EXHAUST GAS RECIRCULATION DIAGNOSTIC FOR COORDINATED TORQUE CONTROL SYSTEMS

• US 20100263627A1
• Filed: 01/05/2010
• Published: 10/21/2010
• Est. Priority Date: 04/17/2009
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (Motors Liquidation Co. GUC Trust)
• Inventors: Bonasse, Katie C., Kaiser, Jeffrey M., Whitney, Christopher E., York, Gregory J.
• Granted Patent: US 8,316,828 B2
• Time in Patent Office: Days
• US Class Current: 123/399
• CPC Class Codes: F02D 11/10 of the electric type
• CPC Class Codes: F02D 13/0219 by shifting the phase, i.e. the opening periods of the valves are constant
• CPC Class Codes: F02D 2200/1004 Estimation of the output torque
• CPC Class Codes: F02D 41/0002 Controlling intake air
• 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 41/1497 With detection of the mechanical response of the engine
• CPC Class Codes: F02M 26/05 High pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust system upstream of the turbine and reintroduced into the intake system downstream of the compressor
• CPC Class Codes: F02M 26/16 with EGR valves located at or near the connection to the exhaust system
• CPC Class Codes: F02M 26/49 Detecting, diagnosing or indicating an abnormal function of the EGR system

Abstract

A control system includes a throttle control module, an exhaust gas recirculation (EGR) control module, and a diagnostic control module. The throttle control module selectively maintains a desired throttle area when a vehicle is in a coastdown mode. The EGR control module opens an EGR valve when the desired throttle area is maintained. The diagnostic control module selectively diagnoses an error of an EGR system based on a pressure increase measured in an intake manifold of the vehicle when the EGR valve is open.

Claims

1. A control system, comprising:

a throttle control module that selectively maintains a desired throttle area when a vehicle is in a coastdown mode;

an exhaust gas recirculation (EGR) control module that opens an EGR valve when the desired throttle area is maintained; and

a diagnostic control module that selectively diagnoses an error of an EGR system based on a pressure increase measured in an intake manifold of the vehicle when the EGR valve is open.

2. The control system of claim 1, wherein the diagnostic control module diagnoses the error of the EGR system when the measured pressure increase is less than a minimum pressure increase.

3. The control system of claim 2, wherein the throttle control module refrains from maintaining the desired throttle area when the desired throttle area is greater than a maximum throttle area.

4. The control system of claim 2, wherein an air torque request is used to control air flow to one or more cylinders in the engine, and wherein the throttle control module allows adjustment of the desired throttle area when the air torque request is greater than a maximum torque request.

5. The control system of claim 2, wherein the throttle control module allows adjustment of the desired throttle area when an accelerator pedal position indicates that acceleration is requested.

6. The control system of claim 2, further comprising an air control module that determines the desired throttle area based on a minimum throttle area that provides a minimum air per cylinder (APC) to a cylinder of the engine.

7. The control system of claim 6, further comprising a minimum torque capacity module that determines the minimum APC based on at least one of a minimum controllable throttle position, a minimum consistent fuel injector on time, a minimum air density for self-sustaining combustion, and a minimum air flow for EGR diagnostic testing.

8. The control system of claim 7, further comprising an APC control module that determines a diagnostic APC based on the amount of opening of the EGR valve.

9. The control system of claim 8, wherein the minimum torque capacity module increases the minimum APC based on the diagnostic APC.

10. The control system of claim 9, wherein, before the throttle control module maintains the desired throttle area, the air control module determines the desired throttle area based on the increased minimum APC.

11. A method, comprising:

selectively maintaining a desired throttle area when a vehicle is in a coastdown mode;

opening an EGR valve when the desired throttle area is maintained; and

selectively diagnosing an error of an EGR system based on a pressure increase measured in an intake manifold of the vehicle when the EGR valve is open.

12. The method of claim 11, further comprising diagnosing the error of the EGR system when the measured pressure increase is less than a minimum pressure increase.

13. The method of claim 12, further comprising refraining from maintaining the desired throttle area when the desired throttle area is greater than a maximum throttle area.

14. The method of claim 12, further comprising:

using an air torque request to control air flow to one or more cylinders in the engine; and

allowing adjustment of the desired throttle area when the air torque request is greater than a maximum torque request.

15. The method of claim 12, further comprising allowing adjustment of the desired throttle area when an accelerator pedal position indicates that acceleration is requested.

16. The method of claim 12, further comprising determining the desired throttle area based on a minimum throttle area that provides a minimum air per cylinder (APC) to a cylinder of the engine.

17. The method of claim 16, further comprising determining the minimum APC based on at least one of a minimum controllable throttle position, a minimum consistent fuel injector on time, a minimum air density for self-sustaining combustion, and a minimum air flow for EGR diagnostic testing.

18. The method of claim 16, further comprising determining a diagnostic APC based on the amount of opening of the EGR valve.

19. The method of claim 18, further comprising increasing the minimum APC based on the diagnostic APC.

20. The method of claim 19, further comprising determining the desired throttle area based on the increased minimum APC before maintaining the desired throttle area.