Abstract
There are some NVH problems caused, or be thought to be caused, with drive line. However, drive line is a passive system in many cases. An engine or interaction in a powertrain is suspected as the cause of those problems. Gear rattle is common in manual transmissions and become uncomfortable noise when engine pulsation amplitude is larger than the threshold, depending on gear pair backlash and others, of the transmission. Torsional vibration of drive shafts is common in every vehicle. When the amplitude is larger enough, the driver or passengers complain longitudinal vibration caused by drive shafts. Possible triggers of the torsional vibration are engine toque rapid change (tip in & tip out), clutch engagement and nonlinear driving force transfer with torque converter immediate after starting from stand still. Mathematical models are derived for excitation source and transfer path to describe those NVH problems. NVH problem is alleviated when input force is shaped properly to avoid uncomfortable vibration or noise considering combined frequency property of excitation and transfer path in a power train system. Effectiveness of measures to reduce NVH problem is studied considering controllable range constraints of actual power plant.
