Closed loop temperature control in the SCR warm up mode to reduce emission variation

摘要

An exhaust aftertreatment system for a diesel engine includes a selective catalytic reduction (SCR) device and a diesel oxidation catalyst upstream of the SCR device. A method for warming-up the SCR device includes monitoring a plurality of combustion input parameters during an SCR warm-up strategy, monitoring a first temperature and a second temperature within the aftertreatment system, providing a feedback adjustment term as a function of a deviation in the first temperature from a desired temperature only when the monitored first and second temperatures are within a predetermined adjustment range, and initiating an adjusted SCR warm-up strategy based on the feedback adjustment term to converge the first temperature toward the desired temperature.

主权项

1. A method for warming-up a selective catalytic reduction (SCR) device in an exhaust aftertreatment system for a diesel engine, the aftertreatment system including a diesel oxidation catalyst upstream of the SCR device, the method comprising:
monitoring a plurality of combustion input parameters during an SCR warm-up strategy; monitoring a first temperature related to the temperature of the SCR device and a second temperature related to the temperature of the diesel oxidation catalyst within the aftertreatment system; providing a feedback adjustment term as a function of a deviation in the first temperature from a desired temperature only when both the monitored first and second temperatures are within a predetermined adjustment range, said predetermined adjustment range comprising a range of temperatures greater than a threshold temperature corresponding to a light-off diesel oxidation catalyst temperature at which the diesel oxidation catalyst operates at maximum efficiency and less than the desired temperature corresponding to a light-off SCR device temperature at which the SCR device operates at maximum efficiency; initiating an adjusted SCR warm-up strategy based on the feedback adjustment term to converge the first temperature toward the desired temperature; and operating the engine in accordance with the adjusted SCR warm-up strategy.