An Analysis of the Movement of the Crankshaft Journals during Engine Firing

In order to clarify the generation mechanism of engine noise, which is a significant problem in the fast-burn engine, the behavior of the crankshaft, the force transferred to the main bearing caps supporting the crankshaft, and the deformation of the cylinder block were analyzed during engine firing.

As a result, it was determined that the crankshaft which deflects due to inertial force pushes the bearings violently under combustion pressure and causes intense fore-and-aft vibration of the bearings, which in turn causes vibration of the cylinder-block skirt. This is a main cause of combustion noise.