveline on torque roll axis and other rigid body modes decoupling is examined analytically in terms of eigensolutions and frequency responses. It is observed from the analysis that when the optimized uncoupled powertrain system is introduced in real vehicle conditions, the vibration isolation level of the powertrain mountings gets degraded. Then, a new improved approach of considering coupled powertrain and driveline systems in the initial design phase itself is proposed. The mounting system parameters such as mount location, mount orientation angle, and stiffness rate are optimized and redesigned for the proposed system. The results of the redesigned system show that the decoupling of the rigid body mode parameters is improved and consequently powertrain vibration performance is also improved in static and dynamic conditions of the vehicle. Overall, the findings of this study suggest that considering the driveline along with the powertrain as a coupled system at the early phase of the mounting system design itself improves the vibration performance of the vehicle during real-life situations.</div>

Optimization of Vehicle Powertrain Mounting System Based on Generalized Inverse Cascade Method under Uncertainty

This paper presents a summary of the optimization design process for a multi-objective, two-level engineering problem, utilizing the generalized inverse cascade method under uncertainty. The primary objective is to enhance the vibration isolation performance of a mounting system, considering the influence of uncertain factors on its stiffness. The focus is on determining the value range of the design variables at the bottom layer, ensuring that the design goal is met with a specified confidence level. To illustrate the application of this methodology, the optimization design of a powertrain mount is used as a case study. A data-driven approach is adopted, establishing a quantitative mapping relationship between mount stiffness, force transmission rate, modal decoupling rate, and other design indicators. This is achieved through the development of a CRBM-DBN approximate model, which combines Conditional Restricted Boltzmann Machines (CRBMs) and a Deep Belief Network (DBN). Additionally, an intelligent optimization algorithm and interval search technology are employed to determine the optimal design interval for the mount stiffness. Simulation and experimental verification are conducted using selected parameter combinations. The results demonstrate notable improvements in the vibration isolation performance, modal decoupling rate, and vehicle NVH performance when compared to the original state. These findings provide valuable insights for the interval optimization design of similar multi-objective, as well as two-level engineering problems, serving as useful references for future research and applications.

Thermal failure analysis and control algorithm improvement for the active controlled mount with consideration of thermal–magnetic coupling

This paper proposes an improved narrowband filtered-x least mean square(FxLMS) algorithm to overcome the thermal failure problems of the active controlled mount(ACM). Firstly, the temperature-rising model and the thermal demagnetization model of the ACM are respectively developed. Combining these two models with the powertrain mounting system model, an analytical method is established for the thermal–magnetic coupling analysis of the ACM. Then a numerical simulation is carried out to obtain the permanent magnet(PM) temperature and the coil current. The ACM failure problem is discussed according to the working point trajectory. Finally, an improved algorithm is proposed. This algorithm is able to overcome the thermal failure problems by sacrificing part of the vibration isolation performance. The effectiveness of this algorithm is validated by numerical simulations and a comparison with conventional algorithms.

Hybrid uncertainty analysis and optimisation based on probability box for bus powertrain mounting system

In engineering practice, the bus powertrain mounting system (BPMS) may have both epistemic and aleatory uncertainty under the influence of manufacturing, measurement, and assembly errors. The hybrid uncertainty in BPMS may result in over-design or insufficient design. Therefore, the probability box (p-box) model, which can handle both aleatory and epistemic variables, is introduced into the uncertainty analysis of BPMS. Considering the elastic connection between the compressor and powertrain, a 12-degree-of-freedom dynamic model is constructed to calculate the inherent characteristic of BPMS. A rejection sampling method based on the fast envelope function (RSMBFEF) is proposed to propagate the hybrid uncertainties. Then double-loop Monte Carlo method is used to be compared with RSMBFEF. To reduce the number of uncertainty analyses, a two-step uncertainty optimisation method is proposed. Finally, the proposed method's efficacy and accuracy are verified through a numerical case. The applicability of the p-box model is illustrated by comparing it with the BPMS model with only pure aleatory or pure interval variables.

Development of powertrain mounting system for high frequency characteristics optimisation in electric vehicles

Development of powertrain mounting system for high frequency characteristics optimisation in electric vehicles

Development of powertrain mounting system for high frequency characteristics optimisation in electric vehicles

Development of powertrain mounting system for high frequency characteristics optimisation in electric vehicles

Finite Element Model refinement of powertrain mount brackets for estimating natural frequencies

Natural frequencies of powertrain mount brackets have great influences on NVH (Noise, Vibration, Harshness) performances of a Powertrain Mount System. Usually, large relative error between the measured- and the estimated natural frequencies using finite element analysis existed. In this paper, a methodology to refine the mount bracket finite element model is proposed based on global response surface method and optimization methods. The material parameters uncertainty and the constraint boundary (bolt joint) are taken into account for model update parameters, since they are the main factors affecting the accuracy of the calculated natural frequencies of bracket. The material parameters are optimized by minimizing the errors between calculated and measured un-constrained natural frequencies of the mount bracket. The bolt joint are modeled using the equivalent stiffness of spring element that are optimized by minimizing the deviations between the calculated and measured constrained natural frequencies of the bracket. Another mount bracket is used to obtain natural frequencies calculated using the refined finite element model and measured, and the comparisons of the calculated versus the measured natural frequencies shown that the refined finite element model of mount bracket with identified material parameters and boundary stiffness values exhibits high prediction precision for estimating natural frequencies of the brackets. This indicates that the proposed finite element model refinement methodology for mount bracket is effective and can help the NVH engineers to design larger natural frequencies of mount brackets.

