Detailed Analysis of CG Variation Effect on Connecting Rod Design of a Turbocharged Diesel Engine

The conventional methods of connecting rod design consider the centre of gravity (CG) position at 2/3rd distance from connecting rod small end. The connecting rod CG position decides the reciprocating and rotating mass distribution. The reciprocating force impacts inertia stresses at the connecting rod small end while rotating force impacts the inertial stresses, minimum oil film thickness (MOFT) and peak oil film pressure (POFP) at the connecting rod big end. This paper work has analyzed connecting rod design in view of three probable causes of CG position variation as due to dimensional changes to sustain higher loading, manufacturing process variation and high speed of turbocharged (TC) engine. Total nine load cases have been considered for study of these causes. As well, CG variation impact is analyzed at big end bearings for MOFT and POFP. This study helped to optimize the CG position during connecting rod redesign while upgrading the engine aspiration from naturally aspirated (NA) to Turbocharged engine which has resulted in 50% increase in the load on the connecting rod. The redesigned connecting rod is validated by experimental method. This study has given insights about the positioning of the CG location during the connecting rod design.