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NVH refinement of passenger vehicle is essential to customer acceptance for premium or even mid-size segment passenger cars. Hydraulic engine mount is becoming common for these segments to reduce engine bounce, idle shake and noise transfer to passenger cabin. Modern layout of hydraulic mount with integrated engine-bracket and smaller size insulator has made it cost-effective to use due to reduction of cost gap from conventional elastomeric mounts. However the downsizing and complex internal structure may create some new types of noises in passenger cabin which are very difficult to identify in initial development stage. Main purpose of hydraulic mount is to provide high damping at low-frequency range (6~15 Hz) and to isolate noise transfer from combustion engine to passenger cabin within wide frequency range (15~600 Hz).This paper emphasizes on challenges and problems related to hydraulic mount development.

Quieter cabins are indispensable in today’s evolving automobile industry. The effective isolation of vehicle noise and vibrations are essential to achieve the above. Since, low frequency powertrain induced NVH has been one of the major contributors affecting noise and vibration levels inside the passenger cabin. Thus, use of hydraulic mounts is a natural choice for all major OEMs. The objective of this study is to optimize the design of the hydraulic mount de-coupler unit, to reduce the abnormal noise felt inside the cabin. This condition was observed when the vehicle was driven at 20~30 km/h over undulated road surface, found very often in Indian drive conditions. Due to lack of accuracy and repeatability errors during NVH data acquisition in actual driving condition, the above road profile was captured and subsequently simulated in an acoustically treated BSR (Buzz, Squeak and Rattle) four poster simulator.

Engine Shake is a low frequency phenomenon which causes vehicle vibration mainly in vertical direction leading to discomfort of the driver/passenger. This is caused by excitation due to small irregularities on smooth road surface. Engine mounting system design plays an important role in the Shake performance of the vehicle. This paper describes the Multi Body Dynamics (MBD) modeling and simulation study of the vehicle to analyze the Shake performance using Design of Experiments (DOE) approach. In the study, a 16 DOF configuration system model of the vehicle system is built using Multi Body Dynamic (MBD) simulation software ADAMS. The effect of change in Engine bush stiffness and damping on Floor displacement has been analyzed by carrying out DOE study using ADAMS. This is done to optimize the Engine bush parameters for improved Shake performance of the vehicle.