METHOD AND SYSTEMS FOR AIRFLOW CONTROL

• US 20170152806A1
• Filed: 12/01/2015
• Published: 06/01/2017
• Est. Priority Date: 12/01/2015
• Status: Active Grant

• Current Assignee: GE Global Sourcing LLC (Westinghouse Air Brake Technologies Corporation)
• Original Assignee: General Electric Company
• Inventors: Henry, Luke Michael, Mischler, James Robert, Zielinski, David
• Granted Patent: US 10,221,798 B2
• Time in Patent Office: Days
• CPC Class Codes: F02D 2041/1412 using a predictive controller
• CPC Class Codes: F02D 2200/0404 Throttle position
• CPC Class Codes: F02D 2200/0406 Intake manifold pressure
• CPC Class Codes: F02D 2200/0411 Volumetric efficiency
• CPC Class Codes: F02D 2200/0414 Air temperature
• CPC Class Codes: F02D 2200/703 Atmospheric pressure
• CPC Class Codes: F02D 41/0002 Controlling intake air
• CPC Class Codes: F02D 41/005 according to engine operating conditions
• CPC Class Codes: F02D 41/0052 Feedback control of engine parameters, e.g. for control of air/fuel ratio or intake air amount
• CPC Class Codes: F02D 41/0295 Control according to the amount of oxygen that is stored on the exhaust gas treating apparatus
• CPC Class Codes: F02D 41/144 Sensor in intake manifold
• CPC Class Codes: F02D 41/1458 with determination means using an estimation
• CPC Class Codes: F02D 41/146 the characteristics being an NOx content or concentration
• CPC Class Codes: F02D 41/1461 of the exhaust gases emitted by the engine
• CPC Class Codes: F02D 41/2422 Selective use of one or more tables
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

Various methods and systems are provided for controlling emissions. In one example, a controller is configured to respond to a sensed or estimated intake oxygen fraction by controlling an exhaust gas recirculation (EGR) amount supplied to an engine to maintain a level of particulate matter (PM) in a determined PM range and a level of NOx in a determined NOx range, and adjusting a target intake manifold oxygen fraction or target intake manifold EGR fraction in response to a NOx sensor feedback signal.

Claims

1. A system for an engine, comprising:

a controller configured to respond to a sensed or estimated intake oxygen fraction by controlling an exhaust gas recirculation (EGR) amount supplied to the engine to maintain a level of particulate matter (PM) in a determined PM range and a level of NOx in a determined NOx range, wherein the controller is further configured to adjust a target intake manifold oxygen fraction or target intake manifold EGR fraction in response to a NOx sensor feedback signal.

2. The system of claim 1, wherein the controller is configured to, after adjusting the target intake manifold oxygen fraction in response to the NOx sensor feedback signal, convert the target intake manifold oxygen fraction to a target fresh air fraction and change the EGR amount based on a difference between the target fresh air fraction and a fresh air fraction feedback value.

3. The system of claim 2, wherein the controller is configured to determine the fresh air fraction feedback value based on a measured EGR valve position, an intake manifold volumetric efficiency model, and an air-fuel ratio-based fresh air fraction estimation.

4. The system of claim 1, wherein the controller is configured to, after adjusting the target intake manifold EGR fraction in response to the NOx sensor feedback signal, control the EGR amount based on a difference between the target EGR fraction and an EGR fraction feedback value.

5. The system of claim 4, wherein the controller is configured to determine the EGR fraction feedback value based on a measured EGR valve position, an intake manifold volumetric efficiency model, and an air-fuel ratio-based EGR fraction estimation.

6. The system of claim 1, wherein the controller is further configured to adjust fuel injection timing to maintain the level of PM within the determined PM range, the fuel injection timing determined based on a reference injection timing output from a map and adjusted based on intake manifold temperature, the map selected from among a plurality of maps based on ambient temperature and pressure.

7. A system, comprising:

an engine having an intake manifold and a plurality of cylinders;

an exhaust gas recirculation (EGR) passage configured to flow EGR from at least a subset of the plurality of cylinders to the intake manifold; and

a controller configured to adjust a position of an EGR valve based on a target intake fresh air fraction, the target intake fresh air fraction determined based on a reference intake oxygen concentration and a corrected exhaust NOx concentration.

