Methods and systems to control exhaust gas recirculation

Patent metadata

Field	Value
Publication number	US-9863344-B2
Application number	US-201514745868-A
Country	US
Kind code	B2
Filing date	Jun 22, 2015
Priority date	Jun 22, 2015
Publication date	Jan 9, 2018
Grant date	Jan 9, 2018

Abstract

A system includes an engine comprising an EGR valve that recirculates a portion of exhaust gas, a data repository that stores a first look up and one or more engine operational parameters, an engine control unit operationally coupled to the engine and the data repository, wherein the engine control unit is configured to: determine a desired EGR flow rate reference of the portion of the exhaust gas based on the one or more engine operational parameters and the first look up table, determine a current estimated EGR flow rate based on the one or more engine operational parameters, determine a designated corrected EGR flow rate reference based on the desired EGR flow rate reference and a delta EGR flow rate, determine EGR flow rate error, and determine a percentage opening of the EGR valve based at least on the EGR flow rate error.

First claim

The invention claimed is:

1. A system, comprising:
an engine comprising an exhaust-gas-recirculation (EGR) valve that recirculates a portion of a exhaust gas, generated by the engine, within the engine;
a data repository that stores a first look up table and one or more engine operational parameters;
an engine control unit operationally coupled to the engine and the data repository, wherein the engine control unit is configured to:
determine a desired EGR flow rate reference of the portion of the exhaust gas based on the one or more engine operational parameters and the first look up table;
determine a current estimated EGR flow rate based on the one or more engine operational parameters;
determine a delta EGR flow rate based on a current amount of NOx emissions and a desired amount of NOx emissions;
determine a designated corrected EGR flow rate reference based on the desired EGR flow rate reference and the delta EGR flow rate, wherein the delta EGR flow rate is used to correct the desired EGR flow rate reference to account for the current amount of NOx emissions and the desired amount of NOx emissions;
determine EGR flow rate error based on the current estimated EGR flow rate and the designated corrected EGR flow rate reference;
determine a percentage opening of the EGR valve based at least on the EGR flow rate error; and
control the EGR valve to achieve the percentage opening of the EGR valve.

2. The system of claim 1 , wherein the first look up table comprises a table or a function that relates the one or more engine operational parameters to the desired EGR flow rate reference, however does not take into account the current NOx emissions from the engine.

3. The system of claim 1 , wherein the engine control unit is configured to determine the desired EGR flow rate reference by mapping the one or more engine operational parameters to the desired EGR flow rate reference using the first look up table.

4. The system of claim 1 , wherein the engine control unit is configured to determine the designated corrected EGR flow rate reference by subtracting the delta EGR flow rate from the desired EGR flow rate reference.

5. The system of claim 1 , wherein the data repository further stores a second look up table and an IMAP-look-up-table.

6. The system of claim 5 , wherein the engine control unit is further configured to:
receive the current amount of NOx emissions;
determine the desired amount of NOx emissions from the engine based on the second look up table and the one or more engine operational parameters;
determine a NOx error based on the current amount of NOx emissions and the desired amount of NOx emissions; and
determine the delta EGR flow rate based on the NOx error.

7. The system of claim 6 , wherein the second look up table comprises a function that relates the one or more engine operational parameters to the desired amount of NOx emissions from the engine.

8. The system of claim 6 , wherein the engine control unit is configured to determine the desired amount of NOx emissions by mapping the one or more engine operational parameters to the desired amount of NOx emissions using the second look up table.

9. The system of claim 1 , wherein the engine control unit is configured to control the EGR valve to achieve the percentage opening of the EGR valve resulting in the desired amount of NOx emissions and a desired amount of formation of particulate matter.

