Vehicle Engine Mount Research Articles

Development of a Systematic Methodology for Active Noise Control with Vehicle Engine Mounts Excitation

Active noise control (ANC) technology using speakers as actuators has an excellent performance, but since it generates anti-noise signals in a path completely different from the vehicle's noise source, performance can be greatly reduced at a location far from the error sensor, and this problem can get worse as the frequency to be controlled increases. Another approach is the vibration-based ANC technology that excites the body member around the engine mount and reduces acoustic error signals in a passenger compartment. This approach has the advantage of being effective even at a distance from the error sensor and reducing vibration and noise together when trying to cancel out the structure borne noise generated by the engine because the paths from the primary source and the secondary source to the interior are almost identical. This paper presents a systematic methodology for this vibration-based ANC technology to achieve high performance in vehicles. First, through noise reduction simulation, the number of error sensors, the location of actuators, the force requirements, and an appropriate system are proposed. Next, to improve performance even with a small number of actuators and limited power when applying this technology in vehicles, an algorithm using the control effort weighting parameter is introduced into the existing FxLMS algorithm and modelled on the controller. Finally, a noise reduction control test is performed in a vehicle under static and driving conditions, and the results are reviewed.

Idle shake vibration optimization of an engine mounting system through the practical application of transfer path analysis

This article presents a practical application of experimental transfer path analysis (TPA) for optimizing idle shake vibrations of a front-wheel-drive car with a transversely mounted four-cylinder diesel engine. Performance control of the vehicle engine mounting system must take into account the multiple dynamic interactions between the engine mounting system, subframe modes and the vehicle suspension. Experimental methods can be used in conjunction with simulations to design and optimize the engine mounting system. TPA is a powerful tool for the diagnosis of vibration and noise transmission via multiple solid paths. TPA allows a quick diagnosis of the engine mounting system performances on vehicle comfort. A strong synergy between numerical model and experimental data finally makes it possible to find better design alternatives, not necessarily obvious to the designer. This study is the guideline for an optimization of the engine mount noise vibration and harshness (NVH) performances by using a hybrid approach, combining an analytical approach and measurement data. First, a diagnosis of the transmission of structure-borne vibrations via the engine mounting system to the seat floor is done at constant idle speed. This method is used to rank individual engine mount contributions in the low-frequency vibration level inside the vehicle. Then, an original approach allows the optimization of the vibration level at idle speed by offsetting contributions of the engine mount paths by adding damping in the right engine mount. This approach has led to the design and validation of an original double inertia-track hydroelastic mount prototype which allows a 5-dB reduction on the seat floor vibration level. The future development of a new version is planned to confirm and optimized the obtained results. The length of the second inertia track will be increased to reach the targeted characteristics, and the adjustment system will be removed to respect the overall dimension constraints of the mount.

Elastomeric Component Fatigue Analysis: Rubber Fatigue Prediction and Correlation Comparing Crack Initiation and Crack Growth Methodologies

<div class="section abstract"><div class="htmlview paragraph">Many elastomeric components in automotive industry applications are subjected to dynamic service loads. Fatigue must be a consideration in the design of these components.</div><div class="htmlview paragraph">The two approaches in rubber fatigue analysis discussed in this study are the conventional crack initiation approach, based on continuum mechanics parameters versus life, and the crack growth approach, based on fracture mechanics parameters. These methodologies are demonstrated for a passenger vehicle engine mount here. Temperature effects are not considered since testing was performed at ambient room temperature and with a low frequency, typically less than 5 Hz.</div><div class="htmlview paragraph">The promising methodology for fatigue life prediction, discussed in this paper, is a critical plane approach based on crack energy density. Rainflow cycle counting method and Miner’s damage rule are used for load cycle characterization and damage accumulation respectively. A fracture mechanics approach is implemented based on specimen crack growth data.</div><div class="htmlview paragraph">This methodology is validated with component testing under constant amplitude experiments. Results are investigated through analysis of critical stress locations hot spots, life values, and strain states. Comparative results are presented. Numerical results show reasonable correlation with experimental data.</div></div>

Evaluation of Specialty Natural Rubbers for Engine Mount Application

An engine mount secures the engine of a vehicle to its chassis. Successful application of elastomeric mounts as vehicle engine mounts has been observed over the years. Epoxidised Natural Rubber (ENR) and Deproteinised Natural Rubber (DPNR) are specialty rubbers with a potential for application in the development of engine mounts. In this study, a blend comprising natural rubber (NR) and polybutadiene rubber (BR) is used to produce the Original Equipment Manufacturer (OEM) part. Epoxidised Natural Rubber (ENR25 and ENR50) and Deproteinised Natural Rubber (DPNR) developed by Malaysian Rubber Board were used and compared with NR by evaluating both physical and mechanical properties of the rubbers with different filler loadings. The physical properties of NR exhibited excellent results opposed to other rubbers. However, a blend of ENR25 and BR reflected good compression set at 100°C for 96 hours. The performance of an engine mount comprising a blend of ENR50 and BR is promising in reference to the excellent mechanical properties over that of other rubbers. Dynamic stiffness and damping characteristics of the engine mount play an important role to achieve vibration isolation with acceptable engine motion control in a vehicle’s engine mount system. It is perceived that engine mounts produced with a blend of ENR50 and BR can improve vibration effects in dynamic conditions.

