Detecting power imbalance in multi-cylinder inline diesel engine generator set

The main purpose of this paper is to develop the model of fuel injection adjustment for balancing the four stroke six cylinder inline diesel engine coupling generator set by detecting unbalance in operating engine by the frequency analysis of the crankshaft´s speed variation. In this work the crankshaft considered to be a rigid body, so that the variation of its angular speed could be directly correlated to the total gas-pressure torque. Actually, the variation of the crankshaft´s speed has a complex nature being influenced by the torsional stiffness of the cranks, the mass moments of inertia of the reciprocating and rotating masses and the average speed and load on the engine. Analyzing only the lower harmonic orders (¿, 1, and 1¿) of the speed variation spectrum can filter out the distortions produced by the dynamic response of the crankshaft. The information carried by these harmonic orders permits to establish correlations between measurements and the average gas pressure torque of the engine, and to detect unbalance and identify faulty cylinders. Detail experimental reading were taken on diesel engine coupling genset on the test bed of Greaves Cotton Ltd Pune, India.