Globally the customers are demanding more powerful yet silent vehicles to enhance their daily commuting and goods transportation needs. The current trend in the design is to enhance the engine power without major change in the physical configurations of the engine systems. Increasing the power and torque of the powertrain will have an undesirable and adverse effect on NVH levels.
In this research work, a light weight rear wheel drive vehicle was investigated from torsional vibration perspective. The vehicle is powered by a two cylinder engine with turbo charger. The power and torque of the vehicle was increased approximately two times with the help of turbocharger which resulted in increasing the powertrain torsional vibration. This increased vibration was further amplified through inevitable driveline resonances which causes severe vibration at the passenger seat location and steering. Also, the noise levels are above the comfortable zone.
Operational deflection shapes analysis and operational torsional vibration analysis was carried out on the driveline to identify the deflection shape and root cause for severe vibration. A dynamic torsional absorber used in the driveline has reduced torsional vibration to a great extent. The vibration levels are reduced by ∼50%. Also, the outcome of subjective jury conducted is that the noise levels are at completely acceptable level. The design and balancing specifications of torsional damper along the drive shaft is further enhanced to reduce the vibration levels and to sustain the durability criteria considering the real world usage pattern of the vehicle. Alternate methods like enhancing the suspension isolation, body stiffening and translational tuned mass damper are also investigated and their effect is analyzed.