Abstract:
To help meet exhaust gas emissions standards, an internal combustion engine may have an exhaust gas aftertreatment device located in its exhaust gas stream. However, the exhaust gas aftertreatment device may only operate effectively above a minimum threshold temperature. In the present disclosure there is provided a method and apparatus for warming the exhaust gas aftertreatment device and a method and apparatus for controlling when exhaust gas aftertreatment device warming should be initiated and stopped.
Abstract:
The present disclosure provides a method and apparatus for estimating the amount of ammonia output from an SCR device by determining a NOx conversion efficiency of the SCR device using a variance of a NOx input measurement and a variance of a NOx output measurement, obtaining an estimate of NOx output from the SCR device using the NOx conversion efficiency and using that estimate to determine an estimate of ammonia output from the SCR device.