Fuel vapor purging diagnostics

• US 8,312,765 B2
• Filed: 03/06/2009
• Issued: 11/20/2012
• 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: Pursifull, Ross Dykstra, Lippa, Allan J., Russell, John D., Surnilla, Gopichandra, Ulrey, Joseph Norman
• Primary Examiner(s): MCCALL, ERIC SCOTT
• Application Number:
  US12/399,213
• Publication Number:
  US 20100223984A1
• Time in Patent Office: 1,355 Days
• Field of Search: 731/143.8, 731/143.9, 731/144.2, 731/144.3
• US Class Current: 73/114.39
• CPC Class Codes: F02M 25/0809 Judging failure of purge control system
• 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: G01M 15/04 Testing internal-combustion engines

Abstract

Systems and methods are provided for monitoring reverse flow of fuel vapors and/or air through a vehicle fuel vapor recovery system, the fuel vapor recovery system coupled to an engine intake of a boosted internal combustion engine. One example method comprises, intermittently adjusting a restriction in the fuel vapor recovery system during boosted conditions, and indicating degradation based on one or more of a change in a pressure value, or based on a change in flow in the fuel vapor recovery system.

Claims

1. A method for a vehicle fuel vapor system coupled to an engine intake, comprising:

during boosted conditions, intermittently adjusting a restriction in the fuel vapor system, the restriction downstream of a valve; and

indicating degradation, including reverse flow of gases from the engine intake to the fuel vapor system, based on one or more of a change in a pressure or flow value in the fuel vapor system that correlates to the intermittent adjusting.

2. The method of claim 1 wherein the pressure value includes at least one of a fuel vapor system pressure, an engine intake manifold pressure, a rate of change of the pressure value, or a pressure difference between a first pressure value estimated before adjusting the restriction and a second pressure value estimated after adjusting the restriction.

3. The method of claim 2 wherein the fuel vapor system pressure is estimated by a fuel tank pressure transducer coupled between a fuel tank and the engine intake, and wherein the manifold pressure is estimated by a manifold pressure sensor coupled to the engine intake.

4. The method of claim 2 wherein indicating degradation based on a change in pressure value includes indicating degradation when the change in pressure value is greater than a threshold and setting a diagnostic code.

5. The method of claim 4 further comprising, disabling boost responsive to the indication of degradation, the disabling of boost including disabling operation of a boosting device coupled in the engine intake.

6. The method of claim 3 wherein the fuel tank pressure transducer is coupled to a venturi, and wherein indicating degradation based on a change in flow includes indicating degradation based on the presence of a flow across the venturi.

7. The method of claim 6 wherein indicating degradation based on the presence of the flow across the venturi includes indicating degradation based on a pressure difference across the venturi being greater than a threshold.

8. The method of claim 1 wherein intermittently adjusting a restriction includes intermittently sealing the fuel vapor system from the atmosphere by intermittently commanding a canister vent valve to be closed.

9. The method of claim 1 wherein intermittently adjusting a restriction includes intermittently sealing the fuel vapor system from the intake by intermittently commanding a canister purge valve to be closed.

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

a control system configured to,

intermittently adjust a restriction in the fuel vapor system during a boosted condition; and

indicate degradation, including reverse flow of gases from the engine intake to the fuel vapor system, based on at least one of a change in pressure or flow value in the fuel vapor system that correlates to the intermittent adjusting.

11. The system of claim 10 wherein intermittently adjusting a restriction includes intermittently sealing the fuel vapor system from the atmosphere by intermittently commanding the canister vent valve to be closed.

12. The system of claim 11 further comprising a tank isolation valve, wherein intermittently adjusting a restriction further includes intermittently commanding the tank isolation valve to be closed.

13. The system of claim 12 wherein a fuel tank pressure sensor is positioned between the tank isolation valve and the fuel tank.

14. The system of claim 11 wherein the pressure value includes at least one of a fuel vapor system pressure estimated by the fuel tank pressure transducer, a manifold pressure estimated by a manifold pressure sensor, a rate of change of the pressure value, and a pressure difference between a first pressure value estimated before adjusting the restriction and a second pressure value estimated after adjusting the restriction.

15. The system of claim 14 wherein indicating degradation based on the change in pressure value includes indicating degradation when the change in pressure value is greater than a threshold, a controller further configured to set a diagnostic code and disable boost responsive to the indication of degradation, the disabling of boost including disabling operation of a boosting device coupled in the engine intake.

16. The system of claim 11 wherein the fuel tank pressure transducer is coupled to a venturi, and wherein indicating degradation based on the change in flow value includes indicating degradation based on the presence of a flow across the venturi.

17. The system of claim 16 wherein indicating degradation further includes indication degradation of the check valve.

18. A method of monitoring reverse flow of fuel vapors and/or air through a vehicle fuel vapor system including a fuel tank pressure transducer, a fuel vapor canister, a canister purge valve, and a canister vent valve, a fuel tank pressure sensor positioned between the fuel vapor canister and a fuel tank, said fuel vapor system coupled to an engine intake of a boosted internal combustion engine, the method comprising:

intermittently adjusting a restriction in the fuel vapor recovery system during boost, and indicating degradation, including reverse flow of fuel vapors and/or air through the vehicle fuel vapor system, based on at least one of a change in a pressure or flow value in the fuel vapor system that correlates to the intermittent adjusting.

19. The method of claim 18 wherein intermittently adjusting a restriction includes commanding the fuel vapor system to be sealed from the engine intake by commanding the canister purge valve to be closed, and intermittently sealing the fuel vapor system from the atmosphere by intermittently commanding the canister vent valve to be closed.

20. The method of claim 19 wherein the fuel vapor system further includes a tank isolation valve, and wherein intermittently adjusting a restriction further includes intermittently commanding the tank isolation valve to be closed.

21. The method of claim 20 wherein the pressure value includes at least one of a fuel vapor recovery system pressure estimated by the fuel tank pressure transducer, a manifold pressure estimated by a manifold pressure sensor, a rate of change of the pressure value, and a pressure difference between a first pressure value estimated before adjusting the restriction and a second pressure value estimated after adjusting the restriction.