# US 8,783,017 B2 · System, method, and apparatus to engage alternate reductant in a NOx reduction system

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- Number: US 8,783,017 B2
- Document ID: US8783017B2
- Status: Granted
- Kind: B2
- Application number: 13/045,194
- Filed: 2011-03-10
- Published: 2012-02-02
- Granted: 2014-07-22
- Earliest claimed: 2010-03-11
- Assignees: Cummins Inc.
- Applicants: Aleksey Yezerets; Zheng Liu; Neal W. Currier; J. Stephen Wills
- Inventors: Aleksey Yezerets; Zheng Liu; Neal W. Currier; J. Stephen Wills
- Web page: https://patentgrep.com/patent/US8783017B2

## CPC

- F01N 3/208: {Control of selective catalytic reduction [SCR], e.g. by adjusting the dosing of reducing agent}
- F02D 41/0275: {the exhaust gas treating apparatus being a NOx trap or adsorbent}
- F02D 41/405: {with post injections}
- F01N 2560/06: the means being a temperature sensor
- F01N 2610/02: the substance being ammonia or urea
- F01N 2610/03: the substance being hydrocarbons, e.g. engine fuel
- F02D 41/1446: {the characteristics being exhaust temperatures}
- 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

An exhaust aftertreatment process including providing a selective catalytic reduction (SCR) catalyst disposed in an exhaust stream of an internal combustion engine; determining that a temperature of the exhaust stream is not within an NH3 based SCR range; and providing an amount of unburned hydrocarbon (UHC) to the SCR catalyst in response to the temperature of the exhaust stream not being within an NH3 based SCR range.

## Claims

### Claim 1

A method, comprising:
providing a selective catalytic reduction (SCR) catalyst disposed in an exhaust stream of an internal combustion engine;
determining that a temperature of the exhaust stream is not within an ammonia (NH3) based SCR range when the temperature of the exhaust stream is below a lower temperature threshold and when the temperature of the exhaust stream is above an upper temperature threshold; and
providing an amount of unburned hydrocarbon (UHC) to the SCR catalyst in response to determining the temperature of the exhaust stream is not within the ammonia (NH3)based SCR range while reducing an amount of urea injected into the exhaust stream in response to the amount of UHC provided.

### Claim 2 (depends on 1)

The method of claim 1, wherein the lower temperature threshold is below 200° C.

### Claim 3 (depends on 1)

The method of claim 1, wherein the upper temperature threshold is above 250° C.

### Claim 4 (depends on 1)

The method of claim 1, wherein the upper temperature threshold is above 300° C.

### Claim 5 (depends on 1)

The method of claim 1, wherein the upper temperature threshold is above 400° C.

### Claim 6 (depends on 1)

The method of claim 1, wherein determining that the temperature of the exhaust stream is not within the NH3 based SCR range comprises determining that a urea hydrolysis effectiveness is below a hydrolysis threshold value.

### Claim 7 (depends on 1)

The method of claim 1, wherein determining that the temperature of the exhaust stream is not within the NH3 based SCR range comprises determining that an NH3 oxidation effectiveness is greater than an oxidation threshold value.

### Claim 8 (depends on 1)

The method of claim 1, wherein providing an amount of unburned hydrocarbon (UHC) to the SCR catalyst comprises performing a UHC addition operation selected from the operations:
injecting an amount of fuel into a cylinder of the engine at a very late timing such that the injected amount of fuel does not combust in the cylinder; and
injecting an amount of fuel directly into the exhaust stream.

### Claim 9

A system, comprising:
a selective catalytic reduction (SCR) catalyst disposed in an exhaust stream of an internal combustion engine; and
a controller structured to:
determine that a temperature of the exhaust stream is not within an ammonia (NH3) based SCR range in response to the temperature of the exhaust stream being below a lower temperature threshold and in response to the temperature of the exhaust stream being above an upper temperature threshold; and
provide an unburned hydrocarbon (UHC) addition command for the SCR catalyst in response to determining the temperature of the exhaust stream is not within the NH3 based SCR range while reducing an amount of urea injected into the exhaust stream in response to the amount of UHC provided.

### Claim 10 (depends on 9)

The system of claim 9, wherein the controller is further structured to determine that a temperature of the exhaust stream is not within the NH3 based SCR range by determining that a urea hydrolysis effectiveness is below a hydrolysis threshold value.

### Claim 11 (depends on 9)

The system of claim 9, wherein the controller is further structured to determine that a temperature of the exhaust stream is not within the NH3 based SCR range by determining that an NH3 oxidation effectiveness is greater than an oxidation threshold value.

### Claim 12 (depends on 9)

The system of claim 9, further comprising a fuel injector operationally coupled to the exhaust stream at a position upstream of the SCR catalyst, wherein the fuel injector is responsive to the UHC addition command.

### Claim 13 (depends on 9)

The system of claim 9, wherein the engine comprises a common rail fuel system capable of injecting a very late post injection fuel, wherein the very late post injection fuel does not combust in a cylinder of the engine, and wherein the common rail fuel system is responsive to the UHC addition command.

### Claim 14 (depends on 9)

The system of claim 9, wherein the SCR catalyst comprises a zeolite based catalyst.

### Claim 15

An apparatus, comprising:
a selective catalytic reduction (SCR) catalyst disposed in an exhaust stream of an engine;
an off-nominal temperature module structured to determine an off nominal temperature indicator in response to determining that a temperature of the exhaust stream is not within an ammonia (NH3)based selective catalytic reduction (SCR) range when the temperature of the exhaust stream is below a lower temperature threshold and when the temperature of the exhaust stream is above an upper temperature threshold; and
a secondary NOx reduction module structured to provide an unburned hydrocarbon (UHC) addition command for the SCR catalyst in response to the off nominal temperature indicator and to provide a urea reduction command for the SCR catalyst in response to the UHC addition command.

### Claim 16 (depends on 15)

The apparatus of claim 15, wherein the lower temperature threshold is below 200° C.

### Claim 17 (depends on 15)

The apparatus of claim 15, wherein the upper temperature threshold is above 250° C.

### Claim 18 (depends on 15)

The apparatus of claim 15, wherein the upper temperature threshold is above 300° C.

### Claim 19 (depends on 15)

The apparatus of claim 15, wherein the upper temperature threshold is above 400° C.

### Claim 20 (depends on 15)

The apparatus of claim 15, wherein the off-nominal temperature module is further structured to determine that the temperature of the exhaust stream is not within the NH3 based SCR range by determining that a urea hydrolysis effectiveness is below a hydrolysis threshold value.

### Claim 21 (depends on 15)

The apparatus of claim 15, wherein the off-nominal temperature module is further structured to determine that the temperature of the exhaust stream is not within the NH3 based SCR range by determining that an NH3 oxidation effectiveness is greater than an oxidation threshold value.