Reduction of Noise Emissions from Diesel Engine Surfaces

One of the effects of the existing and proposed European legislation limiting vehicle noise has been to generate a requirement for quieter engines. A simple analysis of the vibration of the external surfaces of several in-line engine structures has shown how the noise from the engine surfaces can be reduced, provided that all the thin-section areas of the external surface are treated.

Noise-reduction techniques have been evolved for all the commonly used surface structures for diesel engines, and these are described in this paper. Four in-line diesel engines have been treated by these techniques, and noise reductions of 5-8 dBA have been obtained. In all cases, the same manufacturing plant was used to machine the modified crankcase/cylinder block casting; the valve gear cover and sump were modified versions of those already fitted to the engine.