# US 8,528,319 B2 · Apparatus, system, and method for mitigating diesel exhaust fluid deposits and associated conditions

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- Number: US 8,528,319 B2
- Document ID: US8528319B2
- Status: Granted
- Kind: B2
- Application number: 12/975,064
- Filed: 2010-12-21
- Published: 2011-06-23
- Granted: 2013-09-10
- Earliest claimed: 2009-12-21
- Assignees: Cummins IP, Inc.
- Applicants: Daniel D. Wilhelm; Kwadwo O. Owusu; April Evans; Xiao Lin; Robert Kern; Douglas Alan Mitchell; Lisa Farrell
- Inventors: Daniel D. Wilhelm; Kwadwo O. Owusu; April Evans; Xiao Lin; Robert Kern; Douglas Alan Mitchell; Lisa Farrell
- Web page: https://patentgrep.com/patent/US8528319B2

## CPC

- F01N 13/009: {having two or more separate purifying devices arranged in series}
- F01N 3/021: by means of filters
- F01N 3/023: using means for regenerating the filters, e.g. by burning trapped particles
- F01N 3/106: {Auxiliary oxidation catalysts}
- F01N 3/208: {Control of selective catalytic reduction [SCR], e.g. by adjusting the dosing of reducing agent}
- F01N 11/00: Monitoring or diagnostic devices for exhaust-gas treatment apparatus
- F02D 41/0235: {in relation with the state of the exhaust gas treating apparatus (control of exhaust gas treating apparatus per se F01N)}
- F02D 41/1441: {Plural sensors}
- F02D 41/1461: {of the exhaust gases emitted by the engine}
- F02D 41/1463: {of the exhaust gases downstream of exhaust gas treatment apparatus}
- F01N 2550/05: Systems for adding substances into exhaust
- F01N 2610/02: the substance being ammonia or urea
- F01N 2610/1493: Purging the reducing agent out of the conduits or nozzle
- F01N 2900/0422: measuring the elapsed time
- F01N 2900/08: said parameters being related to the engine
- F01N 2900/1602: Temperature of exhaust gas apparatus
- F01N 2900/1606: Particle filter loading or soot amount
- F01N 2900/1621: Catalyst conversion efficiency
- F02D 41/024: {to increase temperature of the exhaust gas treating apparatus}
- F02D 41/027: {to purge or regenerate the exhaust gas treating apparatus}
- F02D 41/1448: {the characteristics being an exhaust gas pressure}
- Y02T 10/12: Improving ICE efficiencies
- Y02T 10/40: Engine management systems
- F01N: GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES (arrangements in connection with gas exhaust of propulsion units in vehicles B60K13/00; combustion-air intake silencers specially adapted for, or arranged on, internal-combustion engines F02M35/00; protecting against, or damping, noise in general G10K11/16)
- F02D: CONTROLLING COMBUSTION ENGINES (vehicle fittings, acting on a single sub-unit only, for automatically controlling vehicle speed B60K31/00; conjoint control of vehicle sub-units of different type or different function, road vehicle drive control systems for purposes other than the control of a single sub-unit B60W)
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## 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

### Claim 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, the apparatus comprising an electronic controller with instructions that when executed:
monitors at least one OBD signal of the OBD system and issues 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
regenerates the DEF decomposition tube according to the issued request.

### Claim 2 (depends on 1)

The apparatus of claim 1, wherein the electronic controller further includes instructions that when executed alerts a user of user actions preventing the initiation of a requested regeneration event and implements measures for mitigating consequences of the user actions if the user does not cease the user actions within a predetermined time period.

### Claim 3 (depends on 2)

The apparatus of claim 2, wherein the electronic controller further includes instructions that when executed suspends 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.

### Claim 4 (depends on 2)

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

### Claim 5 (depends on 2)

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.

### Claim 6 (depends on 1)

The apparatus of claim 1, wherein the electronic controller further includes instructions that when executed monitors the period of time between a previous exhaust aftertreatment system regeneration event and the request for regenerating the DEF decomposition tube, and delays an initiation of the requested regeneration of the DEF decomposition tube if the period of time is less than a time threshold.

### Claim 7 (depends on 1)

The apparatus of claim 1, wherein the electronic controller further includes instructions that when executed suspends monitoring of the at least one OBD signal in response to the issuance of a request for regenerating the DEF decomposition tube.

### Claim 8 (depends on 7)

The apparatus of claim 7, wherein the electronic controller further includes instructions that when executed resumes monitoring of the at least one OBD signal after regeneration of the DEF decomposition tube is complete.

### Claim 9 (depends on 1)

The apparatus of claim 1, wherein the electronic controller further includes instructions that when executed limits a normal injection rate of DEF into the DEF decomposition tube during active DEF decomposition tube regeneration.

### Claim 10 (depends on 9)

The apparatus of claim 9, wherein the electronic controller further includes instructions that when executed 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.

### Claim 11 (depends on 10)

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.

### Claim 12 (depends on 1)

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

### Claim 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
an electronic controller with instructions that when executed:
monitors a plurality of OBD signals of the OBD system and sets a diagnostic fault when a monitored OBD signal reaches a fault threshold corresponding with the monitored OBD signal;
monitors at least one OBD signal of the plurality of OBD signals that is susceptible to solid DEF deposits within the decomposition tube; and
requests 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.

### Claim 14 (depends on 13)

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

### Claim 15 (depends on 13)

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.

### Claim 16 (depends on 13)

The system of claim 13, wherein the electronic controller further includes instructions that when executed limits 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.

### Claim 17 (depends on 13)

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.

### Claim 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.

### Claim 19 (depends on 18)

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

### Claim 20 (depends on 18)

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.