Methods and systems for an exhaust gas aftertreatment arrangement

Patent metadata

Field	Value
Publication number	US-10865678-B2
Application number	US-201916290728-A
Country	US
Kind code	B2
Filing date	Mar 1, 2019
Priority date	Mar 8, 2018
Publication date	Dec 15, 2020
Grant date	Dec 15, 2020

Abstract

Methods and systems are provided for an exhaust gas arrangement. In one example, a system comprises an air supply device arranged between a first LNT and a second LNT. The air supply device positioned to adjust an air/fuel ratio and a temperature of exhaust gas flowing to the second LNT and devices downstream thereof.

First claim

The invention claimed is:

1. A system comprising:
a first lean NO x trap arranged upstream of a second lean NO x trap in an exhaust passage;
an air injector arranged between the first and second lean NO x traps;
a selective catalytic reduction device arranged downstream of the second lean NO x trap; and
a controller with computer-readable instructions stored on non-transitory memory thereof that when executed enable the controller to:
adjust an air flow from the air injector during a regeneration of the first lean NO x trap; and
adjust the air flow during the regeneration of the second lean NO x trap with a rich exhaust gas in response to a temperature of the rich exhaust gas being greater than a threshold temperature.

2. The system of claim 1 , wherein the air injector is positioned to inject air directly into a portion of the exhaust passage downstream of an exhaust gas sensor arranged between the first and second lean NO x traps, wherein a rate of the air flow of the air injector is based on a difference between a lambda value of an exhaust gas and a stoichiometric lambda value to block the rich exhaust gas from passing through the second lean NO x trap during the regeneration of the first lean NO x trap.

3. The system of claim 1 , wherein the instructions further enable the controller to adjust the air flow from the air injector and adjust an engine air/fuel ratio to a rich air/fuel ratio in response to the second lean NO x trap requesting a desulfation, wherein the air flow is adjusted to lean an exhaust gas air/fuel ratio exiting the second lean NO x trap.

4. The system of claim 3 , wherein the air flow increases as a load of the second lean NO x trap decreases during the regeneration of the second lean NO x trap when the temperature of the rich exhaust gas is greater than the threshold temperature.

5. The system of claim 1 , wherein the second lean NO x trap is in a far-underbody position.

6. The system of claim 1 , wherein the air injector is the only air injector of the exhaust passage, and wherein another air injector is not arranged between the second lean NO x trap and the selective catalytic reduction device.

7. The system of claim 1 , wherein a rate of the air flow during the regeneration of the second lean NOx trap adjusts the rich exhaust gas to be less rich upstream of the second lean NO x trap, wherein the exhaust gas downstream of the second lean NO x trap device is lean.

8. An engine system comprising:
an exhaust passage fluidly coupled to an engine, the exhaust passage housing a first LNT upstream of a second LNT, and a SCR device arranged downstream of the second LNT;
an injector positioned to inject air directly into a portion of the exhaust passage between the first LNT, the second LNT, and an exhaust gas sensor; and
a controller with computer-readable instructions stored on non-transitory memory thereof that when executed enable the controller to:
adjust an engine air/fuel ratio to a rich air/fuel ratio and an air flow rate of the injector in response to a temperature of the second LNT being greater than a threshold temperature, wherein the air flow rate increases as a load of the second LNT decreases.

9. The engine system of claim 8 , wherein the air flow rate is further based on the rich air/fuel ratio, and wherein an air/fuel ratio of exhaust gas between the injector and the second LNT is adjusted to equal to a lean air/fuel ratio via an air injection during a regeneration of the first LNT.

10. The engine system of claim 8 , wherein the instructions further enable the controller to adjust the engine air/fuel ratio to the rich air/fuel ratio and the air flow rate of the injector in response to a second LNT regeneration request.

11. The engine system of claim 10 , wherein an air/fuel ratio of exhaust gas flowing to the second LNT is rich but less rich than the engine air/fuel ratio via the air flow rate, and wherein an air/fuel ratio of exhaust gas downstream of the second LNT is a lean air/fuel ratio.

12. The engine system of claim 11 , wherein the air/fuel ratio of exhaust gas flowing to the second LNT is increased toward a stoichiometric air/fuel ratio as the load of the second LNT decreases, and wherein the air/fuel ratio to the selective catalytic device remains equal to the lean air/fuel ratio.

13. The engine system of claim 8 , wherein the instructions further enable the controller to adjust the air flow rate to zero in response to the temperature of the second LNT being greater than or equal to a threshold DeSO x temperature, wherein the threshold DeSO x temperature is less than the threshold temperature.

14. The engine system of claim 8 , wherein the instructions further enable the controller to adjust the air flow rate in response a temperature of the second LNT exceeding the threshold temperature in response to an air/fuel ratio sensed between the first LNT and the second LNT being less than 1, wherein the air flow rate is based on a difference between the temperature of the second LNT and the threshold temperature, wherein as the difference increases the air flow rate increases.

15. The engine system of claim 14 , wherein the air/flow rate is reduced to zero in response to the temperature of the second LNT falling below the threshold temperature.

16. A method comprising:
injecting air from an injector of an air supply device positioned to inject between a first LNT and a second LNT in response to the first LNT being desulfated; wherein
the injecting air from the injector is in response to a temperature of the second LNT being less than a threshold DeSO x temperature; and
injecting air from the injector in response to the temperature of the second LNT being greater than an upper threshold temperature, which is greater than the threshold DeSO x temperature, wherein an air supply rate is based on a difference between the temperature of the second LNT and the upper threshold temperature.

17. The method of claim 16 , wherein injecting air further comprises adjusting the air supply rate of the injector based on an air/fuel ratio of exhaust gas between the first LNT and the second LNT, and wherein the air supply rate increases as a difference between the air/fuel ratio and a stoichiometric air/fuel ratio increases.

18. The method of claim 16 , further comprising deactivating the injector to no longer inject air in response to the temperature of the second LNT being greater than the threshold DeSO x temperature.

Assignees

• Ford Global Tech Llc

Inventors

• Smirnov Evgeny
• Ukropec Robert
• Roemer Dirk
• Armiento Maria
• Harmsen Jan

Classifications

• F01N2900/1602

  Temperature of exhaust gas apparatus · CPC title

• F01N2900/1402

  Exhaust gas composition · CPC title

• Y02T10/40

  Engine management systems · CPC title

• F01N9/00

  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

• F01N11/007

  the diagnostic devices measuring oxygen or air concentration downstream of the exhaust apparatus · CPC title