No exhaust emission control method and arrangement
AssigneeVolkswagen Aktiengesellschaft
InventorEkkehard Pott
Life of this patent
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Abstract
NO.sub.X conversion of exhaust gases from lean mixture engines such as Diesel engines is improved by providing a catalytic converter having three zones, the first zone containing an NO.sub.X storage material on a .gamma.-aluminum oxide layer, the second zone having a layer with a noble metal, and the third zone containing an oxygen storage layer.
Claims37
An emission control method for a self-igniting internal combustion engine comprising:
- supplying exhaust gases from a self-igniting internal combustion engine to an NO.sub.X accumulator that is suitable for storing NO.sub.X from the supplied exhaust gas under a first set of operating conditions, and from which, under a second set of operating conditions, the stored NO.sub.X is released for reduction of the NO.sub.X with little or no noble metal in the NO.sub.X accumulator;
- and
- thereafter bringing the exhaust gases into contact with a higher content of a noble metal in the NO.sub.X accumulator or in a downstream catalytic converter.
An emission control method for an internal combustion engine comprising:
- supplying exhaust gases from an internal combustion engine to an NO.sub.X accumulator that is suitable for storing NO.sub.X from the supplied exhaust gas under a first set of operating conditions, and from which, under a second set of operating conditions, the stored NO.sub.X is released for reduction of the NO.sub.X ;
- bringing the exhaust gases into contact with an NO.sub.X accumulator region having little or no capacity for oxygen storage;
- and
- thereafter bringing the exhaust gases into contact with an accumulator region having a higher capacity for oxygen storage either in the NO.sub.X accumulator or downstream.
An internal combustion engine comprising an engine having an exhaust system and an NO.sub.X accumulator in the exhaust system which is suitable for storing NO.sub.X from exhaust gases under a first set of operating conditions, and from which the stored NO.sub.X can be released under a second set of operating conditions for reduction of the NO.sub.X wherein the NO.sub.X accumulator includes at least a first region having little or no noble metal and including a second region in the exhaust system downstream from the first region having a higher content of a noble metal than the first region.
An internal combustion engine comprising an engine having an exhaust system, an NO.sub.X accumulator in the exhaust system which is suitable for storing NO.sub.X from exhaust gases under a first set of operating conditions, and from which the stored NO.sub.X can be released under a second set of operation conditions for reduction of the NO.sub.X, wherein the NO.sub.X accumulator contains a first region with little or no oxygen storage capacity and, including a second region downstream from the first region containing an oxygen accumulator which works in cooperation with an oxidation catalyst.
An internal combustion engine comprising an engine having an exhaust system, at least three exhaust gas treatment regions in the exhaust system including an NO.sub.X accumulator, a first region in the NO.sub.X accumulator containing little or no noble metal, a second region in the NO.sub.X accumulator downstream from the first region containing more noble metal than the first region, and a third region in the exhaust system downstream from the second region containing an oxygen accumulator with a noble metal coating.
Dependencies are inferred from the claim text.