Application of Sensitivity Analysis to the Development of High Performance Adaptive Hydraulic Engine Mounts

Summary In this paper, the sensitivity analysis is applied to the development of high performance adaptive hydraulic mounts. The analysis allows us to select the most effective design parameters for tuning an adaptive mount to different road and engine conditions. It is shown that in the low frequency road excitation, the upper chamber compliance and inertia of the fluid column in the inertia track are the most influential properties in changing the dynamic stiffness of the hydraulic mount. These properties for the high frequency engine excitations are the upper compliance and the inertia of the fluid column of the decoupler. For tuning the adaptive mount to different road and engine excitation, a global optimization technique is used to find the magnitude of the adjusting parameters to minimize objective functions in low and high frequency excitations. The results indicate significant improvement over conventional hydraulic mounts. It is further shown that when the upper compliance is used as the adjusting parameter, a simple on-off control which is triggered by the engine revolution and vehicle speed is sufficient for tuning the adaptive mount.     

发动机液压悬置低频模型参数识别方法的研究

根据悬置低频振动模型,提出了基于DE算法的发动机液压悬置模型识别方法,由简单的低频正弦激振试验直接估计模型的关键参数值,完成模型的参数识别。基于上述理论和试验相结合的模型识别方法可以代替组件试验,识别结果可直接用于复杂结构悬置元件的动特性预测和整车NVH性能研究。     

On the Design and Development of a Magneto-Rheological Mount

This paper evaluates the performance of a Magneto-Rheological (MR) mount. The mount incorporates MR fluid in a conventional fluid mount to open and close an inertia track between the fluid chambers of the mount. It is shown that such switching of the inertia track improves the mount's isolation effect by eliminating the large transmissibility peak that commonly exists at frequencies larger than the notch frequency for conventional fluid mounts. The switching frequencies of the MR mount are evaluated based on the parameters of the mount. A simple control scheme for switching the mount between the open and closed states is proposed, and the performance of the controlled mount is compared with conventional mounts. A sensitivity analysis is conducted to evaluate the effect of parameter errors in estimating the switching frequencies and mount performance. The results show that the switching frequencies can be accurately determined from mount parameters that are easily measured or estimated.     

On the Design and Development of a Magneto-Rheological Mount

This paper evaluates the performance of a Magneto-Rheological (MR) mount. The mount incorporates MR fluid in a conventional fluid mount to open and close an inertia track between the fluid chambers of the mount. It is shown that such switching of the inertia track improves the mount's isolation effect by eliminating the large transmissibility peak that commonly exists at frequencies larger than the notch frequency for conventional fluid mounts. The switching frequencies of the MR mount are evaluated based on the parameters of the mount. A simple control scheme for switching the mount between the open and closed states is proposed, and the performance of the controlled mount is compared with conventional mounts. A sensitivity analysis is conducted to evaluate the effect of parameter errors in estimating the switching frequencies and mount performance. The results show that the switching frequencies can be accurately determined from mount parameters that are easily measured or estimated.     

液压悬置动特性实验分析及模型修正方法研究

在综合分析现有悬置非线性数学模型的基础上,重点分析了惯性通道弯管损失系数对悬置动态性能的影响,建立了包含惯性通道弯管损失系数的更精确的数学模型,并探讨了悬置及橡胶主簧动态、静态特性的试验测试方法,建立了相应的测试平台,对相同工况下液压悬置和橡胶主簧动、静态特性进行了测试及对比分析。将橡胶主簧的实验数据应用于所建的模型中,仿真结果和实验分析表明本模型具有更高的精度。     

Semi-active engine mount design using auxiliary magneto-rheological fluid compliance chamber

Engine mounts are used in the automotive industry to isolate engine and chassis by reducing the noise and vibration imposed from one to the other. This paper describes modelling, simulation and design of a semi-active engine mount that is designed specifically to address the complicated vibration pattern of variable displacement engines (VDE). The ideal isolation for VDE requires the stiffness to be switchable upon cylinder activation/deactivation operating modes. In order to have a modular design, the same hydraulic engine mount components are maintained and a novel auxiliary magneto-rheological (MR) fluid chamber is developed and retrofitted inside the pumping chamber. The new compliance chamber is a controllable pressure regulator, which can effectively alter the dynamic performance of the mount. Switching between different modes happens by turning the electrical current to the MR chamber magnetic coil on and off. A model has been developed for the passive hydraulic mount and then it is extended to include the MR auxiliary chamber as well. A proof-of-concept prototype of the design has been fabricated which validates the mathematical model. The results demonstrate unique capability of the developed semi-active mount to be used for VDE application.     

