R Rohani - Engine Testing Laboratory, Irankhodro Powertrain Company

One of the most important challenges in engine test beds is the selection of suitable coupling. The coupling is supposed to connect the engine and dynamometer together with a reliable and safe operation. So that this professional field calls for the adequate technical know-how of reciprocating engines and the engine test beds working conditions. In a more detailed case, testing a 3-cylinder engine in an engine test bed is certainly a tricky issue required a special care. Torsional vibration in 3-cylinder engines would be very challenging where vibration-reducing systems like dual mass flywheels (DMF) or balancing shaft gears are employed. Despite the advantages of a dual mass flywheel in the vehicle, testing an engine with dual-mass flywheel is a complicated subject. In this paper, the practical countermeasures for torsional vibration attenuation in testing a 3-cylinder IC engine are proposed to prevent any unpredictable failure of components of driveline. The behavior of a DMF in the static mode is studied to decide on the application of such a system in engine testing driveline. The critical speed of driveline connecting a three cylinder engine to an AC dynamometer as well as an eddy current dynamometer is then calculated for a broad range of driveline torsional stiffness. It is also shown that driveline critical speed considerably varies with increasing the engine mass moment of inertia. Finally, the driveline is arranged in a way that provides a safe operation with minimum vibration.

driveline, 3-cylinder engine, coupling, torsional vibration