Integrated Exhaust Manifold Cylinder Head Design Methodology for RDE in Gasoline Engine application 2020-01-0169
In recent years, world-wide automotive manufacturers have been continuously working in the research of suitable technical solutions to meet upcoming stringent Real Driving Emission (RDE) and Corporate Average Fuel Economy (CAFÉ) targets, as set by international regulatory authorities. Many technologies have been already developed, or are currently under study by automotive manufacturer for gasoline engines, to meet legislated targets.
In-line with above objective, , Integrated Exhaust Manifold (IEM) is the key technology of the Internal Combustion (IC) engine to expand lambda 1 region expansion by reducing fuel enrichment at high load-high RPM by reducing exhaust gas temperature for RDE regulation. This technology also helps to increase fuel economy during cold start stage of World-wide harmonized Light vehicles Test Cycles (WLTC) by faster warm-up and High Speed fuel consumption by fuel enrichment reduction.
In this paper, explanation of design methodology is described for IEM individual cylinder exhaust ports layout strategies, seats, outlet area/position and water jacket structure. 3D Computational fluid dynamics (CFD) Simulations have been conducted for port flow optimization and water jacket-cylinder head structure thermal analyses for fatigue strength confirmation. Flow rate of individual cylinder exhaust ports was maximized by reducing pressure loss and cylinder to cylinder unbalance was minimized. 4 ~5% exhaust gas temperature reduction is attained to protect catalyst to meet RDE compliance. These items are achieved with design of experiments (DOE). IEM layout is done in current engine’s cylinder head envelope without making major modification in existing manufacturing line. In actual testing lambda region is expanded for full engine map with full wide open throttle (WOT) to meet requirements of WLTC targets without any enrichment.