Shell Analysis and Optimisation of a Pure Electric Vehicle Power Train Based on Multiple Software

Motor end cover mounting fracture is a problem recently encountered by novel pure electric vehicles. Regarding the study of the traditional vehicle engine mount bracket and on the basis of the methods of design and optimisation available, we have analysed and optimised the pure electric vehicle end cover mount system. Multi-body dynamic software and finite element software have been combined. First, we highlight the motor end cover mount bracket fracture engineering problems, analyse the factors that may produce fracture, and propose solutions. By using CATIA software to establish a 3D model of the power train mount system, we imported it into ADAMS multi-body dynamic software, conducted 26 condition analysis, obtained five ultimate load conditions, and laid the foundations for subsequent analysis. Next, a mount and shell system was established by the ANSYS finite element method, and modal, strength, and fatigue analyses were performed on the end cover mount. We found that the reason for fracture lies in the intensity of the end cover mount joint, which leads to the safety factor too small and the fatigue life not being up to standard. The main goal was to increase the strength of the cover mount junction, stiffness, safety coefficient, and fatigue life. With this aim, a topology optimisation was conducted to improve the motor end cover. A 3D prototype was designed accordingly. Finally, stiffness, strength, modal, and fatigue were simulated. Our simulation results were as follows. The motor end cover suspension stiffness increases by 20%, the modal frequency increases by 2.3%, the quality increases by 3%, the biggest deformation decreases by 52%, the maximum stress decreases by 28%, the minimum safety factor increases by 40%, and life expectancy increases 50-fold. The results from sample and vehicle tests highlight that the component fracture problem has been successfully solved and the fatigue life dramatically improved.

Modeling and simulation of longitudinal dynamics coupled with clutch engagement dynamics for ground vehicles

During the engagement of the dry clutch in automotive transmissions, clutch judder may occur. Vehicle suspension and engine mounts couple the torsional and longitudinal models, leading to oscillations of the vehicle body that are perceived by the driver as poor driving quality. This paper presents an effective formulation for the modeling and simulation of longitudinal dynamics and powertrain torsional dynamics of the vehicle based on non-smooth dynamics of multibody systems. In doing so friction forces between wheels and the road surface are modeled along with friction torque in the clutch using Coulomb’s friction law. First, bilateral constraint equations of the system are derived in Cartesian coordinates and the dynamical equations of the system are developed using the Lagrange multiplier technique. Complementary formulations are proposed to determine the state transitions from stick to slip between wheels and road surface and from the clutch. An event-driven scheme is used to represent state transition problem, which is solved as a linear complementarity problem (LCP), with Baumgarte’s stabilization method applied to reduce constraint drift. Finally, the numerical results demonstrate that the modeling technique is effective in simulating the vehicle dynamics. Using this method stick-slip transitions between driving wheel and the road surface and from the clutch, as a form of clutch judder, are demonstrated to occur periodically for certain values of the parameters of input torque from engine, and static and dynamic friction characteristics of tire/ground contact patch and clutch discs.

Functional Overview of Hydraulic Vehicle Engine Mount Classification

Functional Overview of Hydraulic Vehicle Engine Mount Classification

Automotive vehicle engine mount based on an MR squeeze-mode damper: modeling and simulation

The study investigates the performance of a semi-active vehicle engine mount incorporating an MR damper working in the squeeze mode (MRSQD), summarising its design, operating principles and key characteristics. The mathematical model of the mount is formulated based on the newly developed MRSQD. Two control algorithms are proposed for MRSQD control. The first algorithm (ALG1) uses the inverse model of the engine-frame system, the other is the sliding mode algorithm (ALG2). The effectiveness of the engine mount system is demonstrated in computer simulation.

