The objective of this research is to reduce the half order noise in a hybrid vehicle at idle speed charging condition. The measurements including vehicle interior noise and cylinder pressure of engine were introduced in order to find the correlation of ignition of different cylinders and frequency half order noise. The modal analysis and frequency response was conducted to identify the natural frequency of crankshaft and powertrain. The modelling and simulation of powertrain based on multi body dynamic method was used to understand and optimize half under noise. The bending vibration of torsional vibration damper of crankshaft and dual mass flywheel, the bearing load and powertrain mount vibration were then analysed. The weight of torsional vibration damper and dual mass flywheel, the diameter of crank pin and structure of dual mass flywheel are shown to affect the powertrain vibration which leads to the structure-borne noise. From this study, it is concluded that the optimization of crankshaft system can improve the powertrain vibration. The optimization concerns on load transfer path also can lead to vibration refinement. Finally, the interior noise of vehicle with optimized parts was tested and showed good noise behaviour. The half order noise issue is solved and give a comfortable sound to customer.

Hybrid powertrain; Half order noise; Crankshaft; Bending vibration