8. The system of claim 7, wherein the reference intake oxygen fraction is determined based on a map selected from among a plurality of maps based on one or more throttle positions, ambient temperature, and ambient pressure.

9. The system of claim 7, wherein the corrected exhaust NOx concentration is sensed from an exhaust NOx sensor and corrected based on exhaust oxygen concentration, engine speed, engine load, and fuel injection quantity.

10. The system of claim 9, wherein the corrected exhaust NOx concentration is further corrected based on humidity.

11. The system of claim 7, wherein the controller is further configured to adjust the target intake fresh air fraction based on a current EGR valve position and a corrected intake fresh air fraction.

12. The system of claim 11, wherein the corrected intake fresh air fraction is determined based on one or more of the current EGR valve position, an intake manifold volumetric efficiency model, and an air-fuel ratio based intake fresh air fraction estimation.

13. The system of claim 7, wherein in order to determine the target intake fresh air fraction based on the reference intake oxygen fraction and the corrected exhaust NOx concentration, the controller is configured to adjust the reference intake oxygen fraction based on the corrected exhaust NOx concentration and convert the adjusted reference intake oxygen fraction to the target intake fresh air fraction based on an oxygen-fuel ratio setpoint and cylinder air flow.

14. The system of claim 7, wherein the plurality of cylinders includes a donor cylinder group and a non-donor cylinder group, the donor cylinder group coupled to the EGR passage and the non-donor cylinder group coupled to an exhaust passage, wherein the EGR valve is positioned in the EGR passage.

15. The system of claim 14, wherein the EGR valve is a first EGR valve, and further comprising a second EGR valve positioned in a passage coupled between the EGR passage and the exhaust passage, and wherein the controller is configured to adjust a position of the second EGR valve based on the target intake fresh air fraction.

16. A method for an engine system, comprising:

transforming an intake oxygen concentration reference into a fresh air flow fraction reference or exhaust gas recirculation (EGR) fraction reference;

determining a first valve position command for a first EGR valve and a second valve position command for a second EGR valve based on the fresh air flow fraction reference or the EGR fraction reference;

setting a fresh air fraction command or EGR fraction command based on the first valve position command, the second valve position command, and output from one or more sensors of the engine system; and

adjusting a position of the first EGR valve and a position of the second EGR valve based on the fresh air fraction command or the EGR fraction command.

17. The method of claim 16, wherein the intake oxygen concentration reference is determined based on throttle position and exhaust NOx concentration.

18. The method of claim 17, wherein setting the fresh air fraction command or EGR fraction command based on the first valve position command, the second valve position command, and output from one or more sensors of the engine system comprises:

adjusting a position of the first EGR valve based on the first valve position command, and adjusting a position of the second EGR valve based on the second valve position command;

measuring an actual position of the first EGR valve and an actual position of the second EGR valve;

determining a fresh air fraction feedback value or an EGR fraction feedback value based on the actual position of the first EGR valve, the actual position of the second EGR valve, an intake manifold volumetric efficiency model, and an air-fuel ratio based intake fresh air fraction estimation; and

setting the fresh air fraction command or EGR fraction command based on the fresh air fraction feedback value or the EGR fraction feedback valve and the fresh air fraction reference or the EGR fraction reference.

19. The method of claim 16, wherein setting the fresh air fraction command or EGR fraction command based on the first valve position command, the second valve position command, and output from one or more sensors of the engine system comprises:

adjusting a position of the first EGR valve based on the first valve position command, and adjusting a position of the second EGR valve based on the second valve position command;

measuring an actual position of the first EGR valve and an actual position of the second EGR valve;

determining a fresh air fraction feedback value or an EGR fraction feedback value based on the actual position of the first EGR valve, the actual position of the second EGR valve, an intake manifold volumetric efficiency model, and an air-fuel ratio based intake fresh air fraction estimation; and

setting the fresh air fraction command or EGR fraction command based on the fresh air fraction feedback value or the EGR fraction feedback valve and the fresh air fraction reference or the EGR fraction reference.

20. The method of claim 19, wherein the adjusting of the position of the first EGR valve position is limited by the actual position of the second EGR valve.