Evaluation of crank mounted fan for TV and crankshaft first journal bearing MOFT analysis for 3.8 L 4 cyl. diesel water cooled engine

Abstract

Engine crankshaft used to validate for Torsional Vibrations by limiting the amplitude within the safe working design limit. The same is radially measured with non-contact optical laser sensor equipment mounted on Crankshaft front end. With the test bed measured Peak firing Pressure Vs Crank angle data, crank train has been modelled in AVL EXCITE. The model is then calibrated for TV and MOFT measured on actual engine. To this, a fan model has been added and results were derived for TV and MOFT with crankshaft mounted rigid fan and Viscous drive Fan. The bearing life is predicted considering extra bending load due to fan's weight. The effect of this extra load on the First journal bearing oil film thickness is derived by adding equivalent gas pressure on the crankshaft and thereby predicting the bearing life. This paper addresses the effect on Torsional Vibration Characteristics and Minimum Oil Film Thickness by applying viscous fan and mounting of Fan on Crankshaft as opposed to that on Water Pump for 3.8 L 4 cyl. 140 HP Engine. © 2013 Springer-Verlag Berlin Heidelberg.