Hino's Advanced Low-Emission Technologies Developed to Meet Stringent Emissions Standards 2006-01-0275
Japan's new 2005 long-term emissions regulation was implemented in October 2005. Both NOx and PM emissions standards were reduced to 2 g/kWh and 0.027 g/kWh, which were 40 and 85 percent lower than the 2003 new short-term emissions standards, respectively. These emissions standards are as stringent as the Euro5 standards that are scheduled for implementation in 2008. In addition, the transient-cycle test procedure for emissions compliance, labeled JE05, was introduced to replace the D13-mode steady-state test procedure.
This paper describes exhaust emissions reduction technologies developed for Hino's 13-liter heavy-duty diesel engine so that it meets the above standards. A production catalyzed wall-flow DPF was employed to reduce PM emissions in both mass and small particles. NOx emissions were reduced by improving combustion with cooled EGR and without use of a NOx aftertreatment device. A NOx reduction catalyst was deemed premature for application in an engine operating under typical vehicle driving conditions in Japan because the exhaust gas temperature was low (e.g., 120 ∼ 200°C).
An EGR valve and VG turbocharger, both with infinitely adjustable functions, were employed to significantly reduce both smoke and NOx emissions. Positions of both the EGR valve and the variable nozzles of the VG turbocharger were controlled by using the feedback information of intake charge air flow rate and intake charge pressure to maximize the EGR rate and reduce NOx emissions while keeping smoke low, especially under transient operating conditions.