A magneto-rheological fluid mount featuring squeeze mode: analysis and testing

This paper presents a mathematical model for a new semi-active vehicle engine mount utilizing magneto-rheological (MR) fluids in squeeze mode (MR mount in short) and validates the model by comparing analysis results with experimental tests. The proposed MR mount is mainly comprised of a frame for installation, a main rubber, a squeeze plate and a bobbin for coil winding. When the magnetic fields on, MR effect occurs in the upper gap between the squeeze plate and the bobbin, and the dynamic stiffness can be controlled by tuning the applied currents. Employing Bingham model and flow properties between parallel plates of MR fluids, a mathematical model for the squeeze type of MR mount is formulated with consideration of the fluid inertia, MR effect and hysteresis property. The field-dependent dynamic stiffness of the MR mount is then analyzed using the established mathematical model. Subsequently, in order to validate the mathematical model, an appropriate size of MR mount is fabricated and tested. The field-dependent force and dynamic stiffness of the proposed MR mount are evaluated and compared between the model and experimental tests in both time and frequency domains to verify the model efficiency. In addition, it is shown that both the damping property and the stiffness property of the proposed MR mount can be simultaneously controlled.

PHYSICAL MODEL OF VEHICLE ENGINE MOUNT WITH MAGNETORHEOLOGICAL DAMPER

A physical model of a vehicle engine mount incorporating a magnetorheological (MR) damper in squeeze mode is investigated and the structural design and operating characteristics of the MR damper are provided. The mathematical model of an engine mount is formulated. Kinematic excitations are assumed to be those emulating road profile-chassis (car body) interactions. Simulations of engine vibration are performed to determine the efficiency of the proposed engine mount. Conclusions are drawn concerning the potential applications of the MR damper in vehicle engine mounts.

온도변화를 고려한 고무엔진마운트의 동특성 변동성 해석

Vehicle vibrations arise from engine and road surface excitations. The engine mount system of a passenger car sustains the engine weight and insulates the excitation force from the engine system. The dynamic properties of viscoelastic material used for the vehicle engine mounts have large variation due to environmental factors such as environmental temperature and humidity etc. The present study aims to investigate the variability of dynamic characteristics in rubber engine mounts considering both environmental temperature change and material model errors/uncertainty. The engine mounts for a passenger car were modeled using finite element method. Then, the dynamic stiffness variability of the engine mounts were estimated using Monte Carlo simulation method. In order to estimate the variations in the storage and loss moduli of the viscoelastic materials, the material properties of the synthetic rubber were expressed as a fractional-derivative model. Next, in order to simulate the uncertainty propagation of the dynamic stiffness for the engine mounts due to the storage and loss moduli variations, the Monte Carlo simulation was used. The Monte Carlo simulation results showed large variation of the engine-mount stiffness along frequency axis.

Non-linear dynamics of a whole vehicle finite element model using a harmonic balance method

The aim of this paper is to apply the Harmonic Balance Method (HBM) to a finite element model of a complete vehicle (body, engine and engine mounts) to calculate the non-linear response of the assembly. The non-linear effects come from the amplitude-dependent stiffness of the engine mounts. First, the HBM is presented. A condensation process on the non-linear degrees-of-freedom is also proposed. This process reduces the original non-linear system by focusing only on the solution of the non-linear equations associated with the system’s non-linear components. Second, the engine mount stiffness dependency with amplitude is measured on a test bench to estimate a polynomial stiffness law. Finally, the numerical analysis is performed to analyse the non-linear response of the whole vehicle using the HBM algorithm with appropriate condensation located only on the non-linear coordinates of the system to minimise computer time.

Testing and Analysis on Vibration Isolation Performance of Vehicle Engine Mounting System

Aiming at the vibration test of the power train mounting system of certain light truck, a vibration test is performed, and vibration response at each testing point of the system is obtained in different conditions. Data is processed based on Matlab software, to display the time domain and the frequency domain response in an image way in each testing condition. The energy transfer efficiency of each mounting point, the vibration frequency domain response property, and the vibration intensities of the variable-speed joystick and the steering wheel in three directions are analyzed, a parameter design optimize proposal on the mounting system is proposed, and the vibration isolation effect can be improved by reasonably selecting parameters.

Active force cancellation of a near resonance vibrating system using robust H<SUB align="right">∞ control

In this study, the active force cancellation performance of a robust H∞ controller is investigated on a near resonance vibrating system consisting of a rotating machine hard mounted on a flexible base. This configuration and phenomenon can be present in vehicle engine mounts. The model of the vibrating system was first identified experimentally. The uncompensated system frequency response is then used to design the controller. The control objective is to reduce the system (RMS) gain. The effectiveness of the controller has been demonstrated experimentally through implementation on a digital signal processor. Results show reductions of the measured RMS transmitted forces at different mount locations when the machine is operated at speeds near the principal mode of vibration. However at frequency where the vibration is not significant, the reduction in transmitted force level can be minimal.

