APPARATUS, SYSTEM, AND METHOD FOR MITIGATING DIESEL EXHAUST FLUID DEPOSITS AND ASSOCIATED CONDITIONS

• US 20110146240A1
• Filed: 12/21/2010
• Published: 06/23/2011
• Est. Priority Date: 12/21/2009
• Status: Active Grant

• Current Assignee: Cummins Incorporated
• Original Assignee: Cummins Incorporated
• Inventors: Lin, Xiao, Wilhelm, Daniel D., Farrell, Lisa, Kern, Robert, Mitchell, Douglas Alan, Evans, April, Owusu, Kwadwo O.
• Granted Patent: US 8,528,319 B2
• Time in Patent Office: Days
• US Class Current: 60/274
• CPC Class Codes: F01N 11/00 Monitoring or diagnostic devices for exhaust-gas treatment apparatus , e.g. for catalytic activity safety, indicating or supervising devices for internal combustion engines F02B77/08; testing of machines G01M13/00
• CPC Class Codes: F01N 13/009 having two or more separate purifying devices arranged in series
• CPC Class Codes: F01N 2550/05 Systems for adding substances into exhaust
• CPC Class Codes: F01N 2610/02 the substance being ammonia or urea
• CPC Class Codes: F01N 2610/1493 Purging the reducing agent out of the conduits or nozzle
• CPC Class Codes: F01N 2900/0422 measuring the elapsed time
• CPC Class Codes: F01N 2900/08 said parameters being related to the engine
• CPC Class Codes: F01N 2900/1602 Temperature of exhaust gas apparatus
• CPC Class Codes: F01N 2900/1606 Particle filter loading or soot amount
• CPC Class Codes: F01N 2900/1621 Catalyst conversion efficiency
• CPC Class Codes: F01N 3/021 by means of filters
• CPC Class Codes: F01N 3/023 using means for regenerating the filters, e.g. by burning trapped particles by electrically controlling the supply of combustible mixture or its constituents only F02D41/0235
• CPC Class Codes: F01N 3/106 Auxiliary oxidation catalysts
• CPC Class Codes: F01N 3/208 Control of selective catalytic reduction [SCR], e.g. dosing of reducing agent
• 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 41/024 to increase temperature of the exhaust gas treating apparatus
• CPC Class Codes: F02D 41/027 to purge or regenerate the exhaust gas treating apparatus
• CPC Class Codes: F02D 41/1441 Plural sensors
• CPC Class Codes: F02D 41/1448 the characteristics being an exhaust gas pressure
• CPC Class Codes: F02D 41/1461 of the exhaust gases emitted by the engine
• CPC Class Codes: F02D 41/1463 : of the exhaust gases downstream of exhaust gas treatment apparatus
• CPC Class Codes: Y02T 10/12 : Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 : Engine management systems

Abstract

According to one embodiment, described herein is an apparatus for mitigating on-board diagnostic (OBD) faults generated by an OBD system of an internal combustion engine (ICE) system having a selective catalytic reduction system with a diesel exhaust fluid (DEF) decomposition tube. The apparatus includes a fault mitigation module that is configured to monitor at least one OBD signal of the OBD system and issue a request for regenerating the DEF decomposition tube when a value of the at least one OBD signal reaches a predetermined regeneration threshold corresponding with the at least one OBD signal. The regeneration threshold is reachable prior to an OBD fault threshold corresponding with the at least one OBD signal. The apparatus also includes a regeneration module that is configured to regenerate the DEF decomposition tube according to the issued request.

Claims

1. An apparatus for mitigating on-board diagnostic (OBD) faults generated by an OBD system of an internal combustion engine (ICE) system having a selective catalytic reduction system with a diesel exhaust fluid (DEF) decomposition tube, comprising:

a fault mitigation module configured to monitor at least one OBD signal of the OBD system and issue a request for regenerating the DEF decomposition tube when a value of the at least one OBD signal reaches a predetermined regeneration threshold corresponding with the at least one OBD signal, the regeneration threshold being reachable prior to an OBD fault threshold corresponding with the at least one OBD signal; and

a regeneration module configured to regenerate the DEF decomposition tube according to the issued request.

2. The apparatus of claim 1, further comprising a system override module configured to alert a user of user actions preventing the initiation of a requested regeneration event and implement measures for mitigating consequences of the user actions if the user does not cease the user actions within a predetermined time period.

3. The apparatus of claim 2, further comprising a diagnostic interrupt module configured to suspend monitoring of the at least one OBD signal in response to the issuance of a request for regenerating the DEF decomposition tube, wherein the measures for mitigating consequences of the user actions comprise overriding the suspension of the monitoring of the at least one OBD signal to re-enable the monitoring of the at least one OBD signal.

4. The apparatus of claim 2, wherein the measures for mitigating consequences of the user actions comprise torque derating of the ICE system.

5. The apparatus of claim 2, wherein the predetermined time period is based on an estimate of the deposition rate of DEF deposits within the DEF decomposition tube.

