On-board ammonia generation and exhaust after treatment system using same

• US 20070092426A1
• Filed: 10/03/2005
• Published: 04/26/2007
• Est. Priority Date: 10/03/2005
• Status: Active Grant

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Driscoll, Josh, Robel, Wade, Urven, Roger, Brown, Cory
• Granted Patent: US 7,685,809 B2
• Time in Patent Office: Days
• US Class Current: 423/352
• CPC Class Codes: B01D 53/90 Injecting reactants
• CPC Class Codes: B01D 53/9409 Nitrogen oxides
• CPC Class Codes: B01D 53/9495 Controlling the catalytic process
• CPC Class Codes: C01C 1/04 Preparation of ammonia by synthesis in the gas phasepreparation or purification of gas mixtures for ammonia synthesis C01B3/025
• CPC Class Codes: F01N 13/009 having two or more separate purifying devices arranged in series
• CPC Class Codes: F01N 13/011 having two or more purifying devices arranged in parallel
• CPC Class Codes: F01N 13/107 More than one exhaust manifold or exhaust collector
• CPC Class Codes: F01N 2240/25 an ammonia generator
• CPC Class Codes: F01N 2610/03 the substance being hydrocarbons, e.g. engine fuel
• CPC Class Codes: F01N 3/2073 with means for generating a reducing substance from the exhaust gases
• CPC Class Codes: F02D 2250/36 Control for minimising NOx emissions
• 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
• CPC Class Codes: F02D 41/402 Multiple injections
• CPC Class Codes: F02M 2200/46 Valves, e.g. injectors, with concentric valve bodies
• CPC Class Codes: F02M 45/086 Having more than one injection-valve controlling discharge orifices
• CPC Class Codes: F02M 47/027 Electrically actuated valves draining the chamber to release the closing pressure
• CPC Class Codes: F02M 61/182 Discharge orifices being situated in different transversal planes with respect to valve member direction of movement
• CPC Class Codes: F02M 63/0064 Two or more actuators acting on two or more valve bodies

Abstract

Often NOx selective catalysts that use ammonia to reduce NOx within exhaust to a harmless gas require on-board storage of ammonia which can be hazardous and inconvenient. In order to generate ammonia in exhaust, the present disclosure increases a NOx concentration in exhaust from at least one combustion chamber, at least in part, by injecting fuel in a predetermined increased NOx generation sequence that includes a first injection during non-auto ignition conditions and a second injection during auto ignition conditions. At least a portion of the NOx is converted to ammonia by passing at least a portion of the exhaust with the increased NOx concentration over an ammonia-producing catalyst.

Claims

1. A method of generating ammonia in exhaust comprising the steps of:

increasing a NOx concentration in exhaust from at least one combustion chamber, at least in part, by injecting fuel in a predetermined increased NOx generation sequence including at least a first injection during non-auto ignition conditions and a second injection during auto ignition conditions; and

converting at least a portion of the NOx to ammonia, at least in part, by passing at least a portion of the exhaust with the increased NOx concentration in proximity of an ammonia-producing catalyst.

2. The method of claim 1 wherein the step of increasing NOx includes a step of injecting the first injection in a first spray pattern with a small average angle relative to a centerline of the combustion chamber and injecting the second injection in a second spray pattern with a large average angle relative to the centerline of the combustion chamber.

3. The method of claim 1 including a step of adding unburnt fuel into the exhaust, at least in part, by injecting an additional amount of fuel into a non-combustible environment of the combustion chamber during at least one of an expansion stroke and exhaust stroke.

4. The method of claim 1 including a step of adding unburnt fuel into the exhaust, at least in part, by injecting fuel into the exhaust passage downstream from the combustion chamber.

5. The method of claim 1 including the steps of:

mixing the ammonia with other exhaust; and

passing the ammonia and other exhaust over a NOx selective catalyst.

6. The method of claim 5 including a step of setting an ammonia production amount to reduce an expected NOx concentration from the other exhaust.

