Requirements of External EGR Systems for Dual Cam Phaser Turbo GDI Engines

Abstract

<div class="section abstract"><div class="htmlview paragraph">It has been clearly demonstrated separately, that the application of both Dual Cam Phasers (DCP) and External Cooled EGR systems are highly beneficial to improving the efficiency of highly-boosted GDI engines. DCP systems can optimize the volumetric efficiency at WOT conditions, improve boost and transient response at low engine speeds, and provide internal EGR at low RPM part-load conditions. External cooled EGR has been demonstrated to dramatically improve the fuel consumption, lower turbine inlet temperature, and improve emissions at high power conditions.</div> <div class="htmlview paragraph">In previous investigations by the BorgWarner Engine Systems Group, we showed that full engine speed/load range EGR coverage can be obtained by combining High Pressure Loop and Low Pressure Loop external EGR systems with a DCP strategy.</div> <div class="htmlview paragraph">In this report we will present further studies of the factors that provide a strategy for mixing LPL and HPL in the region of the engine map where the engine has sufficient delta-P across the systems to flow both loops without additional throttle of backpressure devices.</div> <div class="htmlview paragraph">Additionally, we present the benefits of pre-close-coupled catalyst source for the LPL EGR system.</div></div>