Methods and systems for ammonia slip detection
AssigneeFord Global Technologies, LLC
InventorsChris Riffle, Frank M. Korpics, Michiel J. Van Nieuwstadt, Devesh Upadhyay, John Paul Bogema, Jeff Reich
Life of this patent
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Abstract
Various systems and methods are described for detecting ammonia slip. In one example method, an amount of exhaust gas recirculation is reduced when output from an exhaust gas sensor indicates an increase in nitrogen oxide above a threshold amount. When the sensor output increases above a second threshold while the exhaust gas recirculation is reduced, the sensor output is allocated to nitrogen oxide; and when the sensor output does not increase above a second threshold while the exhaust gas recirculation is reduced, the sensor output is allocated to ammonia.
Claims19
A method, comprising:
- responsive to a threshold increase in nitrogen oxide indicated by an exhaust gas sensor, disabling exhaust gas recirculation (EGR) while repeatedly injecting urea at least more than twice, an amount of urea in each injection maintained while EGR is disabled;
- while an amount of exhaust gas recirculation is reduced, allocating output from the sensor to each of ammonia and nitrogen oxide and in different amounts depending on a change in sensor output;
- and
- adjusting one or more operating parameters based on the allocation and the change in sensor output.
A method, comprising:
- responsive to a first threshold increase in nitrogen oxide indicated by an exhaust gas sensor, reducing an amount of exhaust gas recirculation while repeatedly injecting an amount of urea;
- while the amount of exhaust gas recirculation is reduced:
- allocating sensor output to ammonia when the sensor output changes by less than a second threshold amount;
- and
- allocating sensor output to nitrogen oxide and indicating a reduced efficiency of a selective catalytic reduction catalyst disposed upstream of the sensor when the sensor output increases by greater than the second threshold amount;
- and
- adjusting one or more operating parameters based on the allocation and the sensor output.
A system, comprising:
- an engine with an exhaust system;
- an exhaust gas recirculation system coupled between the engine and the exhaust system:
- an exhaust treatment system disposed in the exhaust system and including a selective catalytic reduction catalyst, a urea injector disposed upstream of the catalyst, and an exhaust gas sensor disposed downstream of the catalyst;
- and
- a control system in communication with the sensor, the control system including non-transitory instructions to turn off exhaust gas recirculation while repeatedly injecting urea, at least more than twice, with a maintained amount of urea injection responsive to sensor output exceeding a threshold amount of nitrogen oxide, and, while exhaust gas recirculation is turned off, allocating output from the sensor to each of ammonia and nitrogen oxide and in different amounts depending on a change in sensor output, and adjusting one or more operating parameters based on the allocation and the change in sensor output.
Dependencies are inferred from the claim text.