Method and Apparatus for Estimating a Dosing-Error in a Selective Catalytic Reduction System
AssigneePerkins Engines Company Limited
InventorsDavid Heaton, Michail Soumelidis, Bastian Maass, Thomas Steffen
Life of this patent
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Abstract
A method for determining if a selective catalytic reduction (SCR) device that is dosed with a reductant is being mis-dosed by considering an expected exhaust gas output state from the SCR device and measured exhaust gas output state, a NOx sensor sensitivity figure that is an indication of how sensitive the measured exhaust gas output state is to dosing errors and performing cross-correlation operations.
Claims20
A method for determining if a selective catalytic reduction (SCR) device that is dosed with a reductant is being mis-dosed, the method comprising the steps of:
- determining a first cross-correlation figure by cross-correlating a measured exhaust gas output state with a NOx sensor sensitivity figure, wherein the NOx sensor sensitivity figure is an indication of how sensitive the measured exhaust gas output state is to dosing errors;
- determining a second cross-correlation figure by cross-correlating an expected exhaust gas output state from the SCR device with the NOx sensor sensitivity figure;
- and
- determining a mis-dosing indication figure which indicates if the SCR device is being under-dosed, correctly dosed or over-dosed from the difference between the first cross-correlation figure and the second cross-correlation figure.
A method for determining if a selective catalytic reduction (SCR) device that is dosed with a reductant is being mis-dosed, the method comprising the steps of:
- determining a NOx readout difference figure from the difference between an expected exhaust gas output state from the SCR device and a measured exhaust gas output state from the SCR device;
- and
- determining a mis-dosing indication figure which indicates if the SCR device is being under-dosed, correctly dosed or over-dosed by cross-correlating the NOx readout difference with a NOx sensor sensitivity figure, wherein the NOx sensor sensitivity figure is an indication of how sensitive the measured exhaust gas output state is to dosing errors.
Dependencies are inferred from the claim text.