System for Determining EGR Cooler Degradation

• US 20120290190A1
• Filed: 05/13/2011
• Published: 11/15/2012
• Est. Priority Date: 05/13/2011
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Kim, Yong-Wha, Van Nieuwstadt, Michiel J., Kurtz, Eric
• Granted Patent: US 9,476,387 B2
• Time in Patent Office: Days
• US Class Current: 701/102
• CPC Class Codes: F02D 2041/0067 Determining the EGR temperature
• CPC Class Codes: F02M 26/25 with coolers having bypasses
• CPC Class Codes: F02M 26/27 with air-cooled heat exchangers
• CPC Class Codes: F02M 26/33 controlling the temperature of the recirculated gases
• CPC Class Codes: F02M 26/47 the characteristics being temperatures, pressures or flow rates
• CPC Class Codes: F02M 26/49 Detecting, diagnosing or indicating an abnormal function of the EGR system

Abstract

Systems and methods for diagnosing an EGR system are presented. The method provides for indicating EGR system degradation in response to a temperature at an outlet of an EGR cooler. The method may require less calibration effort than a model based diagnostic.

Claims

1. An EGR system diagnostic method, comprising:

operating an engine with an EGR bypass valve in a first state for a time greater than a threshold amount of time;

indicating a condition of EGR cooler system degradation in response to a request to transition the EGR bypass valve to a second state and a temperature difference between an actual EGR gas temperature and an expected EGR gas temperature before transitioning the state of the EGR bypass valve.

2. The method of claim 1, where the EGR bypass valve is open in the first state and closed in the second state, and where the EGR cooler system degradation is temperature control degradation.

3. The method of claim 1, where the EGR bypass valve is closed in the first state and open in the second state.

4. The method of claim 1, further comprising comparing an expected combustion phasing to a measured combustion phasing during the first state and suppressing indicating the condition of EGR cooler system degradation when a difference between the expected combustion phasing and the measured combustion phasing is less that a threshold.

5. The method of claim 1, further comprising comparing an expected rate of particulate matter production to a measured rate of particulate matter production during the first state and suppressing indicating the condition of EGR cooler system degradation when a difference between the expected rate of particulate matter production and the measured rate of particulate matter production is less that a threshold.

6. The method of claim 1, further comprising comparing an expected rate of NOx production to a measured rate of NOx production during the first state and suppressing indicating the condition of EGR cooler system degradation when a difference between the expected rate of NOx production and the measured rate of NOx production is less that a threshold.

7. An EGR system diagnostic method, comprising:

operating an engine with an EGR bypass valve in a first state;

commanding transitioning the EGR bypass valve to a second state; and

indicating a condition of EGR cooler system temperature control degradation in response to a difference in combustion phasing and a EGR temperature determined after commanding transitioning the EGR bypass valve to the second state.

8. The method of claim 7, where the difference in combustion phasing is greater or less than an expected combustion phasing by a threshold amount.

9. A method of claim 7, where the EGR temperature determined after commanding transitioning the EGR bypass valve to the second state varies from an EGR temperature determined when the EGR bypass valve is in the first state by less than a predetermined amount.

10. The method of claim 7, where indicating the condition of EGR cooler system degradation is further based on particulate matter production of the engine.

11. The method of claim 10, where particulate matter production of the engine varies by less than a predetermined amount in response to commanding transitioning the EGR bypass valve to the second state.

12. The method of claim 7, where indicating the condition of EGR cooler system degradation is further based on engine NOx production.

13. The method of claim 7, where indicating the condition of EGR cooler system degradation is further based on engine intake air oxygen concentration.

15. An EGR system, comprising:

an engine;

an EGR cooler in communication with the engine;

an EGR cooler bypass circuit;

a valve directing EGR gases to the EGR cooler in a first state, the valve directing EGR gases to bypass the EGR cooler in a second state; and

a controller, the controller including instructions to indicate a condition of EGR cooler system degradation in based on a request to transition the EGR bypass valve to a second state and a temperature difference between an actual EGR temperature and an expected EGR temperature at a time greater than the threshold amount of time and before transitioning the state of the EGR bypass valve, the controller including further instructions to indicate the condition of EGR cooler system degradation based on NOx produced by the engine.

14. The method of claim 15, where engine intake air oxygen concentration varies less than a predetermined amount in response to commanding transitioning the EGR bypass valve to the second state.

16. The EGR system of claim 15, where the controller includes further instructions for inhibiting indicating the condition of EGR cooler system degradation in response to combustion phasing.

17. The EGR system of claim 16, further comprising a knock sensor for determining combustion phasing.

18. The EGR system of claim 16, further comprising a pressure sensor for determining combustion phasing.

19. The EGR system of claim 16, where the controller includes further instructions for inhibiting indicating the condition of EGR cooler system degradation in response to particulate matter production via an engine, the EGR system coupled to the engine.

20. The EGR system of claim 15, where the controller includes further instructions for inhibiting indicating the condition of EGR cooler system degradation in response to exhaust gas oxygen concentration.