Method and system for a first and a second supply of additive to an exhaust gas stream from an internal combustion engine

Patent metadata

Field	Value
Publication number	US-10344647-B2
Application number	US-201615750167-A
Country	US
Kind code	B2
Filing date	Aug 25, 2016
Priority date	Aug 27, 2015
Publication date	Jul 9, 2019
Grant date	Jul 9, 2019

Abstract

Provided are a method and a system for treatment of an exhaust stream, from a combustion engine comprising nitrogen oxides. An estimate of at least one future operating condition for the exhaust treatment system is determined based on a road section ahead of the vehicle. A first additive is input into the exhaust stream to cause a first reduction of nitrogen oxides in a first reduction catalyst device. A second additive is input into the exhaust stream to cause a second reduction of a second amount of nitrogen oxides in a second reduction catalyst device, arranged downstream of the first reduction catalyst device. The first supply of additive is controlled based on the estimated at least one future operating condition, such that the first reduction catalyst device is exposed, over time, to a substoichiometric condition, with respect to the first additive and the first amount of nitrogen oxides.

First claim

The invention claimed is:

1. A method for an exhaust treatment system, arranged for treatment of an exhaust stream resulting from a combustion in a combustion engine in a vehicle, said method comprising:
an estimate of at least one future operating condition for said exhaust treatment system based on a representation of a road section ahead of said vehicle;
a first supply of a first additive into said exhaust stream, which is used at least at a first reduction of a first amount of nitrogen oxides NO x _ 1 in said exhaust stream in a first reduction catalyst device; and
a second supply of a second additive into said exhaust stream, which is used at a second reduction of a second amount of nitrogen oxides NO x _ 2 in said exhaust stream in a second reduction catalyst device, arranged downstream of said first reduction catalyst device, wherein
said first supply is controlled based on said estimated at least one future operating condition in such a manner, that said first reduction catalyst device is exposed, over time, to a substoichiometric condition with respect to said first additive and to said first amount of nitrogen oxides NO x _ 1 .

2. A method according to claim 1 , wherein said estimate of at least one future operating condition comprises an estimate of a future temperature for said first reduction catalyst device and/or for said second reduction catalyst device.

3. A method according to claim 1 , wherein said estimate of at least one future operating condition comprises an estimate of a future conversion degree of additive for said first reduction catalyst device and/or for said second reduction catalyst device.

4. A method according to claim 1 , wherein said estimate of at least one future operating condition comprises an estimate of a future mass flow for said exhaust stream through said exhaust treatment system.

5. A method according to claim 1 , wherein said estimate of at least one future operating condition comprises an estimate of a future soot deposit in a particulate filter, arranged downstream of said first reduction catalyst device in said exhaust treatment system.

6. A method according to claim 1 , wherein:
said first reduction catalyst device comprises a catalytic filter, wherein said catalytic filter comprises an at least partly catalytic coating with reduction characteristics; and
said estimate of at least one future operating condition comprises an estimate of a future soot deposit in said catalytic filter.

7. A method according to claim 1 , wherein said estimate of at least one future operating condition comprises an estimate of a future coverage degree of additive for said first reduction catalyst device and/or for said second reduction catalyst device.

8. A method according to claim 1 , wherein said estimate of at least one future operating condition comprises an estimate of a future residue of additive for said first reduction catalyst device and/or for said second reduction catalyst device.

9. A method according to claim 1 , wherein:
said first reduction is preceded by a first oxidation of compounds comprising one or more of nitrogen, carbon and hydrogen in said exhaust stream; and
said estimate of at least one future operating condition comprises an estimate of a future value (NO 2 _ 1 /NO x _ 1 ) est for a ratio between a first amount of nitrogen dioxide NO 2 _ 1 and a first amount of nitrogen oxides NO x _ 1 reaching said first reduction catalyst device.

10. A method according to claim 1 , wherein:
said second reduction is preceded by a second oxidation of compounds comprising one or more of nitrogen, carbon and hydrogen in said exhaust stream; and
said estimate of at least one future operating condition comprises an estimate of a future value (NO 2 _ 2 /NO x _ 2 ) est for a ratio between a second amount of nitrogen dioxide NO 2 _ 2 and a second amount of nitrogen oxides NO x _ 2 reaching said second reduction catalyst device.

11. A method according to claim 1 , wherein said estimate of at least one future operating condition comprises an estimate of a future power output for said combustion engine, wherein said future operating condition is estimated based on said power output.

12. A method according to claim 1 , wherein said representation of said road section ahead of said vehicle comprises information on one or several of:
a topography for said road section;
a curvature for said road section;
a traffic situation for said road section;
road works for said road section;
weather conditions for said road section;
road conditions for said road section; and
a speed limit for said road section.

13. A method according to claim 1 , wherein said representation of said road section is determined based on one or more of:
positioning information;
sensor information;
information provided by other vehicles; and
map information.

14. A method according to claim 1 , wherein said substoichiometric condition over time, with respect to said first additive and to said first amount of nitrogen oxides NO x _ 1 , corresponds to an ammonia/nitrogen oxides ratio (ANR; Ammonia to No x ratio) over time with a value below 1; ANR<1.

15. A method according to claim 14 , wherein said ammonia/nitrogen oxides ratio ANR over time corresponds to a value in the group of:
ANR<0.5;
ANR<0.6;
ANR<0.7; and
ANR<0.8.

16. A method according to claim 1 , wherein said substoichiometric condition over time, with respect to said first additive and to said first amount of nitrogen oxides NO x _ 1 , depends on one or more characteristics for said first reduction catalyst device.

17. A method according to claim 1 , wherein said control of said first supply of said first additive is carried out in such a manner, that said first reduction catalyst device is exposed to said substoichiometric condition except when time-limited special operating conditions prevail for said combustion engine.

18. A method according to claim 17 , wherein said time-limited special operating conditions comprise transient operating conditions for said combustion engine.

19. A method according to claim 17 , wherein said time-limited special operating conditions are so limited in time, that said accumulation of soot in a particulate filter in said exhaust treatment system exceeding a soot threshold value may substantially be avoided, since nitrogen dioxide NO 2 , which may be used to facilitate an oxidation of soot particles in said particulate filter, is available in said particulate filter except when said time-limited special operating conditions prevail.

20. A method according to claim 17 , wherein said time-limited special operating conditions are so limited in time, that an accumulation of soot in a catalytic filter in said exhaust treatment system exceeding a soot threshold value may substantially be avoided, since nitrogen dioxide NO 2 , which may be used to facilitate an oxidation of soot particles in said catalytic filter, is available in said catalytic filter except when said time-limited special operating conditions prevail.

21. A method according to claim 17 , wherein said time-limited special operating conditions comprise operating modes, for which said first reduction of said first amount of nitrogen oxides NO x _ 1 are given a higher priority than an oxidation of soot particles in said exhaust treatment system.

22. A method according to claim 17 , wherein said time-limited special operating conditions comprise

Assignees

• Scania Cv Ab

Inventors

• Nilsson Magnus

Classifications

• G08G1/096791

  where the origin of the information is another vehicle · CPC title

• G08G1/096775

  where the origin of the information is a central station · CPC title

• G08G1/096758

  where no selection takes place on the transmitted or the received information · CPC title

• G08G1/096716

  where the received information does not generate an automatic action on the vehicle control · CPC title

• G08G1/09626

  where the origin of the information is within the own vehicle, e.g. a local storage device, digital map · CPC title