Ammonia (NH3) storage control system and method based on a nitrogen oxide(NOx) sensor

Patent metadata

Field	Value
Publication number	US-9255510-B2
Application number	US-40015609-A
Country	US
Kind code	B2
Filing date	Mar 9, 2009
Priority date	Mar 9, 2009
Publication date	Feb 9, 2016
Grant date	Feb 9, 2016

Abstract

A control system includes an upstream nitrogen oxide (NO x ) control module that increases an upstream NO x level based on an initial upstream NO x level in an exhaust system, and an ammonia (NH 3 ) storage condition detection module that detects a NH 3 storage condition based on a difference in a downstream NO x level before and after the upstream NO x level is increased. A method includes increasing an upstream NO x level based on an initial upstream NO x level in an exhaust system, and detecting an NH 3 storage condition based on a difference in a downstream NO x level before and after the upstream NO x level is increased.

First claim

What is claimed is:

1. A control system, comprising:
a first electronic circuit configured to increase an upstream nitrogen oxide (NO x ) level for a predetermined period, wherein said upstream NO x level is a NO x level upstream from a selective catalytic reduction (SCR) catalyst in an exhaust system;
a second electronic circuit configured to detect a NH 3 storage condition based on a magnitude of a difference between a first downstream NO x level measured downstream from said SCR catalyst before said upstream NO x level is increased and a second downstream NO x level measured downstream from said SCR catalyst after said upstream NO x level is increased;
a third electronic circuit configured to determine a total NO x mass entering said SCR catalyst as a result of said increase in said upstream NOx level, wherein said first electronic circuit is configured to adjust said predetermined period based on said total NOx mass;
a fourth electronic circuit configured to adjust at least one of a dosing agent injection amount and said upstream NOx level based on said NH 3 storage condition and at least one of:
adjust said dosing agent injection amount using a dosing valve of a dosing system; and
adjust said upstream NOx level using at least one of an exhaust gas recirculation (EGR) valve, actuating a throttle valve, and actuating a fuel injector; and

at least one of said dosing valve, said EGR valve, and said throttle valve.

2. The control system of claim 1 wherein said second electronic circuit is configured to detect a NH 3 slip condition when said difference is less than a minimum downstream NO x level change.

3. The control system of claim 1 wherein said second electronic circuit is configured to detect a low NH 3 storage level condition when said difference is greater than a maximum downstream NO x level change.

4. The control system of claim 1 wherein said first electronic circuit is configured to increase said upstream NOx level by increasing mass airflow (MAF).

5. The control system of claim 1 wherein said first electronic circuit is configured to increase said upstream NO x level by advancing injection timing.

6. The control system of claim 1 wherein said third electronic circuit is configured to determine said total NO x mass based on at least one of an exhaust temperature and said upstream NO x level.

7. A control system, comprising:
a first electronic circuit configured to increase an upstream nitrogen oxide (NO x ) level for a predetermined period, wherein said upstream NO x level is a NO x level upstream from a selective catalytic reduction (SCR) catalyst in an exhaust system;
a second electronic circuit configured to detect a NH 3 storage condition based on a magnitude of a difference between a first downstream NO x level measured downstream from said SCR catalyst before said upstream NO x level is increased and a second downstream NO x level measured downstream from said SCR catalyst after said upstream NO x level is increased;
a third electronic circuit configured to determine a filtered NO x level by filtering said upstream NO x level at a frequency that limits an increase in said filtered NO x level caused by increasing said upstream NO x level for said predetermined period;
a fourth electronic circuit configured to (i) control a dosing agent injection amount based on said filtered NO x level, (ii) adjust at least one of said dosing agent injection amount and said upstream NOx level based on said NH 3 storage condition, and (iii) at least one of:
adjust said dosing agent injection amount using a dosing valve of a dosing system; and
adjust said upstream NOx level using at least one of an exhaust gas recirculation (EGR) valve, actuating a throttle valve, and actuating a fuel injector; and

at least one of said dosing valve, said EGR valve, and said throttle valve.

8. A method, comprising:
increasing an upstream nitrogen oxide (NO x ) level for a predetermined period, wherein said upstream NO x level is a NO x level upstream from a selective catalytic reduction (SCR) catalyst in an exhaust system;
detecting an ammonia (NH 3 ) storage condition based on a magnitude of a difference between a first downstream NO x level measured downstream from said SCR catalyst before said upstream NO x level is increased and a second downstream NO x level measured downstream from said SCR catalyst after said upstream NO x level is increased;
determining a total NO x mass entering said SCR catalyst as a result of said increase in said upstream NOx level;
adjusting said predetermined period based on said total NO x mass;
adjusting at least one of a dosing agent injection amount and said upstream NOx level based on said NH 3 storage condition; and
at least one of:
adjusting said dosing agent injection amount using a dosing valve of a dosing system; and
adjusting said upstream NOx level using at least one of an exhaust gas recirculation (EGR) valve, actuating a throttle valve, and actuating a fuel injector.

9. The method of claim 8 further comprising detecting a NH 3 slip condition when said difference is less than a minimum downstream NO x level change.

10. The method of claim 8 further comprising detecting a low NH 3 storage level condition when said difference is greater than a maximum downstream NO x level change.

11. The method of claim 8 further comprising increasing said upstream NO x level by increasing mass airflow (MAF).

12. The method of claim 8 further comprising increasing said upstream NO x level by advancing injection timing.

13. The method of claim 8 further comprising determining said total NO x mass based on at least one of an exhaust temperature and said upstream NO x level.

14. A method, comprising:
increasing an upstream nitrogen oxide (NO x ) level for a predetermined period, wherein said upstream NO x level is a NO x level upstream from a selective catalytic reduction (SCR) catalyst in an exhaust system;
detecting an ammonia (NH 3 ) storage condition based on a magnitude of a difference between a first downstream NO x level measured downstream from said SCR catalyst before said upstream NO x level is increased and a second downstream NO x level measured downstream from said SCR catalyst after said upstream NO x level is increased; determining a filtered NO x level by filtering said upstream NO x level at a frequency that limits an increase in said filtered NO x level caused by increasing said upstream NO x level for said predetermined period;
controlling a dosing agent injection amount based on said filtered NO x level;
adjusting at least one of said dosing agent injection amount and said upstream NOx level based on said NH 3 storage condition; and
at least one of:
adjusting said dosing agent injection amount using a dosing valve of a dosing system; and
adjusting said upstream NOx level using at least one of an exhaust gas recirculation (EGR) valve, actuating a throttle valve, and actuating a fuel injector.

15. The control system of claim 1 wherein said first electronic circuit is configured to increase said upstream NOx level by a first amount that is based on said upstream NOx level before said upstream NOx level is increased.

16. The method of claim 8 further comprising increasing said upstream NOx level by a first amount that is based on said upstream NOx level before said upstream NOx level is increased.

17. The control system of claim 1 wherein said first, second, and third electronic circuits include at least one of an Application Specific Integrated Circuit (A

Assignees

• Solbrig Charles E
• Yanakiev Ognyan N
• Gm Global Tech Operations Inc

Inventors

• Solbrig Charles E
• Yanakiev Ognyan N

Classifications

• F01N2900/1402

  Exhaust gas composition · CPC title

• F02D41/1462

  with determination means using an estimation · CPC title

• F01N2900/0408

  using a feed-back loop · CPC title

• F02D2041/1469

  with determination means using an estimation · CPC title

• F01N2570/18

  Ammonia · CPC title