Aftertreatment system and method
AssigneeCaterpillar Inc.
InventorsPaul R. Moore, Ling Deng, Wilce Damion Williams
Life of this patent
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Abstract
A system for the treatment of exhaust gases from an internal combustion engine with a combustion chamber includes an upstream DEF injector disposed to introduce DEF to the combustion chamber and a close-coupled SCR catalyst downstream of and in close-coupled relation to the internal combustion engine. Downstream of the close-coupled SCR catalyst may be a primary SCR catalyst and a primary DEF injector. The system may operate to reduce NO2 in the close-coupled SCR catalyst during low-load conditions of the internal combustion engine and reduce NO2 in the primary SCR catalyst during loaded conditions.
Claims19
A machine comprising:
- an internal combustion engine including a combustion chamber;
- an air intake system upstream of the internal combustion engine to direct intake air to the combustion chamber;
- an exhaust system downstream of the internal combustion engine to direct exhaust gases from the combustion chamber;
- an upstream diesel exhaust fluid (DEF) injector disposed to selectively introduce DEF to the combustion chamber;
- a close-coupled selective catalytic reduction (SCR) catalyst disposed in the exhaust system in a close-coupled relation to the internal combustion engine to receive raw exhaust gases therefrom and to reduce nitrogen oxides (NOX) to nitrogen (N2) and water (H2O) during a low-load condition of the internal combustion engine
- a primary SCR catalyst and a primary DEF injector downstream of the close-coupled SCR catalyst, the primary DEF injector disposed to introduce DEF to the exhaust gases, the primary DEF injector selectively activated to reduce NOX to N2 and H2O in the primary SCR catalyst during a loaded condition of the internal combustion engine.
A method of treating exhaust gases from an internal combustion engine comprising:
- introducing diesel exhaust fluid (DEF) via an upstream DEF injector to a combustion chamber of an internal combustion engine during a low-load condition of the engine;
- directing raw exhaust gases including the DEF from the combustion chamber to a close-coupled selective catalyst reduction (SCR) catalyst to reduce nitrogen oxides (NOX) to nitrogen (N2) and water (H2O) during a low-load condition of the internal combustion engine;
- directing the exhaust gases from the close-coupled SCR catalyst to a primary aftertreatment system including a primary SCR injector and a primary SCR catalyst downstream of the close-coupled SCR catalyst;
- and
- introducing DEF via a primary DEF injector to the primary SCR catalyst during a loaded condition of the internal combustion engine to reduce NOX to N2 and H2O during the loaded condition.
A system for controlling selective catalytic reduction of exhaust gases from an internal combustion engine comprising:
- an upstream diesel exhaust fluid (DEF) injector disposed upstream of the internal combustion engine to selectively introduce DEF to a combustion chamber of an internal combustion engine;
- a close-coupled selective catalytic reduction (SCR) catalyst disposed downstream of and in a close-coupled relation to the internal combustion engine;
- a primary SCR catalyst disposed downstream of the close-coupled SCR catalyst;
- a primary DEF injector disposed downstream of the close-coupled SCR catalyst to selectively introduce DEF to the primary SCR catalyst;
- and
- an electronic controller configured to measure an engine load applied to the internal combustion engine, to assess whether the engine load indicates a low-load condition or a loaded condition, and to activate the upstream DEF injector in the event of a low-load condition or activate the primary DEF injector in the event of a loaded condition.
Dependencies are inferred from the claim text.