EGR FLOW COMPENSATION FOR A DIESEL AIR HANDLING SYSTEM

• US 20110077838A1
• Filed: 09/25/2009
• Published: 03/31/2011
• Est. Priority Date: 09/25/2009
• Status: Active Grant

• Current Assignee: Cummins Incorporated
• Original Assignee: Cummins Incorporated
• Inventors: Gustafson, Richard J., Piper, Erik L., Osburn, Andrew W., Geveci, Mert
• Granted Patent: US 8,103,427 B2
• Time in Patent Office: Days
• US Class Current: 701/103
• CPC Class Codes: F02D 41/0007 for control of turbo-charged or super-charged engines control of the pumps per se F02B37/12
• 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 41/0072 Estimating, calculating or determining the EGR rate, amount or flow sensors in EGR systems F02M26/45
• CPC Class Codes: F02D 41/1454 the characteristics being an oxygen content or concentration or the air-fuel ratio
• CPC Class Codes: F02D 41/18 by measuring intake air flow
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

A method is disclosed for adjusting a target EGR mass flow in response to a current charge flow and target EGR fraction. The method includes interpreting an air-fuel ratio and a target air-fuel ratio. The method further includes interpreting a charge flow and a target EGR fraction. The method further includes determining an adjusted target EGR mass flow based on the air-fuel ratio, the target air-fuel ratio, the charge flow, and the target EGR fraction. The method further includes controlling an actuator based on the adjusted target EGR mass flow.

Claims

1. An apparatus, comprising:

an internal combustion engine including an intake manifold and an exhaust gas recirculation (EGR) device in fluid communication with the intake manifold;

a processing subsystem structured to;

interpret a charge flow and an air-fuel ratio;

interpret a target exhaust gas recirculation (EGR) fraction and a target air-fuel ratio;

determine an adjusted target EGR mass flow based on the air-fuel ratio, the target air-fuel ratio, the charge flow, and the target EGR fraction; and

provide the adjusted target EGR mass flow to an air handling controller.

2. The apparatus of claim 1, wherein the air handling controller is structured to control an EGR valve and a variable geometry turbocharger (VGT) in response to the adjusted target EGR mass flow.

3. The apparatus of claim 1, wherein the air handling controller is structured to replace a nominal target EGR mass flow with the adjusted target EGR mass flow.

4. The apparatus of claim 1, wherein the processing subsystem is further structured to determine the adjusted target EGR mass flow according to the equation:

5. The apparatus of claim 1, wherein the processing subsystem is further structured to interpret an oxygen fraction target and to estimate an oxygen fraction according to the equation:

6. The apparatus of claim 5, wherein the processing subsystem is further structured to determine the adjusted target EGR mass flow target according to the equation:

7. The apparatus of claim 3, wherein the air handling controller is structured to replace a nominal target EGR mass flow with the adjusted target EGR mass flow in response to one of an EGR valve actuator and a VGT actuator being saturated.

8. The apparatus of claim 3, wherein the air handling controller is structured to replace a nominal target EGR mass flow with the adjusted target EGR mass flow in response to the internal combustion engine experiencing a transient operation.

9. A method, comprising:

interpreting an air-fuel ratio and a target air-fuel ratio;

interpreting a charge flow and a target EGR fraction;

determining an adjusted target EGR mass flow based on the air-fuel ratio, the target air-fuel ratio, the charge flow, and the target EGR fraction; and

controlling at least one actuator based on the adjusted target EGR mass flow.

10. The method of claim 9, wherein the at least one actuator comprises an EGR valve actuator and a variable geometry turbocharger (VGT) actuator, wherein the adjusted target EGR mass flow is determined in response to the VGT actuator being saturated.

11. The method of claim 9, wherein the adjusted target EGR mass flow is determined according to the equation:

12. The method of claim 9, further comprising providing the adjusted target EGR mass flow to an air handling controller.

13. The method of claim 12, further comprising replacing a nominal target EGR mass flow with the adjusted target EGR mass flow.

14. The method of claim 9, further comprising interpreting a target oxygen fraction, and estimating an oxygen fraction according to the equation:

15. The method of claim 14, wherein the adjusted target EGR mass flow is determined according to the equation:

16. A system, comprising:

an internal combustion engine having a charge flow, an exhaust flow, an exhaust gas recirculation (EGR) flow path adapted to mix a portion of the exhaust flow into the charge flow;

an EGR valve disposed in the EGR flow path;

a variable geometry turbocharger (VGT) disposed in the exhaust flow;

a processing subsystem comprising;

an air handling controller comprising a nominal control module configured to provide a target air-fuel ratio (AFR) and a target EGR fraction, and an actuation module configured to operate the EGR valve and the VGT in response to the target AFR and target EGR fraction; and

an EGR adjustment controller comprising an input module configured to interpret a charge flow and an air-fuel ratio, an EGR correction module configured to determine an adjusted target EGR mass flow based on the air-fuel ratio, the target AFR, the charge flow, and the target EGR fraction, and an output module configured to provide the adjusted target EGR mass flow to the air handling controller.

17. The system of claim 16, wherein the air handling controller is structured to replace a nominal target EGR mass flow with the adjusted target EGR mass flow.

18. The system of claim 17, wherein the VGT includes a VGT actuator, wherein the air handling controller is further structured to replace the nominal target EGR mass flow with the adjusted target EGR mass flow in response to the VGT actuator being saturated.

19. The system of claim 16, wherein the EGR correction module is further configured to determine the adjusted target EGR mass flow according to the equation:

20. The system of claim 16, wherein the nominal control module is further configured to interpret an oxygen fraction target, and wherein the input module is further configured to estimate an oxygen fraction according to the equation:

21. The system of claim 20, wherein the EGR correction module is further configured to determine the adjusted target EGR mass flow according to the equation:

22. A method, comprising:

operating an internal combustion engine including an intake manifold and an EGR device in fluid communication with the intake manifold;

providing a charge to the internal combustion engine from the intake manifold, the charge including intake air and recirculated exhaust gas from the EGR device;

establishing a current ratio between fuel and air, a target ratio between fuel and air, a recirculated exhaust gas fraction of the charge, and a charge flow rate; and

determining a change in a target flow rate of the recirculated exhaust gas as a function of the current ratio, the target ratio, the recirculated exhaust gas fraction, and the charge flow rate; and

in response to the change in the target flow rate, adjusting flow of the recirculated exhaust gas with the EGR device to regulate oxygen fraction of the charge.

23. The method of claim 22, wherein the change in a target flow rate of the recirculated exhaust gas is determined according to the equation: