Study the Effect of Torsional Vibration on Valvetrain Dynamic in a Heavy Duty Diesel Engine Using Multi-Body Dynamic

Today, due to technical, commercial and environmental requirements, internal combustion engines especially heavy duty diesel engines must operate with high cylinder pressures and the components must be optimized for the best performance. Heavy duty diesel engines usually rotate the driven machinery with a large inertia such as generators, or ship propeller. A crankshaft is subjected to periodic dynamic loads; also other inconsistencies could make misfire in engine and because of the torsional vibration in engine, the crankshaft has fluctuating instantaneous speed. Due to the essence of this type of the engine which has heavy parts, beside the robust design of them, and relatively high torques which need to rotate the camshaft, these engines valvetrain normally drive with gears. In consequence the rotating speed of engine crankshaft completely transfer to the camshaft because of high amount of crank train’s inertia in comparison with the valve train and in some cases using the damper for camshaft is required. Modern calculation methods allow for the precise determination of system dynamic and loads. Thus, it is possible to consider design margins that ensure sufficient reliability to avoid undesired dynamic behavior which could lead to structural failures, besides avoiding the components over sizing. In this paper ADAMS\Engine commercial software has been used for simulating the coupled engine cranktrain and valve train subsystems of an engine under development. The engine complete dynamic simulation with Multi-Body Dynamic tool including backlash in gear train and torsionally flexible camshaft, prepare a good model for study the effect of engine cranktrain dynamics on its valvetrain.