Search Results

The noise and ride behavior of a vehicle can be significantly affected by vibrations transferred from the engine through the engine mounts to the chassis. Considering the engine, engine mounts, and chassis as individual components limits the potential gains on the overall vehicle performance. By describing the engine, engine mounts, and chassis as a vibrational system, emphasis can be placed on the capacity for engine mounts to improve the vibrational characteristics of a vehicle. The focus of this paper is on the role of engine mounts in the optimization process of vehicle vibrational and acoustic behavior. Passive, semi-active, and fully active engine mount designs are discussed. Characterization of the different effects of these types of mounts on noise and vibration performance is provided based upon analytical and experimental results.

A vehicle's structure vibration leads to perceivable accelerations at the steering wheel, the seat rails and the floor panels; additionally, these vibrations cause structure borne noise which contributes to the sound pressure level in the passenger's compartment. The perceivable structure accelerations and the sound pressure level constitute criteria for evaluating a vehicle's noise and vibration behavior. Consequently, improving the noise and vibration behavior is tantamount to reducing the vibration amplitudes of the vehicle structure. The operating engine causes engine mount forces which provoke the structure vibration. After the engine mount forces are calculated, the structure vibrations are simulated with a vehicle structure model described by transfer functions that relate the engine mount forces to the accelerations of all selected structure points where the vibration is supposed to be analyzed.