A Review of Parameters Affecting the Noise and Vibration in Diesel Powered Passenger Cars

The noise and vibration properties of diesel engines call for increased efforts in manufacturing passenger cars to achieve a level of comfort comparable to gasoline cars.

Severe problems arise at low engine speed when high compression forces give rise to vehicle body vibrations. Together with the vibration behavior at mid and high engine speed this fact demands a careful selection of engine mount position and mount properties. This selection must be made with respect to both the engine vibration excitation and to the vibration response of the vehicle body.

Noise within the vehicle is influenced by the transfer of vibration energy from the engine into the vehicle structure and its radiation into air, as well as by the noise characteristics of the engine and the sound transmission properties of the vehicle cabin. Starting from measurements of vehicle interior noise it is the aim of this paper to define reasonable limits of diesel engine noise and vibration levels on the one side and of sound and vibration transmission properties on the other side.

For this purpose vibration and noise has been studied in different vehicles, the influence of a modified suspension system on interior noise is demonstrated and limits of acoustic treatment of the firewall are presented.