COMBUSTION DRIVEN AMMONIA GENERATION STRATEGIES FOR PASSIVE AMMONIA SCR SYSTEM
First Claim
1. A method for controlling ammonia generation in an exhaust gas feedstream output from an internal combustion engine equipped with an exhaust aftertreatment system including a first aftertreatment device, comprising:
- executing an ammonia generation cycle to generate ammonia on the first aftertreatment device, said ammonia generation cycle comprising;
determining a desired air-fuel ratio of the engine to generate an engine-out exhaust gas feedstream conducive for generating ammonia on the first aftertreatment device; and
selectively altering operation of a selected combination of a plurality of cylinders of the engine such that the desired air-fuel ratio of the engine is achieved.
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Abstract
A method for controlling ammonia generation in an exhaust gas feedstream output from an internal combustion engine equipped with an exhaust aftertreatment system including a first aftertreatment device includes executing an ammonia generation cycle to generate ammonia on the first aftertreatment device. A desired air-fuel ratio output from the engine and entering the exhaust aftertreatment system conducive for generating ammonia on the first aftertreatment device is determined. Operation of a selected combination of a plurality of cylinders of the engine is selectively altered to achieve the desired air-fuel ratio entering the exhaust aftertreatment system.
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Citations
20 Claims
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1. A method for controlling ammonia generation in an exhaust gas feedstream output from an internal combustion engine equipped with an exhaust aftertreatment system including a first aftertreatment device, comprising:
executing an ammonia generation cycle to generate ammonia on the first aftertreatment device, said ammonia generation cycle comprising; determining a desired air-fuel ratio of the engine to generate an engine-out exhaust gas feedstream conducive for generating ammonia on the first aftertreatment device; and selectively altering operation of a selected combination of a plurality of cylinders of the engine such that the desired air-fuel ratio of the engine is achieved. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method for controlling ammonia generation in an exhaust gas feedstream output from an internal combustion engine equipped with an exhaust aftertreatment system including a three-way catalytic device and an ammonia-selective catalytic reduction device, comprising:
executing an ammonia generation cycle to generate ammonia on the three-way catalytic device, said ammonia generation cycle comprising; determining a desired air-fuel ratio of the engine to generate an engine-out exhaust gas feedstream including nitric oxide, carbon monoxide, hydrogen and unburned hydrocarbons that enters the exhaust aftertreatment system and converts to ammonia on the three-way catalytic device, and one of; operating all cylinders of the engine to dither around the desired air-fuel ratio; and operating each of a selected combination of a plurality of cylinders of the engine at a biased air-fuel ratio and each of the remaining cylinders at an un-biased air-fuel ratio resulting in operation at an average air-fuel ratio of the selected combination of the plurality of cylinders and the remaining cylinders that is equal to the desired air-fuel ratio. - View Dependent Claims (15, 16, 17, 18, 19)
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20. An exhaust aftertreatment system for an internal combustion engine, comprising:
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a catalytic device formulated to produce ammonia from an exhaust gas feedstream that includes nitric oxide, carbon monoxide, hydrogen and unburned hydrocarbons, the catalytic device close-coupled to an exhaust manifold of the internal combustion engine and fluidly coupled to an ammonia-selective catalytic reduction device located downstream of the catalytic device; a control module; executing an ammonia generation cycle to generate ammonia on the catalytic device; determining a desired air-fuel ratio of the engine to generate an engine-out exhaust gas feedstream conducive for generating ammonia on the catalytic device; and altering operation of a selected combination of a plurality of cylinders of the engine such that the desired air-fuel ratio of the engine is achieved.
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Specification