Method of adjusting the dosage of reductant in an SCR catalyst

Patent metadata

Field	Value
Publication number	US-11280241-B2
Application number	US-202017082140-A
Country	US
Kind code	B2
Filing date	Oct 28, 2020
Priority date	Oct 28, 2019
Publication date	Mar 22, 2022
Grant date	Mar 22, 2022

Abstract

A method of adjusting the dosage of a reductant for an SCR catalyst, comprising: determining (110) an expected temperature profile in at least one axial section of the catalyst (70) for a defined period of time (tSim); firstly simulating (120) the resulting amount of reductant beyond the at least one section of the catalyst with a first defined dosage of the reductant depending on the expected temperature profile determined; comparing the first simulated amount of reductant with a limit; depending on the result of the comparison, choosing a second defined dosage and secondly simulating (130, 160) a resulting amount of reductant beyond the at least one section of the catalyst (70) with the second dosage; comparing the second simulated amount of reductant with the limit; and adjusting (140, 150, 170, 180, 190, 195) the dosage for injection of the reductant into the catalyst based on the first and/or second comparison.

First claim

The invention claimed is:

1. A method of adjusting a dosage of reductant in an SCR catalyst ( 70 ), the method comprising:
determining ( 110 ) an expected temperature profile in at least one axial section of the catalyst ( 70 ) for a defined period of time (t Sim ), wherein the expected temperature profile is associated with a predetermined driving situation of a driving segment;
firstly simulating ( 120 ) a resulting amount of reductant beyond the at least one section of the catalyst with a first defined dosage of the reductant depending on the expected temperature profile determined;
comparing the first simulated amount of reductant with a limit;
depending on a result of the comparison, choosing a second defined dosage and secondly simulating ( 130 , 160 ) a resulting amount of reductant beyond the at least one section of the catalyst ( 70 ) with the second dosage;
comparing the second simulated amount of reductant with the limit; and
adjusting ( 140 , 150 , 170 , 180 , 190 , 195 ) the dosage for injection of the reductant into the catalyst based at least in part on the first comparison.

2. The method according to claim 1 , further comprising determining the defined period of time (t Sim ) as a function of a temperature upstream of the catalyst ( 70 ).

3. The method according to claim 2 , further comprising determining at least one sampling rate that defines multiple junctures (t(i)) within the defined period of time for the performance of in each case the first ( 120 ) and of the second ( 130 , 160 ) simulation.

4. The method according to claim 1 , wherein the first defined dosage is a fill level-maintaining dosage for the catalyst, and wherein the second defined dosage is zero if the first comparison with the limit shows that the limit is exceeded, and wherein the second defined dosage is greater than the fill level-maintaining dosage if the first comparison with the limit shows that the limit is not exceeded.

5. The method according to claim 1 , wherein the adjusting of the dosage for injection of the reductant into the catalyst comprises interpolation ( 140 , 180 ) between the first defined dosage and the second defined dosage.

6. The method according to claim 1 , further comprising:
multiplying the dosage by an adaptation factor if the temperature in the defined temperature profile exceeds a defined temperature limit.

7. The method according to claim 1 , further comprising:
determining ( 110 ) the expected temperature profile in the catalyst taking account of expected driving behavior.

8. The method according to claim 7 , wherein the determining of the expected temperature profile ( 110 ) comprises:
stipulating predetermined driving situations and determining a likely temperature rise upstream of the catalyst for each of the predetermined driving situations.

9. The method according to claim 1 , further comprising:
dividing a catalyst into multiple axial sections, and performing the adjustment of the dosage for each of the axial sections over the defined period of time.

10. The method according to claim 1 , further comprising:
injecting reductant into the catalyst on the basis of the dosage determined.

11. The method according to claim 3 , wherein the first defined dosage is a fill level-maintaining dosage for the catalyst, and wherein the second defined dosage is zero if the first comparison with the limit shows that the limit is exceeded, and wherein the second defined dosage is greater than the fill level-maintaining dosage if the first comparison with the limit shows that the limit is not exceeded.

