Simulation driven design of robust Crank-train systems for elevated In-cylinder combustion pressure

The need for increased in-cylinder pressure to meet the higher engine rating and stringent emissions norms requires special attention on the Main moving components torsional behaviour and the bearing performance. The work presented in this paper utilizes the 1D and 3D simulation potential of AVL EXCITE for the assessment of design changes required in Crank-Train system for the increased in-cylinder pressure from 170bar to 220bar. The key feature of the executed work was that all the design changes were accommodated with minimal changes in packaging / layout interfaces. The given work was executed on 6-Cylinder Turbocharged In-cylinder with Type V valve-train configurations. Initial brain storming & 0d calculation helped in understanding the design optimization required in each and every crank-train parts. Considering the guidelines available in terms of L/d ratio for the bearing, connecting rod length, the overall linkage specification was set up for starting with design work for inputs feeding in AVL EXCITE software and in-house developed excel sheets. With the user friendly simulation options available in AVL Excite, crankshaft geometry derived from stiffness matrix requirement to meet the torsional behaviour for the increased PFP was finalized. The work progressed considering the restrictions of the packaging layout along with no disruptions in the regular assembly line work flow process. Features like viscous damper, angle split connecting rod and improved PCJ flow for retention of Aluminium pistons were considered for implementation, a number of design iterations were done in crankshaft in terms of weight optimization .The simulation was done in an exhaustive manner which involved assessment of torsional behaviour results in terms of torsional frequency, angular acceleration, angular displacement at front and rear end for different orders, apart from this bearing assessment was done both in 1d and 3d domain considering the deformation of housing structures. The simulation work ended up in designing a cost effective robust design crank-train architecture for the given engine performance requirements