Possibilities to Reconstruct Indicator Diagrams by Analysis of the Angular Motion of the Crankshaft

The paper tries to establish the possible correlations between the fluctuations of the angular motion of the crankshaft -which may be easily measured-with the variations of the pressure time-histories in the engine's cylinders.

The model of the dynamic system of an engine shafting and the appropriate computing code are validated by comparison with measured angular motion of the front-end of the crankshaft. The algorithm of the code - based on the transfer matrix method - is then reversed in order to obtain the harmonic components of the exciting torques acting along the crankshaft from the harmonic components of the motion of the free-end of the crankshaft. Different ways of performing this task and the influence of nonuniform cylinder contributions are investigated and discussed.