FUEL VAPOR PURGING DIAGNOSTICS

• US 20100224171A1
• Filed: 03/06/2009
• Published: 09/09/2010
• Est. Priority Date: 03/06/2009
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Bohr, Scott, Peters, Mark William, Shimon, Richard, Jentz, Robert Roy, Pursifull, Ross Dykstra
• Granted Patent: US 7,810,475 B2
• Time in Patent Office: Days
• US Class Current: 123/520
• CPC Class Codes: F02M 25/0836 Arrangement of valves controlling the admission of fuel vapour to an engine, e.g. valve being disposed between fuel tank or absorption canister and intake manifold
• CPC Class Codes: F02M 25/089 Layout of the fuel vapour installation

Abstract

Systems and methods are provided for monitoring reverse flow of fuel vapors and/or air through a vehicle fuel vapor recovery system, said fuel vapor recovery system coupled to an engine intake of a boosted internal combustion engine. One example method comprises, during boost, when the fuel vapor recovery system is commanded to be sealed from the intake, indicating degradation based on a pressure value in the fuel vapor recovery system.

Claims

1. A method of monitoring reverse flow of fuel vapors and/or air through a vehicle fuel vapor recovery system, said fuel vapor recovery system coupled to an engine intake of a boosted internal combustion engine, the method comprising:

during boost, when the fuel vapor recovery system is commanded to be sealed from the intake, indicating degradation based on a pressure value in the fuel vapor recovery system.

2. The method of claim 1 wherein the fuel vapor recovery system includes a canister purge valve coupled between a fuel vapor canister and the engine intake, the canister purge valve adjusting flow from the fuel vapor recovery system to the engine intake, and wherein commanding the fuel vapor recovery system to be sealed from the intake includes commanding the canister purge valve to be closed.

3. The method of claim 2 wherein indicating degradation based on the pressure value includes indicating degradation when the pressure value is greater than a threshold, the threshold adjusted responsive to a boost pressure.

4. The method of claim 3 wherein the pressure value includes a fuel vapor recovery system pressure, the fuel vapor recovery system pressure estimated by a fuel tank pressure transducer coupled between the engine intake and a fuel tank.

5. The method of claim 4 wherein the pressure value includes a pressure difference between a first pressure value estimated before sealing the system from the intake and a second pressure value estimated after sealing the system from the intake.

6. The method of claim 4 wherein the pressure value includes a rate of pressure change.

7. The method of claim 4 wherein indicating degradation further comprises setting a diagnostic code, the method further comprising disabling boost responsive to the indication of degradation.

8. The method of claim 2 wherein the fuel vapor recovery system includes a tank isolation valve coupled between the fuel vapor canister and a fuel tank, the method further comprising commanding the tank isolation valve to be closed.

9. A system, comprising:

an engine comprising an intake;

a boosting device with a compressor configured to provide a boost to the engine intake;

a fuel vapor recovery system coupled to the engine intake, said fuel vapor recovery system including a pressure transducer, a fuel vapor canister, a canister purge valve, and a canister vent valve; and

a control system configured to,

command the fuel vapor recovery system to be at least partially un-sealed from the intake during at least a boosted condition; and

indicate degradation based on the pressure transducer.

10. The system of claim 9 wherein the pressure transducer is positioned between the fuel vapor canister and a fuel tank.

11. The system of claim 9 wherein commanding the fuel vapor recovery system to be at least partially un-sealed from the intake includes commanding the canister purge valve to be at least partially open.

12. The system of claim 11 wherein indicating degradation based on the pressure transducer includes indicating degradation when a pressure value is greater than a threshold, the threshold adjusted responsive to a boost pressure.

13. The system of claim 12 wherein the pressure value includes a fuel vapor recovery system pressure estimated by the pressure transducer.

14. The system of claim 12 wherein the controller is further configured to command the fuel vapor recovery system to be sealed from the atmosphere by commanding the canister vent valve to be closed, and wherein the pressure value includes a pressure difference between a first pressure value estimated before sealing the system from the atmosphere and a second pressure value estimated after sealing the system from the atmosphere.

15. The system of claim 12 wherein the pressure value includes a rate of pressure change.

16. The system of claim 12 wherein indicating degradation further comprises setting a diagnostic code, the method further comprising disabling boost responsive to the indication of degradation.

17. The system of claim 12 wherein the fuel vapor recovery system further includes a canister check valve coupled in series with the canister purge valve, and wherein indicating degradation includes indicating check valve degradation.

18. The system of claim 14 wherein the fuel vapor recovery system further includes a tank isolation valve, and wherein the controller is further configured to command the tank isolation valve to be closed.

19. A method of monitoring reverse flow of fuel vapors and/or air through a vehicle fuel vapor recovery system, said fuel vapor recovery system coupled to an engine intake of a boosted internal combustion engine, the fuel vapor recovery system including a fuel tank pressure transducer, the method comprising:

during boost, when the fuel vapor recovery system is commanded to be sealed from the intake, indicating degradation based on a presence of a flow through the fuel vapor recovery system.

20. The method of claim 19 wherein the fuel vapor recovery system includes a canister purge valve coupled between a fuel vapor canister and the engine intake, the canister purge valve adjusting flow between the fuel vapor recovery system and the engine intake, and wherein commanding the fuel vapor recovery system to be sealed from the intake includes commanding the canister purge valve to be closed.

21. The method of claim 20 wherein the fuel tank pressure transducer is coupled to a venturi.

22. The method of claim 21 wherein indicating degradation based on the flow includes indicating degradation based on a pressure value in the fuel vapor recovery system being lower than a threshold.

23. The method of claim 21 wherein the pressure value includes a fuel vapor recovery system pressure estimated by the fuel tank pressure transducer coupled to the venturi.

24. A method of monitoring reverse flow of fuel vapors and/or air through a vehicle fuel vapor recovery system, said fuel vapor recovery system coupled to an engine intake of a boosted internal combustion engine, the fuel vapor recovery system including a fuel tank pressure transducer, the method comprising:

during boost, when the fuel vapor recovery system is commanded to be at least partially un-sealed from the intake, indicating degradation based on a flow as indicated by the fuel tank pressure transducer.

25. The method of claim 24 wherein the fuel vapor recovery system includes a canister purge valve coupled between a fuel vapor canister and the engine intake, the canister purge valve adjusting flow between the fuel vapor recovery system and the engine intake, and wherein commanding the fuel vapor recovery system to be at least partially un-sealed from the intake includes commanding the canister purge valve to be opened.

26. The method of claim 25 wherein the fuel tank pressure transducer is coupled to a venturi.

27. The method of claim 26 wherein indicating degradation based on the flow as indicated by the fuel tank pressure transducer includes indicating degradation based on a pressure value in the fuel vapor recovery system being lower than a threshold.