In order to allow continued production of the AM General Optimizer 6500 during MY 2007 through 2010 this IDI engine (Indirect Injection - swirl chamber) requires sophisticated aftertreatment controls while maintaining its fuel economy and durability.
The main purpose of the development program was to retain the relatively inexpensive and simple base engine with distributor pump and waste-gated turbocharger, while adding hardware and software components that allow achievement of the phase-in emission standards for 2007 through 2010. The aftertreatment system consists of Diesel Oxidation Catalyst (DOC), NOx Adsorber Catalyst (or DeNOx Trap - DNT) and Diesel Particle Filter (DPF). In addition to the base hardware, an intake air throttle valve and an in-exhaust fuel injector were installed.
The presented work will document the development process for a 2004 certified 6.5 l IDI heavy-duty diesel engine to comply with the 2007 heavy-duty emission standards. The system architecture evaluation proved to be one of the key development items that determined the packaging in the projected vehicle platform. Based on the temperature profile, it was found that the DOC-DPF-DNT configuration is mandatory to achieve NOx and NMHC standards. The development of the DPF regeneration, deNOx and deSOx strategy were strongly based on a multi-variable controls approach using temperature or lambda interventions depending on the system request.
Development results for the HD-FTP and SET (13-mode Supplemental Emissions Test) show that the tailpipe emissions and the NTE (not-to-exceed) limits can be met with a considerable safety margin allowing reasonable degradation factors.
The integrated system was installed in a project vehicle and underwent multiple climate testing trips focusing on DPF regeneration under cold ambient, high altitude and hot ambient conditions.
It could be proven that a concept with a comparably cost-effective base engine which does not utilize direct fuel injection, along with an advanced aftertreatment control system, is capable to meet the U.S. 2007-2010 phase-in emission standards.