7. The method of claim 6 wherein the step of increasing NOx includes a step of injecting the first injection in a first spray pattern including a small average angle relative to a centerline of the combustion chamber and injecting the second injection in a second spray patter includes a large average angle relative to the centerline of the combustion chamber;

and

adding unburnt fuel into the exhaust, at least in part, by injecting fuel into the exhaust passage upstream from the ammonia-producing catalyst or injecting an additional amount of fuel into a non-combustible environment of the combustion chamber during at least one of an expansion stroke and exhaust stroke.

8. An exhaust after treatment system comprising:

at least one combustion chamber including a piston operable to reciprocate within the combustion chamber;

an ammonia-producing catalyst being positioned in a first section of an exhaust passage fluidly connected to the combustion chamber;

a NOx selective catalyst being positioned in a second section of the exhaust passage fluidly connected to the first section and downstream from the ammonia-producing catalyst;

at least one fuel injector operable to inject fuel into the combustion chamber; and

an electronic control module being in communication with the at least one fuel injector and including an increased NOx generation algorithm operable to signal the fuel injector to inject fuel in a predetermined increased NOx generation sequence including a first fuel injection during non-auto ignition conditions and a second fuel injection during auto ignition conditions.

9. The exhaust after treatment system of claim 8 wherein the at least one fuel injector being operable to inject at least a first spray pattern with a small average angle relative to a centerline of the combustion chamber and a second spray pattern with a large average angle relative to the centerline of the combustion chamber;

and

the first fuel injection of the predetermined increased NOx generation sequence includes the first spray pattern and the second fuel injection includes the second spray pattern.

10. The exhaust after treatment system of claim 8 wherein the at least one fuel injector includes a plurality of fuel injectors;

and

the increased NOx generation algorithm operable to signal less than all of the plurality of fuel injectors to inject fuel in the predetermined increased NOx generation sequence.

11. The exhaust after treatment system of claim 10 wherein the at least one combustion chamber includes a plurality of combustion chambers;

and

a first portion of the plurality of combustion chambers being fluidly connected to the first section of the exhaust passage via a first exhaust manifold, and a second portion of the plurality of combustion chambers being fluidly connected to the second section of the exhaust passage via a second exhaust manifold.

13. The exhaust after treatment system of claim 11 wherein the increased NOx generation algorithm being operable to signal only the fuel injectors associated with the first portion of the plurality of combustion chambers to inject fuel in the predetermined increased NOx generation sequence.

14. The exhaust after treatment system of claim 13 wherein the first injection of the predetermined increased NOx generation sequence includes a first spray pattern with a small average angle relative to a centerline of the combustion chamber and the second injection includes a second spray pattern with a large average angle relative to the centerline of the combustion chamber;

and

the increased NOx generation algorithm includes a setting algorithm operable to set a NOx production amount to correspond to an ammonia production amount operable to reduce an expected NOx concentration created by the second portion of the plurality of combustion chambers.

12. The exhaust after treatment system of 11 wherein the increased NOx generation algorithm includes a setting algorithm operable to set a NOx production amount to correspond to an ammonia production amount operable to reduce an expected NOx concentration created by the second portion of the plurality of combustion chambers.

15. An article comprising:

a computer readable data storage medium; and

an increased NOx generation algorithm stored on the medium and operable to signal at least one fuel injector to inject fuel in a predetermined increased NOx injection sequence including a first injection during non-auto ignition conditions and a second injection during auto-ignition conditions within a combustion chamber.

16. The article of claim 15 wherein the increased NOx generation algorithm including a first spray pattern algorithm operable to signal the at least one fuel injector in a first spray pattern with a small average angle relative to a centerline of the combustion chamber, and a second spray pattern algorithm operable to signal that at least one fuel injector to inject in a second spray pattern with a large average angle relative to the centerline of the combustion chamber.

17. The article of claim 16 wherein the first spray pattern algorithm being operable to signal the at least one fuel injector to inject the first injection in the first spray pattern, and the second spray pattern algorithm being operable to signal the at least one fuel injector to inject the second injection in the second spray pattern.

18. The article of claim 17 wherein the increased NOx generation algorithm includes a setting algorithm operable to set a NOx production amount to correspond to an ammonia production amount operable to reduce an expected NOx concentration created, in part, by the at least one different fuel injector.