Optimization of engine and transmission mounting system for a V6 front wheel drive vehicle

Engine mounts helps to attach power train with the frame of the vehicle. The engine mounts help to keep the power- train in its position with the SUV chassis as vehicle experiences several torque loads and inertial loads. The mounting system helps in controlling the motion of the engine and transmission unit, preventing it from physical contact with other components of the vehicle system from sudden impact due to vibrations. The power train Mounting system helps in several ways to keep the engine and transmission unit firmly in its position during vehicle motion and helps in better drivability. Engine along with transmission unit con– tributes 25% of total weight of vehicle, it is important to isolate noise and vibration generated in the engine entering into the vehicle cabin, as power train is the source of vibration in the vehicle. So, it is important to study and investigate rigid body mode shapes for the engine and transmission unit for particular position of mounting unit and spring stiffness. This paper investigates the engine mounting system location and spring stiffness for a vertically mounted v8 engine. The engine and transmission unit mounted on vehicle chassis by elastomeric bushings. The bushing acts as spring mass damper system, helping in isolation of vibration and noise entering into cabin also prevents physical contact of engine with other critical vehicle components. Design of experiments approach is used to study effects of design variables. By varying mount location and stiffness rates the effects of these variable on the power train mounting system is studied and appropriate mounting location and stiffness rates is suggested to improve overall NVH performance of the power train.

Analysis of the Influence of a Powertrain Mounting System on a Dual-Clutch Transmission Vehicle under Typical Working Conditions

The unsuitably designed powertrain mount may cause jittering and shrugging during the starting and shifting processes of the vehicle, which seriously affects the comfort of using the vehicle. However, the influence of mounts on vehicles has been neglected in previous studies. In view of the above problems, this study establishes a DCT vehicle coupling dynamic model, considering six degrees of freedom of the powertrain mount and the engine dynamic torque, nonlinear characteristics of a dual-mass flywheel, time-varying stiffness of gear systems, and other factors. Furthermore, the effect of mounts on the longitudinal dynamic characteristics of the vehicle is studied during the starting, shifting, and tip-in/tip-out process. The results show that under typical working conditions, the mount and its stiffness and damping affect the fluctuation frequency and amplitude of the jerk. When the torque of the vehicle transmission system changes greatly, such as under starting and tip-in/tip-out conditions, the mount has a great impact on the dynamic performance of the vehicle. Simultaneously, the engine torque fluctuation can act on the vehicle through the mount, which has an impact on the jerk of the vehicle. A comparison with vehicle test results reveals that the DCT coupling dynamic model can reflect the law of the effect of the mount on the vehicle performance and verify the rationality of the model. Under typical working conditions, when the influence of the mount is not considered in the vehicle dynamic’s modeling, there is a large error of the jerk between the simulation results and the actual situation. The results provide a reference for optimizing the parameters of the mount and improving the dynamic characteristics of DCT vehicles.

Design optimization of engine mounting system for a modular electric vehicle platform with different powertrain characteristics

In recent days, there is much focus on the modularity of the platform to reduce the cost and improve the system-level design efficiency. In this paper, a study has been done for various non-linear input torque (different powertrain) and optimization with a modular powertrain mounting system where only stiffness is varied to achieve the optimization goal. Here, the optimization goals are maximization of kinetic energy distribution to improve the decoupling rate and minimization of powertrain CoG movement under torque. HEEDS and MATLAB optimization tools are used for analysis. First, three different powertrains are considered individually for optimization. Then, all three powertrains for a particular location on the modular platform are optimized with different mount stiffness. Different mount stiffnesses are chosen in such a way that the stiffness can be achieved only by hardness adjustment or minimum design modification without any change in complete mount design. Proposed results show that a properly chosen mounting system can address the platform modularity quite quickly.

Systems Design Using Solution-Compensation Spaces with Built-In Tolerance Applied to Powertrain Integration

AbstractComplexity in systems design can be reduced by computing permissible ranges for some crucial design variables that need to be defined in an early design phase. These ranges are calculated such that there is sufficient tolerance for the remaining design variables in later design phases, while still achieving the overall system design goals. A new algorithm for this approach is presented and applied to the design of a vehicle powertrain mount system. The results show large permissible ranges for mount positions while maintaining sufficient tolerance for mount stiffnesses.

Uncertainty and correlation propagation analysis of powertrain mounting systems based on multi-ellipsoid convex model

In engineering practice, uncertainty and correlation may coexist in both input parameters and output responses of the powertrain mounting system (PMS) of a vehicle. A methodology is developed for the uncertainty and correlation propagation analysis of the inherent characteristics of PMSs in this research. In the proposed methodology, the multi-ellipsoid convex model is introduced to quantify multiple groups of uncertain parameters with correlation, where dependent and independent uncertain parameters are considered simultaneously. In the uncertainty propagation analysis, it aims to calculate the interval bounds of system responses. To perform uncertainty propagation analysis, the Monte Carlo uncertainty analysis (MCUA) method is firstly presented based on Monte Carlo simulation, and the first-order perturbation-central difference-Lagrange multiplier (FPCDLM) method and the second-order perturbation-central difference-Lagrange multiplier (SPCDLM) method are then derived to promote the computational efficiency. In the correlation propagation analysis, it aims to compute the correlation between different system responses. To conduct the correlation propagation analysis, the Monte Carlo correlation analysis (MCCA) method is firstly proposed and the second-order perturbation correlation analysis (SPCA) method are then developed to enhance the computational efficiency. Next, the whole procedures for uncertainty and correlation propagation analysis of PMS are established by combining the above uncertainty analysis and correlation analysis methods, and the elliptical domain of any two system responses can be obtained. Finally, numerical examples of the PMS of an electric vehicle are provided to demonstrate the effectiveness of the proposed methodology.