Technical Paper
Investigations into the Excitation of Low Frequency Half Order Vibrations in a Diesel Passenger Car Powertrain
1993-05-01
931304
Recent progress in noise and vibration analysis technology had made great contributions to both noise level reduction and sound quality improvement in the interior noise of passenger cars. However, in spite of remarkable reductions in interior noise level, the sound quality in diesel passenger cars is still judged to be worse because of its different sound characteristics compared with gasoline versions. By using subjective testing, it was found that the main cause of poor sound quality in our test vehicle was the high contribution of relatively low frequency half-order multiple components, principally 2.5 and 3.5 order of engine rotation. The undesirable vibration transfer characteristics of the chassis was found to be one cause, but the half order components of powertrain vibration were also shown to be at a high level, and were the source of the excitation.