基于流固耦合有限元法的汽车发动机液力悬置动力学分析

介绍了车载发动机液力悬置流固耦合的有限元分析法,模拟了液力悬置的动态响应。通过瞬态时域响应的模拟结果,计算了液力悬置的动态性能。在计算过程中使用ALE方法进行坐标变换,有效解决了流体力学和结构动力学在坐标系上的不一致问题。计算过程无须估算或测试液力悬置的流体阻尼,无须测量橡胶主簧的体积刚度,可以得到液力悬置在时域内的动态响应,仿真结果与试验测试结果吻合较好。     

Computational model of conventional engine mounts for commercial vehicles: validation and application

In this paper, a computational model of conventional engine mounts for commercial vehicles comprising elastic, viscous and friction functional components, which expresses the nonlinear behaviour of the dynamic stiffness and damping of mounts as functions of both frequency and amplitude of excitation, is developed. Optimisation approach is implemented to identify model parameters using measurement data. The developed model has been validated against measurement data for harmonic excitations with a frequency range of 5–100 Hz and an amplitude range of 0.025–2 mm employing three different engine mounts used in heavy trucks. The model shows good and admissible agreement with measurement data keeping the tolerance of estimation below 11%. Simulations of engine vibration dynamics are presented with both proposed model and commonly applied Kelvin–Voigt model of the mounts. The developed model can be used in complete vehicle advanced dynamic analyses and also in the design of semi-active and active engine mounting systems for commercial vehicles.     

半主动控制惯性通道式液力悬置开发

介绍了一种惯性通道半主动控制式液力悬置的设计开发。该液力悬置不改变橡胶主簧刚度和液体黏度,随发动机转速变化,由步进电机控制旋转阀的旋转角度,改变惯性通道的工作段(各段具有不同的长度),从而改变液力悬置的动态特性,使发动机—悬置系统的振动传递率最小。装车试验表明,所设计悬置具有较好的宽频带减振隔振性能。     

惯性通道—解耦膜式液压悬置动特性分析

本文以Ａｕｄｉ１００轿车总成液压悬罩为例，建立了惯性通道－解耦膜式液压悬的非线；力的非线性力学模型和数学模型，对其原点动特性和跨点动特性进行仿真计算，经与试验结果相比较，二者吻合良好。     

Optimal design of an engine mount using an enhanced genetic algorithm with simplex method

This study provides an analysis of the applications of optimization routines for designing fluid mounts. After summarizing the concept of fluid mounts and their dynamic characteristics, we review the importance of the notch and resonance peak that occur in dynamic stiffness of fluid mounts. Fluid mounts are tuned for specific application so that their notch frequency coincides with the disturbance frequency, by selecting the proper parameters for the mount. Additionally, the mount parameters are selected such that the notch remains as deep (close to zero) as possible and the resonance peak is kept as short as possible. The notch depth and resonance peak present opposing requirements for the selection of mount parameters in the sense that lowering one will result in increasing the other. Using a bond graph model, this study will evaluate the effect of various parameters on the mount notch depth and resonance peak height characteristics. The results show that different parameters can have a varying effect on the notch frequency and depth, as well as the resonance frequency and peak height. The results of the study are extended by examining the effectiveness of two different optimization methods—namely, the Enhanced Genetic Algorithm (EGA) and Sequential Quadratic Programming (SQP)—for selecting the combination of parameters that can yield the deepest notch and shortest resonance peak. Using two different design cases, the study shows that SQP exhibits much more sensitivity to the initial conditions that are selected for the mount parameters than EGA. Both methods, however, are able to converge to an optimal solution within the constraints that are selected for the parameters. For both cases, EGA is able to converge to the set of parameters that provide a deep notch and a short resonance peak.     

汽车发动机悬置系统动刚度模态分析

建立了基于悬置元件怠速工况下动刚度的发动机悬置系统MATLAB力学模型.同时由LMS实验模态分析系统测得了发动机实际工况下的运行模态参数,并以模态置信度对其进行了验证.与静刚度模型相比,以悬置元件动刚度建立的模型,其动态参数与运行模态参数更为接近,表明动刚度模型能更好地模拟悬置系统实际工况下的动态特性.     

Engine mount optimisation for vibration isolation in motorcycles

This paper presents a comprehensive model to capture the in-plane dynamics of a motorcycle system to evaluate the quality of its vibration isolation, and the design of an engine mount system. The model consists of two main structural components, the frame and the swing-arm, as well as the power-train assembly, engine mounts connecting the power-train to the frame, and the front-end assembly. The model accounts for frame and swing-arm flexibility using reduced order finite-element models. The power-train assembly is modelled as a rigid body connected to the frame through the engine mounts and to the swing-arm through a shaft assembly. The engine mounts are modelled as tri-axial spring-damper systems, and the front-end assembly is modelled as a lumped mass. The complete vehicle model is used to solve the engine mount optimisation problem, so as to minimise the total force transmitted to the frame while meeting packaging and other constraints. The mount system parameters – stiffness, position and orientation vectors – are used as design variables for the optimisation problem. The imposed loads include forces and moments due to engine imbalance as well as loads transmitted due to high amplitude, low frequency bump loads, through the tyre patch. Since packaging constraints play a significant role in a motorcycle layout, it is, therefore, important to determine the displacement envelope of the power-train under extreme loading conditions to ensure clearance with other components around the power-train. A motorcycle mount system should ideally be able to isolate the frame under steady-state loading conditions and at the same time limit the maximum excursion of the power-train under transient loading conditions.     