10. A system, comprising:
an engine comprising:
an exhaust-gas-recirculation (EGR) valve that recirculates a portion of exhaust gas, generated by the engine, within the engine;
an inlet manifold comprising air-fuel-exhaust mixture characterized by a pressure (IMAP);

a data repository that stores an IMAP-look-up-table and one or more engine operational parameters;
an engine control unit operationally coupled to the engine and the data repository, wherein the engine control unit is configured to:
determine a desired IMAP reference based on the one or more engine operational parameters and the IMAP look up table;
determine a current estimated IMAP in the inlet manifold based on the one or more engine operational parameters;
determine a delta IMAP based on a current amount of NOx emissions and a desired amount of NOx emissions;
determine a designated corrected IMAP reference based on the desired IMAP reference and the delta IMAP, wherein the delta IMAP is used to correct the desired IMAP reference to account for the current amount of NOx emissions and the desired amount of NOx emissions;
determine an IMAP error based on the current estimated IMAP and the designated corrected IMAP reference;
determine a percentage opening of the EGR valve based at least on the IMAP error; and
control the EGR valve to achieve the percentage opening of the EGR valve.

11. The system of claim 10 , wherein the IMAP-look-up-table comprises a table or a function that relates the one or more engine operational parameters to the desired IMAP reference.

12. The system of claim 10 , wherein the engine control unit is configured to determine the desired IMAP reference by mapping the one or more engine operational parameters to the desired IMAP reference using the IMAP-look-up-table.

13. The system of claim 10 , wherein the engine control unit is configured to determine the designated corrected IMAP reference by subtracting the delta IMAP from the desired IMAP reference.

14. The system of claim 10 , wherein the data repository further stores a second look up table comprising a function or a table that relates the one or more engine operational parameters to a desired amount of NOx emissions from the engine.

15. The system of claim 14 , wherein the engine control unit is further configured to:
receive the current amount of NOx emissions;
determine the desired amount of NOx emissions from the engine based on the second look up table and the one or more engine operational parameters;
determine a NOx error based on the current amount of NOx emissions and the desired amount of NOx emissions; and
determine the delta IMAP based on the NOx error.

16. The system of claim 15 , wherein the engine control unit is configured to determine the desired amount of NOx emissions by mapping the one or more engine operational parameters to the desired amount of NOx emissions using the second look up table.

17. The system of claim 1 , wherein the engine control unit is further configured to control the EGR valve to achieve the percentage opening of the EGR valve resulting in the desired amount of NOx emissions and a desired amount of formation of particulate matter.

18. A system, comprising:
an engine comprising:
an exhaust-gas-recirculation (EGR) valve that recirculates a portion of exhaust gas, generated by the engine, within the engine;
an inlet manifold comprising air-fuel-exhaust mixture characterized by a pressure (IMAP);

a data repository that stores a first look up table, an IMAP-look-up-table and one or more engine operational parameters;
an engine control unit operationally coupled to the engine and the data repository, wherein the engine control unit is configured to:
select between an IMAP process and an EGR process based on one or more factors;
determine a percentage opening of the EGR valve by executing the IMAP process or the EGR process after selection of the IMAP process or the EGR process,
control the EGR valve to achieve the percentage opening of the EGR valve, wherein the IMAP process comprises:
determining a desired IMAP reference based on the one or more engine operational parameters a

Assignees

• Gen Electric

Inventors

• Deb Dipankar
• Srinivasan Prashant
• Satria Medy
• Devarakonda Maruthi Narasinga Rao
• Bhatt Dhruval

Classifications

• F02D41/0052

  Feedback control of engine parameters, e.g. for control of air/fuel ratio or intake air amount · CPC title

• F02D21/08

  the other gas being the exhaust gas of engine · CPC title

• F02D2021/083

  controlling exhaust gas recirculation electronically · CPC title

• F02D41/0072

  Estimating, calculating or determining the EGR rate, amount or flow (sensors in EGR systems F02M26/45) · CPC title

• F02D41/0077 Primary

  Control of the EGR valve or actuator, e.g. duty cycle, closed loop control of position (EGR valve position sensor F02M26/48) · CPC title