Selective catalytic reduction dosing control

• US 10,443,471 B2
• Filed: 05/04/2017
• Issued: 10/15/2019
• Est. Priority Date: 05/04/2017
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Funk, Sarah, Sisco, Eric M., Deleon, Jose
• Primary Examiner(s): Bradley, Audrey K
• Assistant Examiner(s): Ayala Delgado, Anthony
• Application Number:
  US15/586,801
• Publication Number:
  US 20180320572A1
• Time in Patent Office: 894 Days
• CPC Class Codes: F01N 11/007 the diagnostic devices measuring oxygen or air concentration downstream of the exhaust apparatus
• CPC Class Codes: F01N 2610/02 the substance being ammonia or urea
• CPC Class Codes: F01N 2610/146 Control thereof, e.g. control of injectors or injection valves
• CPC Class Codes: F01N 2900/0402 using adaptive learning
• CPC Class Codes: F01N 2900/08 said parameters being related to the engine
• CPC Class Codes: F01N 2900/1402 Exhaust gas composition
• CPC Class Codes: F01N 2900/1821 Injector parameters
• CPC Class Codes: F01N 3/208 Control of selective catalytic reduction [SCR], e.g. dosing of reducing agent
• CPC Class Codes: F01N 9/005 using models instead of sensors to determine operating characteristics of exhaust systems, e.g. calculating catalyst temperature instead of measuring it directly
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

Technical solutions are described for an emissions control system for a motor vehicle including an internal combustion engine. The emissions control system includes a reductant injector device, a selective catalytic reduction (SCR) device, and a controller. The controller determines a reductant energizing time for the reductant injector device based on one or more operating conditions of the SCR device. The controller further computes a diagnostic adaptation factor for the reductant energizing time based on an on-board diagnostic signal. The controller further inputs an amount of reductant into the SCR device by adjusting a reductant energizing time of the reductant injector device according to the diagnostic adaptation factor.

Claims

1. An emissions control system for treating exhaust gas in a motor vehicle including an internal combustion engine, the emissions control system comprising:

a reductant injector device;

a selective catalytic reduction (SCR) device; and

a controller configured to;

determine a reductant energizing time for the reductant injector device based on one or more operating conditions of the SCR device;

compute a diagnostic adaptation factor for the reductant energizing time based on an on-board diagnostic signal;

changing a target NH₃ storage level of the SCR device to the diagnostic adaptation factor; and

input an amount of reductant into the SCR device by adjusting a reductant energizing time of the reductant injector device to cause the SCR device to store an amount of NH₃ substantially equal to the target NH₃ storage level;

wherein computing the diagnostic adaptation factor comprises;

determining a diagnostic factor based on the on-board diagnostic signal;

comparing the diagnostic factor with a predetermined threshold; and

in response to the diagnostic factor being greater than the predetermined threshold, computing the diagnostic adaptation factor as a maximum of the diagnostic factor and a predetermined long-term adaptation factor, and

in response to the diagnostic factor not being greater than the predetermined threshold, computing the diagnostic adaptation factor as a minimum of the diagnostic factor and the predetermined long-term adaptation factor.

2. The emissions control system of claim 1, wherein the controller inputs the amount of reductant into the SCR device by instructing the reductant injector device.

3. The emissions control system of claim 1, wherein the diagnostic adaptation factor is further based on a difference between a predicted NOx value in exhaust gases and measured NOx value in the exhaust gas.

4. The emissions control system of claim 3, wherein the predicted NOx value is based on a chemical model of the SCR device.

5. The emissions control system of claim 1, wherein the on-board diagnostic signal comprises a plurality of diagnostic signals and the diagnostic adaptation factor is computed as a function of the plurality of diagnostic signals.

6. The emissions control system of claim 1, wherein the diagnostic adaptation factor is computed based on an exponentially weighted moving average of the on-board diagnostic signal.

7. The emissions control system of claim 1, wherein the controller is further configured to use the diagnostic adaptation factor as the predetermined long-term adaptation factor.

8. An exhaust system for treating exhaust gas emitted by an internal combustion engine, configured to perform a selective catalytic reduction (SCR) of exhaust gas, the exhaust system comprising:

a controller configured to;

compute a diagnostic adaptation factor for an SCR device of the exhaust system based on an on-board diagnostic signal; and

input an amount of a reductant into the SCR device by configuring the exhaust system according to the diagnostic adaptation factor, wherein configuring the exhaust system comprises using the diagnostic adaptation factor as a target NH₃ storage level of the SCR device;

wherein computing the diagnostic adaptation factor comprises;

determining a diagnostic factor based on the on-board diagnostic signal;

comparing the diagnostic factor with a predetermined threshold; and

in response to the diagnostic factor being greater than the predetermined threshold, computing the diagnostic adaptation factor as a maximum of the diagnostic factor and a predetermined long-term adaptation factor, and

in response to the diagnostic factor not being greater than the predetermined threshold, computing the diagnostic adaptation factor as a minimum of the diagnostic factor and the predetermined long-term adaptation factor.

9. The exhaust system of claim 8, wherein the diagnostic adaptation factor is based on a difference between a predicted NOx value in the exhaust gas and measured NOx value in the exhaust gas.

10. The exhaust system of claim 8, wherein configuring the exhaust system comprises scaling a reductant energizing time of a reductant injector of the exhaust system using the diagnostic adaptation factor.

11. The exhaust system of claim 8, wherein the diagnostic adaptation factor is computed based on an exponentially weighted moving average of the on-board diagnostic signal.

12. The exhaust system of claim 8, wherein the controller is further configured to set the diagnostic adaptation factor as the predetermined long-term adaptation factor.

13. A computer-implemented method for controlling a selective catalytic reduction (SCR) device of an exhaust system of an internal combustion engine, the method comprising:

computing a diagnostic adaptation factor for an SCR device of the exhaust system based on an on-board diagnostic signal; and

inputting an amount of reductant into the SCR device by configuring the exhaust system according to the diagnostic adaptation factor, wherein configuring the exhaust system comprises using the diagnostic adaptation factor as a NH₃ set-point of the SCR device;

wherein computing the diagnostic adaptation factor further comprises;

determining a diagnostic factor based on the on-board diagnostic signal;

comparing the diagnostic factor with a predetermined threshold; and

in response to the diagnostic factor being greater than the predetermined threshold, computing the diagnostic adaptation factor as a maximum of the diagnostic factor and a predetermined long-term adaptation factor, and

in response to the diagnostic factor not being greater than the predetermined threshold, computing the diagnostic adaptation factor as a minimum of the diagnostic factor and the predetermined long-term adaptation factor.

14. The method of claim 13, configuring the exhaust system comprises scaling a reductant energizing time of a reductant injector of the exhaust system using the diagnostic adaptation factor.

15. The method of claim 13, wherein the diagnostic adaptation factor is based on a difference between a predicted NOx value in exhaust gas in the exhaust system and measured NOx value in the exhaust gas, and the diagnostic adaptation factor is computed based on an exponentially weighted moving average of the on-board diagnostic signal.