12. The method according to claim 11 , wherein the adjusting of the dosage for injection of the reductant into the catalyst comprises interpolation ( 140 , 180 ) between the first defined dosage and the second defined dosage.

13. The method according to claim 12 , further comprising:
multiplying the dosage by an adaptation factor if the temperature in the defined temperature profile exceeds a defined temperature limit.

14. The method according to claim 13 , further comprising:
determining ( 110 ) the expected temperature profile in the catalyst taking account of expected driving behavior.

15. The method according to claim 14 , wherein the determining of the expected temperature profile ( 110 ) comprises:
stipulating predetermined driving situations and determining a likely temperature rise upstream of the catalyst for each of the predetermined driving situations.

16. The method according to claim 15 , further comprising:
dividing a catalyst into multiple axial sections, and performing the adjustment of the dosage for each of the axial sections over the defined period of time.

17. The method according to claim 16 , further comprising:
injecting reductant into the catalyst on the basis of the dosage determined.

18. A computer unit for adjusting a dosage of reductant in an SCR catalyst ( 70 ), the computer unit comprising an electronic processor configured to:
determine ( 110 ) an expected temperature profile in at least one axial section of the catalyst ( 70 ) for a defined period of time (t Sim ), wherein the expected temperature profile is associated with a predetermined driving situation of a driving segment;
firstly simulate ( 120 ) a resulting amount of reductant beyond the at least one section of the catalyst with a first defined dosage of the reductant depending on the expected temperature profile determined;
compare the first simulated amount of reductant with a limit;
depending on a result of the comparison, choosing a second defined dosage and secondly simulate ( 130 , 160 ) a resulting amount of reductant beyond the at least one section of the catalyst ( 70 ) with the second dosage;
compare the second simulated amount of reductant with the limit; and
adjust ( 140 , 150 , 170 , 180 , 190 , 195 ) the dosage for injection of the reductant into the catalyst based at least in part on the first comparison.

19. A non-transitory computer-readable medium for adjusting a dosage of reductant in an SCR catalyst ( 70 ), the non-transitory computer-readable medium containing computer-executable instructions that, when executed by one or more processors, cause the one or more processors to:
determine ( 110 ) an expected temperature profile in at least one axial section of the catalyst ( 70 ) for a defined period of time (t Sim ), wherein the expected temperature profile is associated with a predetermined driving situation of a driving segment;
firstly simulate ( 120 ) a resulting amount of reductant beyond the at least one section of the catalyst with a first defined dosage of the reductant depending on the expected temperature profile determined;
compare the first simulated amount of reductant with a limit;
depending on a result of the comparison, choosing a second defined dosage and secondly simulate ( 130 , 160 ) a resulting amount of reductant beyond the at least one section of the catalyst ( 70 ) with the second dosage;
compare the second simulated amount of reductant with the limit; and
adjust ( 140 , 150 , 170 , 180 , 190 , 195 ) the dosage for injection of the reductant into the catalyst based at least in part on the first comparison.

20. The method according to claim 1 , further comprising adjusting ( 140 , 150 , 170 , 180 , 190 , 195 ) the dosage for injection of the reductant into the catalyst based at least in part on the first and second comparison.

Assignees

• Bosch Gmbh Robert

Inventors

• Fritsch Andreas

Classifications

• F01N9/00 Primary

  Electrical control of exhaust gas treating apparatus (monitoring or diagnostic devices for exhaust-gas treatment apparatus F01N11/00; conjoint electrical control of two or more combustion engine functions F02D43/00) · CPC title

• F01N3/208 Primary

  Control of selective catalytic reduction [SCR], e.g. by adjusting the dosing of reducing agent · CPC title

• F01N2900/1814

  Tank level · CPC title

• F01N2610/02

  the substance being ammonia or urea · CPC title

• F01N2900/0406

  using a model with a division of the catalyst or filter in several cells · CPC title