Identification of Mechanical Sources of Noise in a Diesel Engine: Sound Originating from Piston Slap

Abstract

The sound produced by the piston slap of a diesel engine is investigated by standard methods of sound and vibration analysis augmented by correlation of incidence of individual transient components. This latter technique makes use of information obtained from the tuned outputs of the noise signal, focusing attention on the incidence of single-frequency transients. The contribution of piston slap to the overall noise emitted by an engine is studied analytically by examining equations for the transverse motion of the piston and experimentally by varying engine parameters such as piston-cylinder clearance, gudgeon-pin offset, and piston lubrication. By considering the various distinct characteristics, an insight is gained into the mechanism of noise generation and radiation.