Method and system for exhaust aftertreatment

Abstract

Methods and systems are provided for reducing engine emissions using a branched exhaust system. In one example, a branched exhaust system may include a plurality of sub-branches each housing a distinct exhaust component, and an order of exhaust flow through each of the exhaust components may be adjusted based on engine operating conditions and temperature demand of the distinct components.

Description

technical field [0001] The present disclosure generally relates to methods and systems for controlling a vehicle engine to increase the efficiency of an exhaust aftertreatment system and reduce engine emissions. Background technique [0002] The engine may operate on an air charge provided via a turbocharger, with an intake compressor driven by an exhaust turbine. However, placing the turbo in the exhaust system can increase engine cold start emissions due to the turbo acting as a radiator. Specifically, engine exhaust heat during engine cold starts may be absorbed at the turbine, thereby reducing the amount of exhaust heat received at downstream exhaust aftertreatment devices. Thus, this delays reaching the light-off temperature at an exhaust catalyst such as a diesel oxidation catalyst (DOC) or a selective catalytic reduction (SCR) catalyst. Additionally, regeneration of particulate filters, such as DPFs, may be delayed. Placing the turbine downstream of the exhaust aft...

AI Technical Summary

Problems solved by technology

Further, positioning the DOC, DPF, and / or SCR catalyst upstream of the exhaust turbine can result in turbo lag and boost pressure loss during acceleration and during higher engine load conditions

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