The Science of Engine Mounts and its Multidimensional Impact on Noise and Vibrations in Passenger Car

Abstract

<div class="section abstract"><div class="htmlview paragraph">A robust process of specifying engine mounting systems for internal combustion engines (ICE) has been established through decades of work and countless applications. Vehicle vibration is a critical consideration in the early stage of vehicle development. Apart from comfort, it also affects the overall vehicle's performance, reliability, Buzz-squeak and rattle (BSR), parts durability and robustness.</div><div class="htmlview paragraph">The most dynamic system in a vehicle is the powertrain, a source of vibration inputs to the vehicle over the frequency range. The mounting system supports a powertrain in a vehicle and isolates the vibration generated from the powertrain to the vehicle. In addition, it also controls the overall dynamic movement of the powertrain system when the vehicle is subjected to road load excitations and avoids contact between the powertrain and other adjacent components of the vehicle.</div><div class="htmlview paragraph">This paper investigates the effect of the mounting position, stiffness, and progressivity on overall vehicle-level vibrations. This study is constructed around a case of a front-engine passenger vehicle with a transverse mounting system to support the Gasoline powertrain unit. The baseline and optimum systems are studied digitally and then compared physically. It explains a traditional and new approach for optimizing the mounting system. Further, a methodology to optimize the vehicle vibration characteristics with the help of a new approach for mounting layout optimization is proposed. A case study with vehicle-level NVH measurement data for baseline and optimum systems demonstrates the strength of the new methodology and its multidimensional impact on overall vehicle-level NVH. The driver seat rail (DSR), Key on/off (KOKO), Tip in/Tip out (TITO) and Judder measurement results show the robustness of the proposed mounting system over its manufacturing variation of +/-10% dynamic stiffness.</div></div>