Methods for controlling nitrous oxide emissions
AssigneeFord Global Technologies, LLC
InventorsChristine Kay Lambert, William Charles Ruona
Life of this patent
Estimating the term…
Abstract
Systems and methods for controlling nitrous oxide emissions are described. In one particular example, nitrous oxide formed in the exhaust system of a diesel hybrid vehicle is routed through an oxidation catalyst heated by an external source such as an electric heater. Then, the catalyst is heated from the external source to reduce nitrous oxide formation within the exhaust system by increasing the catalyst temperature above a temperature range associated with nitrous oxide generation.
Claims20
A method for controlling engine emissions, comprising:
- routing exhaust gases from the engine through an oxidation catalyst which includes a washcoat with palladium or platinum or both;
- inferring N2O formation from said catalyst from one or more of, catalyst temperature, HC to NOx ratio or NO2 to NOx ratio in said engine exhaust gases;
- and
- reducing said N2O formation when said catalyst is operating within a temperature range associated with N2O formation.
A method for controlling emissions for a diesel engine, comprising:
- routing exhaust gases from the engine through an oxidation catalyst which includes a washcoat with palladium or platinum or both;
- routing exhaust gases from said oxidation catalyst into a selective reduction catalyst;
- adding ammonia to said selective reduction catalyst under predetermined conditions to reduce NOx;
- inferring N2O formation from said oxidation catalyst from, temperature of said catalyst, HC and NOx and NO2 in said engine exhaust gases;
- inferring N2O out of said selective reduction catalyst from temperature of said selective reduction catalyst, said inferred N2O formation from said oxidation catalyst, and said ammonia;
- and
- heating said oxidation catalyst from an external source to reduce said N2O out of said selective reduction catalyst when said oxidation catalyst temperature is below a predetermined range and said N2O out of said selective reduction catalyst exceeds a preselected amount.
A method for controlling emissions for a diesel engine in a hybrid vehicle driven by either the diesel engine or an electric motor, comprising:
- routing exhaust gases from the engine through an oxidation catalyst which includes a washcoat with palladium or platinum or both;
- routing exhaust gases from said oxidation catalyst into a selective reduction catalyst;
- adding ammonia to said selective reduction catalyst under predetermined conditions to reduce NOx;
- inferring N2O formation from said oxidation catalyst from, temperature of said catalyst, ratio of HC to NOx and NO2 in said engine exhaust gases;
- inferring N2O out of said selective reduction catalyst from temperature of said selective reduction catalyst, said inferred N2O formation from said oxidation catalyst, NOx from the diesel engine, and said ammonia;
- heating said oxidation catalyst with an electric heater to reduce said N2O formation from said oxidation catalyst when said oxidation catalyst temperature is below a predetermined range and said inferred N2O out of said selective reduction catalyst exceeds a preselected amount;
- and
- discontinuing said electric heating when said oxidation catalyst temperature exceeds said predetermined range.
Dependencies are inferred from the claim text.