APPARATUS, SYSTEM, AND METHOD FOR NOx SIGNAL CORRECTION IN FEEDBACK CONTROLS OF AN SCR SYSTEM
First Claim
1. An apparatus for reducing NOx emissions in an engine exhaust gas stream of an:
- engine system, comprising;
a NOx reduction target module configured to determine a NOx reduction requirement, the NOx reduction requirement comprising an amount of NOx in the exhaust gas stream to be reduced on a selective catalytic reduction (SCR) catalyst;
a tailpipe NOx module configured to determine a sensed amount of NOx exiting the engine system;
a signal correction algorithm module configured to determine a corrected amount of NOx exiting the engine system based at least partially on the sensed amount of NOx exiting the engine system;
a feedback ammonia target module configured to determine a feedback ammonia addition requirement, the feedback ammonia addition requirement comprising an amount of ammonia added to the exhaust gas stream to achieve the NOx reduction requirement, wherein the feedback ammonia addition requirement is based at least partially on the corrected amount of NOx exiting the engine system; and
a reductant target module configured to determine a reductant injection requirement, the reductant injection requirement comprising an amount of reductant added to the exhaust gas stream to achieve the feedback ammonia addition requirement.
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Accused Products
Abstract
For example, according to one representative embodiment, an apparatus for reducing NOx emissions in an engine exhaust includes a NOx reduction target module configured to determine a NOx reduction requirement. The apparatus also includes a tailpipe NOx module configured to determine a sensed amount of NOx exiting the engine system and a signal correction algorithm module configured to determine a corrected amount of NOx exiting the engine system based at least partially on the sensed amount of NOx exiting the engine system. The apparatus also includes a feedback ammonia target module configured to determine a feedback ammonia addition requirement. The feedback ammonia addition requirement includes an amount of ammonia added to the exhaust gas stream to achieve the NOx reduction requirement in response to the corrected amount of NOx exiting the engine system. The apparatus also includes a reductant target module that is configured to determine a reductant injection requirement.
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Citations
20 Claims
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1. An apparatus for reducing NOx emissions in an engine exhaust gas stream of an:
engine system, comprising; a NOx reduction target module configured to determine a NOx reduction requirement, the NOx reduction requirement comprising an amount of NOx in the exhaust gas stream to be reduced on a selective catalytic reduction (SCR) catalyst; a tailpipe NOx module configured to determine a sensed amount of NOx exiting the engine system; a signal correction algorithm module configured to determine a corrected amount of NOx exiting the engine system based at least partially on the sensed amount of NOx exiting the engine system; a feedback ammonia target module configured to determine a feedback ammonia addition requirement, the feedback ammonia addition requirement comprising an amount of ammonia added to the exhaust gas stream to achieve the NOx reduction requirement, wherein the feedback ammonia addition requirement is based at least partially on the corrected amount of NOx exiting the engine system; and a reductant target module configured to determine a reductant injection requirement, the reductant injection requirement comprising an amount of reductant added to the exhaust gas stream to achieve the feedback ammonia addition requirement. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for reducing NOx emissions in an engine exhaust gas stream of an engine system, the method comprising the steps of:
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determining a NOx reduction requirement, the NOx reduction requirement comprising an amount of NOx in the exhaust gas stream to be reduced on a selective catalytic reduction (SCR) catalyst; determining a feedback ammonia addition requirement, the feedback ammonia addition requirement comprising an amount of ammonia added to the exhaust gas stream to achieve the NOx reduction requirement in response to a corrected amount of NOx exiting the engine system; determining the corrected amount of NOx exiting the engine system; and determining a reductant injection requirement, the reductant injection requirement comprising an amount of reductant added to the exhaust gas stream to achieve the feedback ammonia addition requirement. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A system for reducing NOx emissions in an engine exhaust, the system comprising:
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an internal combustion engine producing an exhaust gas stream; a selective catalytic reduction (SCR) catalyst that reduces NOx emissions in the exhaust gas stream in the presence of a reductant; a reductant injector that injects reductant into the exhaust gas stream upstream of the SCR catalyst; a tailpipe NOx sensor configured to determine a sensed amount of NOx exiting the engine system; and a controller comprising; a NOx reduction target module configured to determine a NOx reduction requirement, the NOx reduction requirement comprising an amount of NOx in the exhaust gas stream to be reduced on the SCR catalyst; a signal correction algorithm module configured to determine a corrected amount of NOx exiting the engine system based at least partially on the sensed amount of NOx exiting the engine system; a feedback ammonia target module configured to determine a feedback ammonia addition requirement, the feedback ammonia addition requirement comprising an amount of ammonia added to the exhaust gas stream to achieve the NOx reduction requirement in response to a corrected amount of NOx exiting the engine system; and a reductant target module configured to determine a reductant injection requirement, the reductant injection requirement comprising an amount of reductant added to the exhaust gas stream to achieve the feedback ammonia addition requirement. - View Dependent Claims (17, 18, 19)
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20. A method for extracting a tailpipe NOx measurement from a tailpipe NOx signal transmitted from a tailpipe NOx sensor having an ammonia cross-sensitivity, the method comprising the steps of:
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determining an amount of ammonia slipping from the tailpipe; adjusting an ammonia correction factor periodically by dithering the amount of ammonia slipping from the tailpipe; multiplying the amount of ammonia slipping from the tailpipe by the ammonia correction factor to yield a product term; and subtracting the product term from the tailpipe NOx signal to extract the tailpipe NOx measurement.
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Specification