Research of coordinated deformation characteristics for diesel engine main bearing based on bearing clearance margin

Abstract

A method for characterizing coordinated deformation of diesel engine main bearing is proposed to address the problem that traditional evaluation indexes are difficult to accurately characterize the coordinated deformations of the main bearing shell and the crankshaft. The margin between the main bearing clearance and the assembly clearance is employed to judge whether motion interference occurs between the main bearing shell and the crankshaft journal after deformation. The numerical calculation method for the main bearing clearance is proposed. Experiments are designed and conducted to verify the feasibility and accuracy of the evaluation index. The influencing mechanisms of sensitive parameters on the coordinated deformation characteristics of the main bearing are explored based on the orthogonal test. The results show that it is feasible to take the main bearing clearance as the evaluation index of the coordinated deformation. The relative errors between the calculation results and the measurement data of the centripetal radial deformation of the main bearing shell in the preload condition and the main bearing loading condition are less than 7% and 9.7%, respectively, indicating the accuracy of the computational method. The main bearing clearances tend to decrease with the increase of horizontal and vertical bolt loads until they remain basically constant. The main bearing clearance decreases with the increase of the interference followed by a slight increase, while it is positively correlated with the side clearance. This study provides theoretical basis for main bearing stiffness reliable design of HPD diesel engine.