6. The apparatus of claim 1, further comprising a regeneration frequency module configured to monitor the period of time between a previous exhaust aftertreatment system regeneration event and the request for regenerating the DEF decomposition tube, wherein the regeneration frequency module delays an initiation of the requested regeneration of the DEF decomposition tube if the period of time is less than a time threshold.

7. The apparatus of claim 1, further comprising a diagnostic interrupt module configured to suspend monitoring of the at least one OBD signal in response to the issuance of a request for regenerating the DEF decomposition tube.

8. The apparatus of claim 7, wherein the diagnostic interrupt module is configured to resume monitoring of the at least one OBD signal after regeneration of the DEF decomposition tube is complete.

9. The apparatus of claim 1, further comprising a system override module configured to limit a normal injection rate of DEF into the DEF decomposition tube during active DEF decomposition tube regeneration.

10. The apparatus of claim 9, wherein the system override module limits the normal injection rate of DEF by a determined amount based on a maximum DEF injection rate for DEF decomposition, a minimum DEF injection rate for cooling a DEF injector tip, a DEF injection rate corresponding to a minimum desired ammonia-to-NOx ratio at an inlet of a selective catalytic reduction catalyst of the selective catalytic reduction system, and the normal injection rate of DEF.

11. The apparatus of claim 10, wherein the limited injection rate of DEF is the lesser of:

(1) the greater of the maximum DEF injection rate for DEF decomposition, the minimum DEF injection rate for cooling a DEF injector tip, and the DEF injection rate corresponding to the minimum desired ammonia-to-NOx ratio; and

(2) the normal injection rate of DEF.

12. The apparatus of claim 1, wherein the at least one OBD signal comprises at least one of a first OBD signal corresponding with a NO_x conversion efficiency of the selective catalytic reduction system and a second OBD signal corresponding with a particulate matter filter outlet high pressure.

13. A system for mitigating on-board diagnostic (OBD) faults generated by an OBD system of an internal combustion engine (ICE) system and caused by solid diesel exhaust fluid (DEF) deposits, comprising:

a selective catalytic reduction (SCR) system comprising a DEF injector and DEF decomposition tube, the DEF injector configured to inject DEF into the DEF decomposition tube; and

a controller comprising;

a diagnostic fault module configured to monitor a plurality of OBD signals of the OBD system and set a diagnostic fault when a monitored OBD signal reaches a fault threshold corresponding with the monitored OBD signal;

a fault mitigation module configured to monitor at least one OBD signal of the plurality of OBD signals that is susceptible to solid DEF deposits within the decomposition tube, the fault mitigation module being configured to request regeneration of the DEF decomposition tube when the at least one monitored OBD signal susceptible to solid DEF deposits within the decomposition tube reaches a corresponding regeneration threshold, wherein the regeneration threshold is set to be reached before the fault threshold corresponding with the at least one monitored susceptible OBD signal.

14. The system of claim 13, wherein the at least one susceptible OBD signal comprises a NO_x conversion efficiency OBD signal.

15. The system of claim 13, wherein the system comprises a particulate matter filter in exhaust providing communication with the SCR system, and wherein the at least one susceptible OBD signal comprises a particulate matter filter outlet high pressure OBD signal based at least partially on input from a particulate matter filter outlet exhaust pressure sensor.

16. The system of claim 13, wherein the controller comprises an override module configured to limit the rate at which DEF is injected into the DEF decomposition tube by the DEF injector during an active regeneration of the DEF decomposition tube.

17. The system of claim 13, further comprising an oxidation catalyst upstream of the SCR system, wherein the DEF decomposition tube is positioned between an SCR catalyst of the SCR system and the oxidation catalyst, and wherein control of the regeneration of the DEF decomposition tube is based on an oxidation catalyst outlet temperature.

18. A method for mitigating on-board diagnostic (OBD) faults in an internal combustion engine (ICE) system having a selective catalytic reduction system with a diesel exhaust fluid (DEF) decomposition tube, the method comprising;

monitoring a plurality of OBD signals;

setting a diagnostic fault when one of the plurality of OBD signal reaches a corresponding fault threshold;

monitoring at least one OBD signal of the plurality of OBD signals that is susceptible to solid DEF deposits within the decomposition tube;

requesting regeneration of the DEF decomposition tube when the at least one OBD signal susceptible to solid DEF deposits within the decomposition tube reaches a corresponding regeneration threshold, the regeneration threshold being reachable before the fault threshold corresponding with the at least one susceptible OBD signal;

regenerating the DEF decomposition tube according to the regeneration request; and

suspending monitoring of the at least one susceptible OBD signal during regeneration of the DEF decomposition tube.

19. The method of claim 18, wherein the at least one susceptible OBD signal comprises a NO_x conversion efficiency OBD signal associated with the selective catalytic reduction system, and wherein the regeneration threshold of the NO_x conversion efficiency OBD signal is higher than the fault threshold of the NO_x conversion efficiency OBD signal.

20. The method of claim 18, wherein the ICE system comprises a particulate matter filter, wherein the at least one susceptible OBD signal comprises a particulate matter filter outlet high pressure OBD signal, and wherein the regeneration threshold of the particulate matter filter outlet high pressure OBD signal is lower than the fault threshold of the particulate matter filter outlet high pressure OBD signal.