Search Results

Application of pre-mixed compression ignition (PCI) combustion for multi cylinder DI diesel engine has been reported in a previous paper [1]. On the FTP75 vehicle test cycle, application of the PCI combustion demonstrated a 50% decrease in the NOx level without any deterioration in fuel economy. In this study, PCI combustion properties were investigated under the condition of enhanced heat exchange capability of EGR cooler on multi cylinder DI diesel engine. Test results showed that the exhaust emissions and performance of PCI combustion were improved by increasing heat exchange on EGR cooler and PCI combustion region was expanded to higher load. However, few issues were encountered using higher heat exchange EGR cooler.

Control of NOx and PM from diesel engines is a key for enlarging its application in transportation field. To achieve this, many improvements have been done, for instance, the introduction of highly flexible common-rail injection system and cooled EGR system with advanced control strategy. In order to meet more stringent emission regulations in near future, research and development activities have been carried out energetically in the world. In this paper, a low emission combustion strategy is realized by combination of common-rail and cooled EGR. First of all, low soot combustion is approached by optimizing pilot and main injection, in which pilot is controlled to eliminate hot flame. Then, once low soot combustion achieved, higher EGR can be used to reduce NOx.

Tier 2 Emission standards enacted by the U.S. Environmental Protection Agency (EPA) require substantial emission reductions for new vehicles, including those with diesel engines. The standards are fuel neutral, and all light duty vehicles must eventually meet a fleet averaged emission level of Bin 5. To improve the emission capability for diesel engines, several advanced technologies have been investigated. These technologies include: common rail FIE with multi-injection capability, enhanced cooled EGR system with increased flow capability, variable geometry turbo charger, and a lower compression ratio piston. A new combustion approach using premixed diesel combustion was applied in the low load area for improving NOx and soot emissions significantly in the FTP-75 test cycle. Applying these technologies, engine out NOx was substantially reduced while maintaining similar soot levels.