Gas Exchange Optimization and the Impact on Emission Reduction for HSDI Diesel Engines 2009-01-0653

The main tasks for all future powertrain developments are: regulated emissions, CO2-values, comfort, good drivability, high reliability and affordable costs.

One widely discussed approach for fuel consumption improvement within passenger car applications, is to incorporate the downsizing effect. To attain constant engine performance an increase of boost pressure and/or rated speed is mandatory. In both cases, the mass flow rate through the intake and exhaust ports and valves will rise. In this context, the impact of the port layout on the system has to be reassessed.

In this paper, the impact of the port layout on a modern diesel combustion system will be discussed and a promising concept shall be described in detail. The investigations shown include flow measurements, PIV measurements of intake flow, CFD simulations of the flow field during intake and results from the thermodynamic test bench. One of the important topics is to prove the impact of the flow quality on the combustion.

Based on these investigations, a new port concept shall be presented, which uses a variable valve lift to provide a highly variable swirl, a homogenous flow field in the cylinder and excellent flow coefficients, in order to increase the volumetric efficiency in combination with reduced flow losses.