EGR detection via humidity detection

• US 7,715,976 B1
• Filed: 04/02/2009
• Issued: 05/11/2010
• Est. Priority Date: 04/02/2009
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Xiao, Nian, Kerns, James Michael, Ding, Yi
• Primary Examiner(s): SOLIS, ERICK R
• Application Number:
  US12/417,373
• Time in Patent Office: 404 Days
• Field of Search: 701/108, 123/406.44, 123/406.45, 123/406.48, 123/568.11, 123/568.16, 123/568.22, 731/147.1, 731/147.4
• US Class Current: 701/108
• CPC Class Codes: F02B 47/10 Circulation of exhaust gas in closed or semi-closed circuits, e.g. with simultaneous addition of oxygen
• CPC Class Codes: F02D 13/0207 changing valve lift or valve lift and timing
• CPC Class Codes: F02D 13/0219 by shifting the phase, i.e. the opening periods of the valves are constant
• CPC Class Codes: F02D 2200/0418 Air humidity
• 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: F02M 26/46 for determining the characteristics of gases, e.g. composition
• CPC Class Codes: F02M 26/47 the characteristics being temperatures, pressures or flow rates
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

Various systems and methods are described for controlling an engine in a vehicle which includes an exhaust passage and an exhaust gas recirculation system. One example method comprises adjusting an engine operating parameter based on an exhaust gas recirculation amount, the exhaust gas recirculation amount based on a first humidity and a second humidity, the first humidity generated from a first humidity sensor at a first location and the second humidity generated from a second humidity sensor located in the exhaust passage of the engine.

Claims

1. A method for controlling an engine in a vehicle during engine operation, the engine having an exhaust passage and an exhaust gas recirculation system, the method comprising:

adjusting an engine operating parameter based on an exhaust gas recirculation amount, the exhaust gas recirculation amount based on a first humidity and a second humidity, the first humidity generated from a first humidity sensor at a first location in an intake manifold of the engine, the second humidity generated from a second humidity sensor at a second location in an exhaust manifold of the engine.

2. The method of claim 1 wherein the vehicle further comprises a third humidity sensor located outside of the engine for generating an ambient humidity, the method further comprising determining the exhaust gas recirculation amount based on the third humidity sensor.

3. The method of claim 2 wherein determining the exhaust gas recirculation amount is based on a balance of an ambient water mass and an exhaust water mass in the intake manifold.

4. The method of claim 1 wherein the engine operating parameter includes spark timing.

5. The method of claim 1 wherein, in at least one condition, spark timing is advanced in response to the exhaust gas recirculation amount increasing.

6. The method of claim 1 wherein an air-fuel ratio of the engine is variable.

7. The method of claim 1 wherein the engine is a flex fuel engine.

8. A method of controlling an engine in a vehicle during engine operation, the engine having an exhaust gas recirculation system and an exhaust system, the method comprising:

during engine non-fueling conditions, generating an intake humidity via a first sensor and an exhaust humidity via a second sensor, the second sensor positioned in an exhaust gas flow of the engine, the exhaust gas flow directed to a tailpipe of the exhaust system;

during engine fueling conditions in which exhaust gas recirculation is off, generating an intake humidity via the first sensor; and

identifying degradation based on the generated humidities.

9. The method of claim 8 wherein engine non-fueling conditions include deceleration fuel shut off.

10. The method of claim 8 wherein the vehicle further comprises a third humidity sensor located outside of the engine for generating an ambient humidity, the method further comprising identifying degradation based on the third humidity sensor.

11. The method of claim 8 wherein degradation is identified when the intake humidity and ambient humidity differ greater than a threshold amount.

12. The method of claim 11 wherein degradation includes exhaust gas recirculation valve degradation.

13. The method of claim 9 wherein degradation is identified when the intake humidity, the exhaust humidity, and the ambient humidity generated during non-fueling conditions in which exhaust gas recirculation is off differ greater than a threshold amount.

14. The method of claim 13 wherein degradation includes humidity sensor degradation.

15. The method of claim 8 wherein identifying degradation includes differentiating between EGR valve degradation and humidity sensor degradation based on the generated humidities.

16. A system for an engine in a vehicle, the system comprising:

an exhaust gas recirculation system;

at least two humidity sensors coupled to the engine, a first sensor being located in an intake manifold and a second sensor being located in an exhaust manifold upstream of the exhaust gas recirculation system; and

a control system including a computer readable storage medium, the medium including instructions thereon, the control system receiving communication from the humidity sensors, the medium comprising;

instructions for identifying an amount of exhaust gas recirculation, where the identified exhaust gas recirculation amount is based on humidity readings generated by the at least two humidity sensors, as well as an ambient humidity, and instructions for adjusting an engine operating condition in response to the identified exhaust gas recirculation amount.

17. The system of claim 16 wherein a third sensor is located outside of the engine for generating the ambient humidity.

18. The system of claim 16 further comprising instructions for identifying humidity sensor degradation based on humidity readings generated during engine non-fueling conditions in which an exhaust gas recirculation valve is closed.

19. The system of claim 16 further comprising instructions for identifying exhaust gas recirculation valve degradation based on humidity readings generated during conditions in which an exhaust gas recirculation valve is closed.

20. The system of claim 18 wherein identifying humidity sensor degradation includes differentiating which among the at least two humidity sensors is degraded based on a difference greater than a threshold amount between the humidity reading of one sensor and the humidity readings of the other sensors.