| Popis: |
This paper examines the influence of future boundary conditions for boosting systems. It employs engine process simulation to select different intake valve timings on a four-cylinder 1.4-l spark-ignition engine with a view to illustrating the extent to which a single-stage boosting system is capable of providing the level of boost pressure that is demanded. Single-stage boosting systems show a number of benefits over two-stage systems in terms of cost, package and catalyst light-off. This was the reason for examining how far adapting or advancing a single-stage boosting system can meet the rising demands on boost pressure. Variabilities on the compressor and turbine side were used to increase boosting system spread. Comprising VTG, wastegate and VTC, the most promising configuration makes it possible to attain the basic full-load curve using Miller timings (ΔIVC = 40°). This reduces consumption in the region of 3 to 6%. Despite demanding a higher level of boost pressure, the supercharging system provides even further potential for increasing mean effective pressure by 10% at same low end torque speed. Measurements on a single-cylinder engine were able to confirm the fuel-saving trends identified in simulation. |
