Search Results

For a spark-ignition engine, the parasitic loss suffered as a result of conventional throttling has long been recognised as a major reason for poor part-load fuel efficiency. While lean, stratified charge, operation addresses this issue, exhaust gas aftertreatment is more challenging compared with homogeneous operation and three-way catalyst after-treatment. This paper adopts a different approach: homogeneous charge direct injection (DI) operation with variable valve actuations which reduce throttling losses. In particular, low-lift and early inlet valve closing (EIVC) strategies are investigated. Results from a thermodynamic single cylinder engine are presented that quantify the effect of two low-lift camshafts and one standard high-lift camshaft operating EIVC strategies at four engine running conditions; both, two- and single-inlet valve operation were investigated. Tests were conducted for both port and DI fuelling, under stoichiometric conditions.

Reductions in fuel consumption, noise level, and pollutant emissions such as, Nitrogen Oxide (NOX) and Particulate Matter (PM), from direct-injection (DI) diesel engines are important issues in engine research. To achieve these reductions, many technologies such as high injection pressure, multiple injection, retarded injection timing, EGR, and high swirl ratio have been used in high-efficiency DI diesel engines in order to achieve combustion and emission control. However, each technology has its own advantages and disadvantages, and there is a very strong interaction between these methods when they are simultaneously used in the engine. This study presents a computational study of both the individual effect and their interactions of injection timing, EGR and swirl ratio separately and their interaction in a HSDI common rail diesel engine using the KIVA-3V code.