Optimization of wheel suspension for NVH comfort English Free Members only

Due to the environmental concerns, the downsizing of the engines is the logical evolution of modern cars. Moreover, in order to keep a high level of performance, the high pressure turbochargers are used. The high gear ratio is a rule, which allows the driving at 1500 RPM, as usual engine speed. Due to the high cylinder pressure peaks, speed irregularities of the crankshaft and driveline torsional vibration amplitude increase as well as the resulting booming noise. The resulting torsional vibration becomes a major NVH issue for low RPM driving conditions.

Most of the torsional dynamic excitation is transferred by the lower arm of the front axle. Nevertheless, as a function of the suspension spring resonance frequency, the upper part of the front axle may become an important booming path too.

This paper addresses the physical phenomenon relative to the booming noise induced by the suspension spring. It underlines the importance of spring modal behaviour when NVH comfort in low RPM/high torque driving conditions is considered.