New Methods of Evaluating and Improving Piston Related Noise in Internal Combustion Engines

Reducing piston related noise in internal combustion engines is generally not a question of meeting legislatory limits but more often related to customer annoyance and subjective complaints. In the daily work of the component development engineer audible noise in the vehicle often is the first and most important guideline for component optimisation. The paper deals with improving several piston related noise types using vibration analysis, measurement of piston secondary motion, subjective noise assessment methods based on artificial head noise recording techniques and the calculation of noise excitation using a state of the art computer model with consideration of piston elasticity. All methods are combined to solve the NVH problems in a joint effort. The paper describes the mechanism of excitation, perceived noise emission and its relation to cylinder block vibration. It also demonstrates the correct piston layout for minimum noise.

Engines are modern gasoline engines as well as turbo-charged highly loaded passenger car Diesel engines.