Importance

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Abstract

Systems and methods for skip fire spark ignition engine operation with a lean NOx trap after-treatment are provided. This system includes engine control circuitry capable of fueling and firing subsets of the engine's cylinders. Other cylinders are not provided fuel and are not fired (i.e. “skip fired”). The system includes an exhaust manifold for channeling the exhaust from at least some cylinders through a multistage catalytic converter. This may include a standard two-way or three-way catalytic converter. From the catalytic converter the exhaust may be channeled through a lean NOx trap. The lean NOx trap is able to chemically absorb the NOx emissions for regeneration according to a regeneration protocol. Lean NOx traps may include a substrate, an absorption material (also referred to as a ‘sorbent’) and a catalyst. The regeneration protocol may include monitoring NOx emissions downstream from the lean NOx trap, and comparing them against either a threshold or a lean NOx trap saturation model. Once the NOx emissions reach the threshold, or deviate from the model, a regeneration cycle may be performed.

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First Claim