Transient in cab noise investigation on a light duty diesel passenger vehicle.

Abstract

A diesel engine in cab sound quality for passenger car market is scrutinized more closely than in the mid- to heavy duty diesel truck applications. This is obviously due to the increasing expectations from the customers for gasolinelike sound quality. This paper deals with a sound quality issue recently investigated on a light duty diesel engine for a passenger van application. The objectionable noise complaint occurred during the vehicle transient operating conditions and was found to be caused by the change in the pilot quantity over a very short period of time. The root cause of the noise complaint was investigated on the noise complaint vehicle as well as simultaneously on a standalone engine in the noise test cell. Several critical combustion and performance parameters were recorded for diagnosing the issue. In addition, various standard sound quality metrics were employed to differentiate the sound quality of the objectionable noise. The issue was resolved and verified by making appropriate changes to the engine calibration without affecting key requirements such as emissions and fuel economy. Finally, the findings from the experimental tests are summarized and appropriate conclusions are drawn with respect to understanding, characterizing, and resolving this transient, combustion related impulsive powertrain interior noise issue.