发动机振动隔离控制技术研究进展

介绍了发动机橡胶悬置、液压悬置、半主动悬置和主动悬置的工作原理,由于被动悬置不能满足运载器减振降噪的要求,半主动悬置和主动悬置已经成为发动机减振降噪发展方向;分析了悬置系统的动力学模型,包括悬置的动力学模型和控制系统的动力学模型;介绍了发动机振动隔离控制中几种主要的控制方法,包括模糊控制、神经网络控制、自适应控制和最优控制等。最后提出了发动机振动隔离控制目前存在的主要问题和发展动向。     

摩托车发动机弹性悬置减振研究

发动机弹性悬置可以减小发动机激振引起的摩托车振动,设计弹性悬置的主要工作是根据发动机质量、转动惯量和弹性元件刚度来计算弹性悬置发动机系统的自然频率,并修改弹性元件结构、材料以尽可能满足√2倍最高弹性悬置发动机系统自然频率小于发动机最低工作激振频率这一条件。试验结果表明,发动机弹性悬置具有很好的减振效果。     

汽车发动机主动隔振系统自适应控制

对压电作动器与液阻悬置组成的主动控制悬置进行了研究，采用前馈自适应控制对汽车发动机主动隔振系统进行了仿真。结果表明，相对于目前轿车上普遍采用的液阻悬置，主动控制悬置可以大大降低发动机在高速运转时向车身的振动传递，减小车内噪声，提高乘坐舒适性。     

Introducing a new semi-active engine mount using force controlled variable stiffness

This work introduces a new concept in designing semi-active engine mounts. Engine mounts are under continuous development to provide better and more cost-effective engine vibration control. Passive engine mounts do not provide satisfactory solution. Available semi-active and active mounts provide better solutions but they are more complex and expensive. The variable stiffness engine mount (VSEM) is a semi-active engine mount with a simple ON–OFF control strategy. However, unlike available semi-active engine mounts that work based on damping change, the VSEM works based on the static stiffness change by using a new fast response force controlled variable spring. The VSEM is an improved version of the vibration mount introduced by the authors in their previous work. The results showed significant performance improvements over a passive rubber mount. The VSEM also provides better vibration control than a hydromount at idle speed. Low hysteresis and the ability to be modelled by a linear model in low-frequency are the advantages of the VSEM over the vibration isolator introduced earlier and available hydromounts. These specifications facilitate the use of VSEM in the automotive industry, however, further evaluation and developments are needed for this purpose.     

基于 MFXLMS算法的汽车发动机振动主动控制研究

为了降低发动机工作时引起的整车振动,提出了使用多通道滤波x-LMS （MFXLMS） 算法作为主动悬置系统的控制算法。以发动机转速信号作为参考信号,主动悬置安装位置下方的两路加速度信号作为误差信号。根据算法完成试验平台搭建。采用白噪声电压信号作为输入激励,通过 LMS算法离线辨识得到主动悬置到加速度传感器的多路次级通道,在dSPACE上完成实车控制试验。试验结果表明,MFXLMS算法的运用显著降低了发动机不同转速工况下引起的测点加速度响应,提高了整车的乘坐舒适性。     

关于某动力总成悬置支架的优化设计

本文针对某动力总成悬置系统NVH性能道路试验中,全油门缓加速工况受发动机频率激振影响,某悬置主动侧支架发生共振,导致在260Hz左右产生车内结构噪声的情况,采用hypermech-nastran有限元软件建立该悬置支架的有限元模型对其模态进行分析,并根据模态分析结果对该悬置支架设计优化。最后通过道路试验结果验证悬置支架结构设计优化的正确性,可使整车在全油门缓加速工况260Hz附近的振动和车内噪声明显降低。     

Impact technique for measuring global dynamic stiffness of engine mounts

Engine mounts are used for engine vibration isolation. The dynamic performance of the mount depends on the orientation. Measurements of the dynamic properties of engine mounts are usually performed in the axial direction because of the problem related to actuator loading direction and set up costs. Impact technique is developed here to measure the dynamic driving point stiffness and driving point shear stiffness of engine mount in a single setup. The compressive and shear frequency-dependent stiffnesses are obtained in the vertical orientation. A transformation matrix is used to calculate the frequency-dependent stiffnesses and loss factors in other orientations. Three different designs of engine mounts are used to verify the accuracy of the transformation model. The correlation coefficient between calculation and measurement results show R²≥ 0.995 along the X- and Y-axes. For the Z-axis, mounts B and C showed R²≥ 0.95 and mount A 0.687 ≤ R²≤ 0.791.