Use of a New Formula in the Analysis of Torsional Harmonic Excitations for IC Engines

This paper gives a new theoretical formula which relates torsional harmonic coefficients due to gas pressure and mean indicated pressure (MIP) in a cylinder for a four-cycle internal-combustion engine. A practical example in a diesel engine hits been illustrated to verify its accuracy and utility. Based on the discovered formula, some characteristics of harmonic excitations and their relations with NIP are discussed. It is shown that the formula can be used to analyze the relationships between all harmonic coefficients and MIP, and to determine their values in the analysis of torsional vibrations.