TECHNIQUE FOR PRODUCTION OF AMMONIA ON DEMAND IN A THREE WAY CATALYST FOR A PASSIVE SELECTIVE CATALYTIC REDUCTION SYSTEM

• US 20100212295A1
• Filed: 02/23/2009
• Published: 08/26/2010
• Est. Priority Date: 02/23/2009
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (Motors Liquidation Co. GUC Trust)
• Inventors: Najt, Paul M., Narayanaswamy, Kushal
• Granted Patent: US 8,424,289 B2
• Time in Patent Office: Days
• US Class Current: 60/285
• CPC Class Codes: F01N 2610/00 Adding substances to exhaust gases
• CPC Class Codes: F01N 3/208 Control of selective catalytic reduction [SCR], e.g. dosing of reducing agent
• CPC Class Codes: F02D 41/0082 per groups or banks F02D41/0087 takes precedence
• CPC Class Codes: F02D 41/0087 Selective cylinder activation, i.e. partial cylinder operation deceleration cut-off F02D41/123
• CPC Class Codes: F02D 41/0235 in relation with the state of the exhaust gas treating apparatus control of exhaust gas treating apparatus per se F01N

Abstract

A powertrain includes an internal combustion engine having 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.

Claims

1. 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:

initiating an ammonia generation cycle comprising cooperatively operating a plurality of the cylinders, with some portion of the plurality of cylinders operating at an air/fuel ratio conducive to producing molecular hydrogen and with some portion of the plurality of the cylinders operating at an air/fuel ratio conducive to producing NOx, and

utilizing an ammonia generation catalyst between the engine and the selective catalytic reduction device and connected to the plurality of the cylinders to produce ammonia.

2. The method of claim 1:

wherein operating the portion of the plurality of cylinders at the air/fuel ratio conducive to producing molecular hydrogen comprises operating said portion at an air/fuel ratio rich of stoichiometry; and

wherein operating the portion of the plurality of cylinders at the air/fuel ratio conducive to producing NOx comprises operating said portion at an air/fuel ratio lean of stoichiometry.

3. The method of claim 1, wherein cooperatively operating the plurality of the cylinders comprises simultaneously adjusting air/fuel ratio in two of the plurality of the cylinders.

4. The method of claim 3, wherein cooperatively operating the plurality of the cylinders further comprises deactivating another one of the plurality of the cylinders.

5. The method of claim 1:

wherein cooperatively operating the plurality of the cylinders comprises combustion cycle to combustion cycle control of the plurality of the cylinders; and

wherein the portion of the plurality of cylinders operating at the air/fuel ratio conducive to producing molecular hydrogen and the portion of the plurality of cylinders operating at the air/fuel ratio conducive to producing NOx can change from combustion cycle to combustion cycle.

6. The method of claim 1, wherein the plurality of cylinders operating at an air/fuel ratio conducive to producing molecular hydrogen are operated with a split fuel injection strategy.

7. The method of claim 6, wherein the split injection strategy includes late combustion hydrocarbon reformation.

8. The method of claim 6, wherein the split injection strategy includes post combustion hydrocarbon reformation.

9. 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:

monitoring operation of the selective catalytic reduction device;

calculating ammonia production requirements for an ammonia generation cycle based upon the operation of the selective catalytic reduction device; and

controlling a plurality of the cylinders connected to a common ammonia generation catalyst based upon the ammonia production requirements, said controlling comprising

operating one of the plurality of the cylinders to an air/fuel ratio calibrated to produce an amount of molecular hydrogen based upon the ammonia production requirements, and

operating one of the plurality of the cylinders to an air/fuel ratio calibrated to produce an amount of NOx based upon the ammonia production requirements.

10. The method of claim 9, wherein controlling said plurality of cylinders further comprises:

operating multiple ones of the plurality of the cylinders to air/fuel ratios calibrated to produce the amount of molecular hydrogen from the multiple ones of the plurality of the cylinders based upon the ammonia production requirements.

11. The method of claim 9, wherein said controlling said plurality of cylinders further comprises:

operating multiple ones of the plurality of the cylinders to air/fuel ratios calibrated to produce the amount of NOx from the multiple ones of the plurality of the cylinders based upon the ammonia production requirements.

12. Apparatus for controlling a powertrain comprising an internal combustion engine including multiple cylinders and an aftertreatment system, comprising:

a direct injection fuel injection system;

said aftertreatment system comprising

a selective catalytic reduction device utilizing ammonia as a reductant, and

an ammonia generation catalyst; and

a controller configured to

monitor ammonia production requirements for the selective catalytic reduction device, and

control the direct injection fuel injection system including effecting different air/fuel ratios within the cylinders including

operating one of the cylinders to an air/fuel ratio calibrated to produce an amount of molecular hydrogen based upon the ammonia production requirements, and

operating one of the cylinders to an air/fuel ratio calibrated to produce an amount of NOx based upon the ammonia production requirements.

13. The apparatus of claim 12, wherein effecting different air/fuel ratios within the cylinders further includes operating a plurality of the cylinders to air/fuel ratios calibrated to produce an amount of molecular hydrogen based upon the ammonia production requirements.

14. The apparatus of claim 12, wherein effecting different air/fuel ratios within the cylinders further includes operating a plurality of the cylinders to air/fuel ratios calibrated to produce an amount of NOx based upon the ammonia production requirements.

15. The apparatus of claim 12, wherein the aftertreatment system further comprises a hydrogen forming catalyst useful for post combustion hydrocarbon reformation.