Temperature Impact on Modeling and Control of Lean NOx Trap

Gasoline Direct Injection (GDI) engine has a significant fuel economy improvement over the traditional port fuel injection engine. The tradeoff for this benefit is excessive exhaust emissions, especially NOx. Three-way-catalyst (TWC) is inefficient to treat NOx emission during lean operation. So Lean NOx Trap (LNT) is invented for NOx aftertreatment and it has both storage mode and purge mode. Research on modeling and control of LNT has been conducted, but it is still lack of the essential information on the temperature effect. This research focuses on the impact of trap temperature on LNT storage time, purge time and fuel economy. The mechanism of temperature effect on LNT is investigated at first. Then the temperature control strategy based on fuel economy improvement is proposed.