Technique for production of ammonia on demand in a three way catalyst for a passive selective catalytic reduction system
First Claim
1. A method for controlling a powertrain comprising an internal combustion engine including multiple cylinders and an aftertreatment system including a selective catalytic reduction device utilizing ammonia as a reductant, said method comprising:
- depleting oxygen from an ammonia generation catalyst located between the engine and the selective catalytic reduction device and connected to the plurality of the cylinders, including selecting for the cylinders an air fuel ratio within a stoichiometric-to-rich operating range;
after depleting oxygen from the ammonia generation catalyst, initiating an ammonia generation cycle comprisingcooperatively operating a plurality of the cylinders, with some portion of the plurality of cylinders operating at air/fuel ratios in a first stoichiometric-to-rich range conducive to producing NOx and with a remaining portion of the plurality of the cylinders operating at air/fuel ratios in a second range with a more rich air/fuel ratio than the first range conducive to producing molecular hydrogen; and
utilizing the ammonia generation catalyst to produce ammonia.
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Abstract
A powertrain includes an internal combustion engine with multiple cylinders and an aftertreatment system having a selective catalytic reduction device utilizing ammonia as a reductant. An ammonia generation cycle includes operating some portion of the cylinders at an air/fuel ratio conducive to producing molecular hydrogen and some portion of the cylinders at an air/fuel ratio conducive to producing NOx. An ammonia generation catalyst is utilized between the engine and the selective catalytic reduction device to produce ammonia.
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Citations
15 Claims
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1. A method for controlling a powertrain comprising an internal combustion engine including multiple cylinders and an aftertreatment system including a selective catalytic reduction device utilizing ammonia as a reductant, said method comprising:
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depleting oxygen from an ammonia generation catalyst located between the engine and the selective catalytic reduction device and connected to the plurality of the cylinders, including selecting for the cylinders an air fuel ratio within a stoichiometric-to-rich operating range; after depleting oxygen from the ammonia generation catalyst, initiating an ammonia generation cycle comprising cooperatively operating a plurality of the cylinders, with some portion of the plurality of cylinders operating at air/fuel ratios in a first stoichiometric-to-rich range conducive to producing NOx and with a remaining portion of the plurality of the cylinders operating at air/fuel ratios in a second range with a more rich air/fuel ratio than the first range conducive to producing molecular hydrogen; and utilizing the ammonia generation catalyst to produce ammonia. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An apparatus for controlling a powertrain comprising an internal combustion engine including multiple cylinders and an aftertreatment system, comprising:
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a direct injection fuel injection system; said aftertreatment system comprising a selective catalytic reduction device utilizing ammonia as a reductant, and a first ammonia generation catalyst located between the engine and the selective catalytic reduction device; and a controller configured to monitor ammonia production requirements for the selective catalytic reduction device, deplete oxygen from the first ammonia generation catalyst, including selecting for a first pair of the cylinders an air fuel ratio within a stoichiometric-to-rich operating range, and after depleting oxygen from the first ammonia generation catalyst, control the direct injection fuel injection system including effecting different air/fuel ratios within the first pair of the cylinders including operating one of the first pair of the cylinders at an air/fuel ratio in a first stoichiometric-to-rich range conducive to producing NOx based upon the ammonia production requirements, and operating the other of the first pair of cylinders at an air/fuel ratio in a second range with a more rich air/fuel ratio than the first range conducive to producing molecular hydrogen based upon the ammonia production requirements. - View Dependent Claims (11, 12, 13, 14, 15)
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Specification