Engineering and Technology Journal,
2008, Volume 26, Issue 3, Pages 62-80
AbstractThis research summarized the possibility of prediction of the cylinder
pressure (combustion pressure) of internal combustion engine by measuring the
vibration amplitude at the housing of the main bearing of crankshaft.
A mathematical model was developed using the Transfer Matrix Method to
analyze the crankshaft vibration. The journal bearings were modeled as springs
and dampers in the direction of main system coordinates. The bearings were
under dynamic load conditions. This was achieved by sampling the crankshaft to
multi-supported beam using the Equation of Three Moments Theory. A relation
between the reactions were found at main bearings and the applied forces on the
crankshaft as a result of pressure and the effect of both reciprocating and
rotating motion .
A computer program in Fortran language was developed for each cited
The study depends on experimental results previously measured on (Zetor MType),
four stroke, 4-cylinders diesel engine under motoring condition using
special prepared computer program. The resulting amplitude of vibration at local
position were compared with the experimental amplitude also the cylinder
pressure were corrected until a convergence criterion is reached between the
theoretical and the experimental amplitudes. The instantaneous cylinder pressure
will be predicted, two samples of data were taken for the amplitude of vibration
at two rotational speeds.
The results show good agreement with those obtained experimentally. Also
the rotational speed was deduced by the use of practical measurement of
vibration amplitude and cylinder pressure for two rotational speeds using the
same program with simple change and showed good agreement between
practical and theoretical results.
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