Super Clean Electrified Diesel: Towards Real NOx Emissions below 35 mg/km

摘要

Air quality in the city centre is since decades one of the most important environmental topic for its big impact on the health consequences that it has for the citizens. In this context, the vehicles equipped with combustion engine are under criticism as one of the contributors to the deterioration of the air quality. As a consequence, a lot of discussions are taking place by the different city's administrations, worldwide, in order to implement legislative countermeasures to limit or completely ban the use of vehicle with combustion engines inside the city. In particular, the diesel engines as one of the strong contributors of NO_2 emissions are challenged by potential bans. Nevertheless the diesel keeps its benefit in terms of efficiency, representing a key technology in order to respect, in combination with diesel-like fuel (OME) produced by renewable sources or energy, the future target of CO_2 emissions reduction (-15% in 2025 and -30% in 2030 with respect to 2020 target). In this frame the Super Clean Electrified Diesel (SCED) program, launched by Continental in 2016 and arrived at the second step of development, is aimed to offer a technological platform that includes cost effective and integrated solutions to address the future post EU6d targets and the new stringent requirements proposed by NGOs (Non Gouvermental Organization) on the topic of real driving emissions. More in detail aim of the SCED demonstrator is to reach tail pipe NOx emissions level below the 35 mg/km in all real driving conditions. To this scope, focus of the program was the improvement of the exhaust gas treatment system in terms of hardware optimization and development of new control functions offered by the combination of new sensing strategies. This has been coupled with the further development of the 48 V system. In particular, it focusses the definition of control strategies aimed to properly manage the generator/motor phases of the electrical machine, keeping as targets the reduction of CO_2, the temperature increase of the exhaust gas treatment (through an electrified catalyst) and the state of charge of the vehicle battery, as requested by the upcoming legislation. This paper will describe the employment of technological bricks to upgrade a C-segment EU6b diesel vehicle in order to approach a potential "EU7" legislation scenario based on real NO_x emissions below 35 mg/km.