Effects of Bearing Steps on Probable Wear Damage of Main Bearings of an IC Engine

Abstract

When two bearing shells are assembled in the bearing housing, it is possible that the edges of the two shells do not fit in the radial direction completely and have an offset relative to each other. This assembly error, which can have different causes, is called the bearing step in this paper. The bearing step can lead to wear damage in bearings. The effects of bearing step on the lubrication performance of main bearings and the probable wear damage have been investigated. To calculate the bearing lubrication characteristics such as maximum oil film pressure and minimum oil film thickness, elasto-hydrodynamic model, which includes the mass conservation algorithm, has been applied. The objective of this work is to investigate the effects of bearing steps on the lubrication performance of the main bearings and assess the probable wear damage of main bearings due to bearing step. The prediction of elasto-hydrodynamic model is very proximate to what really happened. The results show that for the under-study 12-cyl engine, main bearing No. 2 involved with medium wear damage. Wear damage in this main bearing No. 3 is not a concern, while main bearing No.4, 5 and 6 do not predict the probability of wear damage. For main bearing No.7, it is concluded that considering step and bore relief in simulation has high importance so that the solution without step and bore relief does not predict the wear, but with step and bore relief predicts medium wear damage.