Control of Charge Dilution in Turbocharged CIDI Engines via Exhaust Valve Timing
نویسندگان
چکیده
ABSTRACT Stringent NOx and particulate emission constraints require high levels of exhaust gas recirculation. In this paper we model and analyze a Variable Valve Timing methodology that in steady-state achieves large levels of internal Exhaust Gas Recirculation (iEGR) or residual charge in Compression Ignition Direct Injection (CIDI) engines. Current external Exhaust Gas Recirculation (eEGR) techniques rely on a positive pressure drop between the exhaust and the intake manifold, thus compromising fuel economy by degrading turbocharger and engine matching. In contrast, internal exhaust gas recirculation through early exhaust valve closing allows better control of residual charge with potential benefits in turbolag reduction.
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