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US 8,893,475 B2Granted
Control system for doser compensation in an SCR system
AssigneeCummins Inc.
InventorsMert Geveci, Aleksey Yezerets, Neal W. Currier, Michael Haas, Andrew W. Osburn
Life of this patent
Estimating the term…
Abstract
A method includes determining whether selective catalytic reduction (SCR) test conditions are present, and in response to the SCR test conditions being present, operating an SCR aftertreatment system at a number of reduced ammonia to NOx ratio (ANR) operating points. The method further includes determining a deNOx efficiency value corresponding to each of the ANR operating points. The method further includes determining a reductant correction value in response to the deNOx efficiency values corresponding to each of the ANR operating points, and providing a reductant injection command in response to the reductant correction value.
Claims23
A method, comprising:
- determining whether selective catalytic reduction (SCR) test conditions are present;
- in response to the SCR test conditions being present, operating an SCR aftertreatment system at by injecting a reductant at a plurality of reductant amounts to achieve a plurality of ammonia to NOx ratio (ANR) operating points having an ANR less than 1;
- determining a deNOx efficiency value corresponding to each of the plurality of ANR operating points;
- in response to the deNOx efficiency values corresponding to each of the plurality of ANR operating points, determining a reductant correction value in response to a difference between a realized deNOx efficiency change over the plurality of ANR operating points and an expected deNOx efficiency change;
- and
- providing a reductant injection command in response to the reductant correction value;
- wherein the operating the SCR aftertreatment system at a plurality of reduced ammonia to NOx ratio (ANR) operating points comprises operating the SCR aftertreatment system at a first test ANR value that is lower than 0.3 and at a second test ANR value that is greater than 0.6, and the determining the reductant correction value comprises determining a test slope in response to the first test ANR value and the second test ANR value.
4 more elements
An apparatus, comprising:
- an SCR test condition validation module structured to determine whether SCR test conditions are present;
- an injection control module structured to command a first reductant amount for a first test ANR and a second reductant amount for a second test ANR that are each less than 1 in response to the SCR test conditions being present;
- an injector diagnostic module structured to determine a first deNOx efficiency value in response to the first test ANR, and a second deNOx efficiency value in response to the second test ANR;
- and
- an injector correction module structured to determine a reductant correction value in response to a difference between a realized deNOx efficiency change between the first test ANR and the second test ANR and an expected deNOx efficiency change, and to adjust an operational reductant injection amount in response to the reductant correction value;
- wherein the injector diagnostic module is further structured to determine a test slope and a test intercept in response to the first deNOx efficiency value and the second deNOx efficiency value, and wherein the injector correction module is further structured to determine the reductant correction value in response to the test slope and the test intercept.
3 more elements
A system, comprising:
- an internal combustion engine producing an exhaust stream;
- a selective catalytic reduction (SCR) catalyst structured to reduce an amount of NOx in the exhaust stream in the presence of a reductant;
- a reductant injector operationally coupled to the exhaust stream at a position upstream of the SCR catalyst;
- a NOx sensor operationally coupled to the exhaust stream at a position downstream of the SCR catalyst;
- a means for determining an amount of engine-out NOx;
- and
- a controller configured to command the reductant injector to inject a first reductant amount for a first test ANR and a second reductant amount for a second test ANR, with each test ANR having an ANR less than 1, in response to SCR test conditions being present, wherein the controller is further configured to determine a first deNOx efficiency value in response to the first test ANR and a second deNOx efficiency value in response to the second test ANR and a reductant correction value in response to a difference between a realized deNOx efficiency change from the first test ANR to the second test ANR and an expected deNOx efficiency change, and to adjust an operational reductant injection amount in response to the reductant correction value;
- wherein the controller is configured to determine a test slope and a test intercept in response to the first deNOx efficiency value and the second deNOx efficiency value, and to determine the reductant correction value in response to the test slope and the test intercept.
5 more elements
Dependencies are inferred from the claim text.