Vibration Control and Design of Vehicle Engine Mount Activated by Magnetorheological Fluid

Magneto-rheological (MR) fluid mount demonstrates excellent performance of vibration isolation in a wide frequency range and potential application in engineering. In this paper, a new mixed mode MR mount is proposed and an analytical model is established and used to predict the performance of MR mount. Meantime, a six degrees of freedom dynamic model of an in-line four-cylinder engine which has three points mounting system is derived by considering the dynamic behaviors of MR mount and its state space form is established. LQR and fuzzy-logic controllers are designed and synthesized to actively control the imposed vibration. The simulation results show that the proposed LQR or fuzzy-logic controllers can isolate the vibration of vehicle engine in a wide frequency range. The amplitudes can be suppressed well by employing this mount system. Its effectiveness will be verified via experiment in the second part of this work.

DFSS기법을 이용한 차량 엔진마운팅 시스템 최적화

DFSS기법을 이용한 차량 엔진마운팅 시스템 최적화

Optimisation of vehicle engine mount system using simulation-based design approach

The engine mount systems have a significant effect with respect to reducing the vehicle development time and cost regarding NVH characteristics and shortcomings not solved yet. There is still a need to enhance the performance of engine mount systems for vehicle ride comfort. This research presents a simulation-based approach to design optimised engine mount components to isolate the road- and engine-induced vibrations without the need for physical prototypes. Experimental tests are performed to define hyperelastic and viscoelastic models for non-linear finite element simulations of rubber components. After the correlation between the results of simulations and the product tests, a virtual engine mount model is presented to design optimum engine mount systems with the desired static and dynamic characteristics. The stiffness curves of different shapes of designs are investigated, and the best curve is chosen as an optimum design solution using the design of experiments approach.

Dynamic characterisation of elastomeric engine mounts of different geometry used in automotive industry: simulation approach

Generally, the vehicle engine mounting system consists of an engine as the vibration source and several mounts connected to the vehicle structure. The modern engine mounting systems have been successfully used to isolate the driver and passenger from both noise and vibration generated by the engine. However, there is still a need to improve the performance of engine mounting systems because of the requirements of vibration and noise level isolation for passenger cars and also because of the modern car designs that need lighter bodies and more power-intensive engines. Such a weight reduction and increased power requirements will often have adverse effects on vibratory behaviour that it will increase the vibration and noise level. This study is focusing on the current elastomeric engine mounts of different geometry and will also characterise the dynamic properties of elastomeric engine mount. This will be done by having parametric study of different engine mountings. The analysis of engine mounting rubber components should be accompanied by the vibration analysis of the engine mount system. This research opens up a passage to researchers to study and improve the elastomeric engine mount.

A literature review of automotive vehicle engine mounting systems

The ideal engine mount system should isolate engine vibration caused by engine disturbance force in engine speed range and prevent engine bounce from shock excitation. This implies that the dynamic stiffness and damping of the engine mount should be frequency- and amplitude-dependent. The development of engine mounting systems has mostly concentrated on improvement of frequency- and amplitude-dependent properties. The conventional elastomeric mounts do not meet all the requirements and can only offer a trade-off between static deflection and vibration isolation. Passive hydraulic mounts can provide a better performance than elastomeric mounts especially in the low frequency range. Semi-active techniques are usually used to further improve performance of hydraulic mounts by making them more tunable. The active engine mounting system can be very stiff at low frequency and be tuned to be very soft at the higher frequency range to isolate the vibration. The active engine mounts have been considered as the next generation of engine mounts. The optimization of engine mounting systems is quite desirable. The current work on the optimization of the engine mount systems shows some limitations.

Review of automotive vehicle engine mounting systems

The ideal engine mount system should isolate engine vibration caused by engine disturbance force in engine speed range and prevent engine bounce from shock excitation. This implies that the dynamic stiffness and damping of the engine mount should be frequency and amplitude dependent. The development of engine mounting systems has mostly concentrated on improvement of frequency and amplitude dependent properties. The conventional elastomeric mounts do not meet all the requirements and can only offer a trade-off between static deflection and vibration isolation, but there is still some room for improving the properties of elastomeric mounts. Passive hydraulic mounts can provide a better performance than elastomeric mounts especially in the low frequency range. Semi-active techniques are usually used to further improve performance of hydraulic mounts by making them more tunable. The active engine mounting system can be very stiff at low frequency and be tuned to be very soft at the higher frequency range to isolate the vibration. The active engine mounts have been considered as the next generation of engine mounts. The optimisation of the engine mounting system is quite useful both in terms of speed and more effective design. The current work on optimisation of the engine mount systems shows some limitation. Further work is needed to consider the nonlinear variations in properties of different types of mounting systems.