Method for adapting a lean NOx trap in an exhaust system of a motor vehicle
AssigneeFord Global Technologies, LLC
InventorYasser Mohamed sayed Yacoub
Life of this patent
Estimating the term…
Abstract
A method for adapting a lean NOx trap (LNT) in an exhaust system of a motor vehicle is provided. The method comprises if a difference between an estimated NOx concentration and a measured NOx concentration in exhaust downstream of the LNT is greater than a threshold, calculating an adaptation value, the estimated NOx concentration downstream of the LNT based on a kinetic model, and adapting the kinetic model, adjusting one or more operating parameters of the LNT, and indicating an aging state of the LNT based on the adaptation value. In this way, the model may be updated in real time to produce a robust prediction of LNT function.
Claims18
A method for adapting a lean NOx trap (LNT) in an exhaust system of a motor vehicle, comprising:
- executing instructions on a control system comprising a computer readable storage medium, the instructions including:
- if a difference between an estimated NOx concentration and a measured NOx concentration in exhaust downstream of the LNT is greater than a threshold, calculating an adaptation value, the estimated NOx concentration downstream of the LNT based on a kinetic model;
- adapting the kinetic model, adjusting one or more operating parameters of the LNT, and indicating an aging state of the LNT based on the adaptation value;
- and
- determining a storage adaptation rate of the LNT based on the adaptation value and exhaust mass flow, the storage adaptation rate utilized for a diagnosis of the LNT if a value of the storage adaptation rate is below a defined threshold and if LNT temperature is changing by less than a threshold temperature.
A vehicle system, comprising:
- an engine having an exhaust passage;
- a lean NOx trap (LNT) coupled to the exhaust passage;
- and
- a control system comprising a computer readable storage medium comprising instructions for:
- determining an estimated NOx concentration downstream of the LNT based on a kinetic model, the kinetic model based at least in part on an estimated NOx storage capacity of the LNT;
- comparing the estimated NOx concentration to a measured NOx concentration downstream of the LNT;
- if a difference between the estimated NOx concentration and the measured NOx concentration is greater than a threshold, calculating an adaptation value, the adaptation value corrected for LNT wall temperature and exhaust air-fuel ratio;
- and
- adapting the kinetic model and determining an aging state of the LNT based on the adaptation value.
A method for a lean NOx trap (LNT), comprising:
- executing instructions on a control system comprising a computer readable storage medium, the instructions including:
- determining a mass of stored NOx in the LNT based on a kinetic model, the kinetic model comprising a mass flow of exhaust through the LNT, an age of the LNT, energy balance in the LNT including heat losses and heat transfer, an amount of reductant in the exhaust, a storage capacity of the LNT, and an air-fuel ratio of the exhaust;
- determining an error value based on a concentration of NOx downstream of the LNT;
- adapting the kinetic model based on the error value;
- and
- adjusting the determined mass of stored NOx in the LNT based on the adapted kinetic model.
Dependencies are inferred from the claim text.