Investigation of LNT Regeneration Strategy for Diesel Engines with High Internal Residual Gas Rates

A diesel engine with a Lean NO_x Trap (LNT) operates alternating in lean and rich mode. In lean mode, the LNT stores the emitted nitrogen oxide emissions (NO_x). In rich mode, the engine produces large amounts of carbon monoxide (CO), hydrogen (H₂), and hydrocarbons (HC), which reduces the stored NO_x in the LNT. Law restricts NO_x, CO, and HC emissions. The aim is a low level of these emitters, but they can pass through the LNT. The right timing of lean and rich mode can help to reduce NO_x emissions with acceptable CO emissions. A variable valve lift system (VVT), which generates high internal residual gas rates, is considered to extend the operation range in which regeneration is possible. The present work deals with investigating regeneration-timing influences and developing an LNT regeneration strategy for real-driving-emission (RDE) simulation. Used this strategy, the VVT system’s potential is evaluated.