# US 2014/0150409 A1 · Method, Apparatus, and System To Control Selective Catalytic Reduction (SCR) Catalyst Ammonia Slip During High Temperature Transitions

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- Number: US 2014/0150409 A1
- Document ID: US20140150409A1
- Status: Published application
- Kind: A1
- Application number: 13/837,492
- Filed: 2013-03-15
- Published: 2014-06-05
- Earliest claimed: 2012-11-30
- Assignees: Corning Incorporated
- Applicants: Corning Incorporated
- Inventors: Sam George; Achim Karl-Erich Heibel
- Web page: https://patentgrep.com/patent/US20140150409A1

## CPC

- F01N 3/208: {Control of selective catalytic reduction [SCR], e.g. by adjusting the dosing of reducing agent}
- F01N 9/00: 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)
- F01N 2430/00: Influencing exhaust purification, e.g. starting of catalytic reaction, filter regeneration, or the like, by controlling engine operating characteristics
- F01N 2610/02: the substance being ammonia or urea
- F01N 2900/08: said parameters being related to the engine
- F01N 2900/1616: NH3-slip from catalyst
- F01N 2900/1812: Flow rate
- 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)
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

Method, apparatus, and system to control ammonia slip in a selective catalytic reduction (SCR) system. The method includes detecting an engine operation transition event, increasing NOx to the SCR catalyst, and decreasing a reductant dose. The system includes a controller to receive an engine transition signal, anticipate a temperature transition at the SCR catalyst in response to the engine transition signal, and cause a NOx increase in the exhaust gas stream to the SCR catalyst and a decrease of reductant to the SCR catalyst coinciding with the temperature transition at the SCR catalyst. The apparatus includes a NOx increase module to cause the NOx increase in the exhaust gas stream to the SCR catalyst in response to the engine transition signal. The apparatus also includes a reductant shut-off module configured to cause the reductant addition to the exhaust gas stream to turn off in response to the engine transition signal.

## Claims

### Claim 1

A method to control ammonia slip in a selective catalytic reduction (SCR) system, the method comprising:
detecting an engine operation transition event;
increasing NOx concentration in an engine exhaust gas stream; and
decreasing a reductant dose to the exhaust gas stream.

### Claim 2 (depends on 1)

The method of claim 1, wherein the transition event comprises a high temperature event that produces a high temperature in the exhaust.

### Claim 3 (depends on 1)

The method of claim 1, wherein the transition event comprises at least one of an increased fuel flow, a change in fuel delivery pressure to the engine, an engine fuel injection timing change, a change in engine rotations per minute (rpm), and a change in engine torque.

### Claim 4 (depends on 1)

The method of claim 1, wherein detecting comprises receiving a signal indicating at least one of an increased fuel flow, a change in fuel delivery pressure to the engine, an engine fuel injection timing change, a change in engine rotations per minute (rpm), and a change in engine torque.

### Claim 5 (depends on 1)

The method of claim 1, further comprising
delaying increasing NOx for a first time period after detecting the engine transition event; and
delaying turning off the reductant dose for a second time period after detecting the engine transition event.

### Claim 6 (depends on 5)

The method of claim 5, wherein
the first time delay is greater than about 1 second; and
the second time delay is greater than about 1 second.

### Claim 7 (depends on 1)

The method of claim 1, wherein increasing NOx comprises adjusting exhaust gas recirculation in the engine.

### Claim 8 (depends on 1)

The method of claim 1, wherein increasing NOx comprises adjusting fuel injection timing.

### Claim 9 (depends on 1)

The method of claim 1 further comprising:
returning NOx concentration in the engine exhaust gas stream to a regular engine operating level; and
resuming the reductant dose to the SCR catalyst.

### Claim 10 (depends on 9)

The method of claim 9, wherein resuming reductant dose to the SCR catalyst comprises injecting sufficient reductant to cause ammonia adsorption on the SCR catalyst.

### Claim 11 (depends on 9)

The method of claim 9, wherein
returning NOx concentration in the engine exhaust gas stream to the regular engine operating level comprises delaying a first time duration after increasing NOx concentration; and
resuming the reductant dose to the SCR catalyst comprises delaying a second time duration after turning off the reductant dose.

### Claim 12 (depends on 11)

The method of claim 11, wherein
the first time duration is greater than about 1 second; and
the second time duration is greater than about 1 second.

### Claim 13

An apparatus configured to control a selective catalytic reduction (SCR) system of an internal combustion engine system, comprising:
a NOx increase module configured to cause a NOx concentration increase in an engine exhaust gas stream in response to an engine transition signal; and
a reductant control module configured to cause a reductant addition decrease in the engine exhaust gas stream in response to the engine transition signal.

### Claim 14 (depends on 13)

The apparatus of claim 13, further comprising a transition sensor module configured to detect an engine transition event and generate an engine transition signal in response to the detection.

### Claim 15 (depends on 14)

The apparatus of claim 14, wherein the transition sensor module is configured to detect a high temperature event that produces a high temperature in the exhaust as the engine transition event and generate the engine transition signal in response to the detection.

### Claim 16 (depends on 14)

The apparatus of claim 14, wherein the transition sensor module is configured to detect one of an increased fuel flow to the engine, an injection timing advance, an increase in engine rotations per minute (rpm), and an increase in engine torque as the engine transition event and generate the engine transition signal in response to the detection.

### Claim 17 (depends on 13)

The apparatus of claim 13, wherein the NOx increase module is configured to cause adjustment of at least one of an exhaust gas recirculation (EGR) valve, an engine fuel injection timing, intake air pressure, and fuel delivery pressure to the engine.

### Claim 18 (depends on 13)

The apparatus of claim 13, wherein the NOx increase module is configured to cause a first delay period in response to the engine transition signal before causing the NOx increase; and
the reductant control module is configured to cause a second delay period in response to the engine transition signal before causing the reductant turn off signal.

### Claim 19 (depends on 13)

The apparatus of claim 13, wherein the NOx increase module is configured to cause a return NOx level to a regular engine operating level after a first time duration; and
the reductant control module is configured to cause a resumption of the reductant dose after a second time duration.

### Claim 20

A selective catalytic reduction (SCR) system of an internal combustion engine, the system comprising:
an internal combustion engine configured to produce an exhaust gas stream;
a selective catalytic reduction (SCR) catalyst to receive the exhaust gas stream and reduce NOx emissions in the exhaust stream in the presence of a reductant;
a transition sensor module configured to detect an engine transition event and to generate an engine transition signal in response to the detection;
an SCR system controller configured to receive the engine transition signal, and cause a NOx increase in the exhaust gas stream and a decrease of reductant addition to the SCR catalyst in response to the engine transition signal.