%0 Journal Article
%T Improving diesel engine efficiency at high speeds and loads through improved breathing via delayed intake valve closure timing
%A Cody M Allen
%A Gregory M Shaver
%A James McCarthy
%A Kalen R Vos
%A Lisa Farrell
%A Xueting Lu
%J International Journal of Engine Research
%@ 2041-3149
%D 2019
%R 10.1177/1468087417743157
%X Valve train flexibility enables optimization of the cylinder-manifold gas exchange process across an engine¡¯s torque/speed operating space. This study focuses on the diesel engine fuel economy improvements possible through delayed intake valve closure timing as a means to improve volumetric efficiency at elevated engine speeds via dynamic charging. It is experimentally and analytically demonstrated that intake valve modulation can be employed at high-speed (2200£¿r/min) and medium-to-high load conditions (12.7 and 7.6£¿bar brake mean effective pressure) to increase volumetric efficiency. The resulting increase in inducted charge enables higher exhaust gas recirculation fractions without penalizing the air-to-fuel ratio. Higher exhaust gas recirculation fractions allow efficiency improving injection advances without sacrificing NOx. Fuel savings of 1.2% and 1.9% are experimentally demonstrated at 2200£¿r/min for 12.7 and 7.6£¿bar brake mean effective pressure operating conditions via this combined strategy of delayed intake valve closure, higher exhaust gas recirculation fractions, and earlier injections
%K Variable valve actuation
%K intake valve modulation
%K dynamic charging
%K volumetric efficiency
%K fuel economy
%U https://journals.sagepub.com/doi/full/10.1177/1468087417743157