Dynamic effects of the power-conversion module in a reciprocating engine

Abstract

The forced response characteristics of piston, connecting rod and their assembly, henceforth called power-conversion module, is studied subjecting a forced response model of such a module to combustion characteristics in order to investigate clattering noise characteristics brought with compression ignition excitation. Existing research either focused on the piston or the connecting rod solely. As demonstrated by the modal analysis of the whole power-conversion module, it is revealed that the natural frequencies of the entire module dominate the noise-characteristics of clattering noise even when using a linear model. A subsequent parametric study applying different combustion characteristics with different pressure rise rates, but similar peak pressures on the modal-model of the power-conversion module delivered novel insights into the root cause of clattering noise characteristics. Moreover, the approach delivers an amended understanding of disturbing noises occurring in knock control systems of internal combustion engines. The reason for empirically elaborated limits of the maximum cylinder pressure rise rate to achieve smooth engine acoustics, published first in the late 1920s, was revealed.