Design Concepts of Diesel Engines with Low Noise Emission

The sources of diesel engine noise and methods for its abatement are analysed and described. Typically, the overall engine noise is determined by the engine surface noise which, however, can hardly be reduced by more than 5 dB(A) with conventional noise abatement techniques. For reductions of 10 dB(A) or more, it is necessary to attenuate the noise of all external engine parts by a complete encasing of the engine. Various concepts for light weight acoustic engine casings which are closely fitted to the engine without acoustical lining or even integrated into the engine structure and which provide a 15 to 20 dB(A) noise reduction are demonstrated, including one concept for future light weight engines featuring a sound attenuating housing.