MOTION TRAJECTORIES OF A CRANKSHAFT IN HYDRODYNAMIC JOURNAL BEARING

Abstract

It Is no doubt that the Internal combustion engine Is one of the. important prime movers to date. With a wide range of application in various environments, and with advancement in technology, the requirements from the I.C. engine have a trend towards higher speeds. and higher specific output. The crankshaft of the Internal Co combustion engine can be said be the heart of the mechanism which converts the reciprocating motion to rotary motion as it is subjected to very complex loading. Also the journal bearings in which the crankshaft is supported allow relative motion and transmit the load to the engine structure. Since the crankshaft is subjected to time varying forces, the performance of the journal bearings has a great Impact on the overall performance of an engine. The .crankshaft. bearings must be capable of generating adequate film pressure in order to maintain a consistent. thickness of the fluid film, so as to prevent metal to metal contact., wear etc.. The journal bearing performance Is affected by all these factors. One way of assessing the performance of the. journal bearing Is to obtain the .journal centre locus within the bearing clearance. An attempt, therefore, has been made to obtain the main journal locus. In the present study, the crankshaft has been treated as a structural member in three dimension and using Finite Element technique, the main bearing forces are obtained. The hydrodynamic journal bearing has been analyzed using short bearing approximation. Using Euler predictor-corrector iterative processes, the journal centre position is obtained for all time steps. The Euler Cauchy method has also been used for determining the locus and it has been observed that the. Euler - Cauchy method gives more accurate results than. the Euler predictor - corrector method