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BEVs and FCEVs are getting more popular since they can contribute to reduce the concern of global warming and the environmental pollution, especially in urban area, they do not emit exhaust gas emissions. In other words, the expectation of a Zero emission society increases. On the other hand, HEVs and PHEVs which have internal combustion engines have realized a drastic reduction of fuel consumption and exhaust gas emissions thanks to optimal power management of the motor and the engine. They already achieved a great contribution toward CO2 reduction in global level. In order to realize emission free society, this research addresses “Zero-Emissions challenge” of PHEV exhaust gas emissions (to be able to consider equal to BEV in well to wheel), contributing to the global environment pursuing new value for the internal combustion engine.

In this paper, a control strategy to switch NSR (NOx storage and reduction) function from standard DeNOx by rich combustion to DiAir (Diesel NOx After-treatment by Adsorbed Intermediate Reductants) and additional advantages to use HCI (Hydrocarbon Injector) during desulfation were introduced. Investigations under a transient cycle suggest that NOx conversion with DiAir is strongly affected by preliminary NOx storage condition in the NSR catalyst. To avoid NOx breakthrough just after starting HC dosing for DiAir, a rich operation to reduce stored NOx was shown to be important and high NOx conversion could be maintained using this control strategy under a transient cycle. Furthermore, by combining HCI and in-cylinder post injection, usage of rich condition for NSR DeSOx can be expand to wider engine speed and load area.

An unprecedented phenomenon that achieves high NOx conversion was found over an NSR catalyst. This phenomenon occurs when continuous short cycle injections of hydrocarbons (HCs) are supplied at a predetermined concentration in lean conditions. Furthermore, this phenomenon has a wider range of applicability for different catalyst temperatures (up to 800 degrees Celsius) and SVs, and for extending thermal and sulfur durability than a conventional NOx storage and reduction system. This paper analyzes the reaction mechanism and concludes it to be highly active HC-deNOx by intermediates generated from adsorbed NOx over the base catalysts and HCs partially oxidized by oscillated HC injection. Subsequently, a high performance deNOx system named Di-Air (diesel NOx aftertreatment by adsorbed intermediate reductants) was demonstrated that applies this concept to high speed driving cycles.