Automotive Fuel System Leak Testing

• US 20110139130A1
• Filed: 07/14/2010
• Published: 06/16/2011
• Est. Priority Date: 07/14/2010
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Siddiqui, Shahid Ahmed
• Granted Patent: US 8,074,627 B2
• Time in Patent Office: Days
• US Class Current: 123/520
• CPC Class Codes: F02D 41/042 for stopping the engine
• CPC Class Codes: F02D 41/3082 Control of electrical fuel pumps
• CPC Class Codes: F02M 25/0818 having means for pressurising the evaporative emission space

Abstract

Systems and methods for performing leak testing on fuel system components in hybrid vehicles during engine-off operating conditions are disclosed. For example, a fuel tank may include a pressure accumulator which may be filled with fuel via a fuel pump in order to generate a vacuum which may be used to diagnose leaks in the fuel system.

Claims

1. A method of operating an engine emission control system including a fuel vapor retaining device coupled to a fuel tank, comprising:

during an engine off condition, selectively operating a fuel pump to store at least some pressure in an accumulator coupled to the fuel pump; and

indicating a leak in the emission control system in response to the stored pressure.

2. The method of claim 1, wherein the fuel vapor retaining device is coupled to the fuel tank through a valve.

3. The method of claim 1, wherein selectively operating the fuel pump includes operating the pump until a pressure in the accumulator reaches a threshold, and then discontinuing operation of the fuel pump.

4. The method of claim 1, wherein selectively operating the pump includes operating the pump for a selected duration, the duration selected based on accumulator pressure.

5. The method of claim 1, wherein the accumulator is positioned within the fuel tank.

6. The method of claim 1, wherein a leak is indicated in the fuel tank in response to the stored pressure.

7. The method of claim 1, wherein a leak is indicated in the fuel vapor retaining device in response to the stored pressure.

8. A method of operating an engine emission control system in a hybrid vehicle including a fuel tank, comprising:

during an engine-off condition, isolating the fuel tank from the atmosphere, and selectively operating a fuel pump to store at least some fuel in an accumulator coupled to the fuel pump and positioned within the fuel tank; and

indicating a fuel tank leak in response to a pressure change after fuel is stored in the accumulator.

9. The method of claim 8, wherein the engine emission control system includes a fuel vapor retaining device coupled to the fuel tank through a valve.

10. The method of claim 8, wherein selectively operating the fuel pump includes operating the pump until a pressure in the accumulator reaches a threshold, and then discontinuing operation of the fuel pump.

11. The method of claim 8, wherein selectively operating the pump includes operating the pump for a selected duration, the duration selected based on accumulator pressure.

12. The method of claim 8, further comprising, following an operation of the fuel pump to store at least some fuel in an accumulator coupled to the fuel pump, opening a communication between the fuel tank and a secondary device and indicating a leak in the secondary device in response to a pressure change in said secondary device.

13. The method of claim 12, wherein the secondary device is a fuel vapor canister, and the method further comprises isolating the fuel vapor canister from the atmosphere before opening a communication between the fuel tank and the fuel vapor canister.

14. The method of claim 8, further comprising during engine-off conditions opening a communication between the fuel tank and a secondary device in response to a duration of an operation of the fuel pump greater than a threshold duration and indicating a leak in the secondary device in response to a pressure change in the secondary device.

15. The method of claim 8, wherein the accumulator includes a bladder within a rigid bottle and a drain line with an aperture, the drain line with an aperture including a sealing member configured to seal the aperture when the fuel pump is in operation and allow fuel in the accumulator to drain into the tank when the fuel pump is not in operation.

16. The method of claim 8, wherein said indicating includes reporting said leak to an onboard diagnostic system in the vehicle, the method further comprising, during engine running conditions, operating the fuel pump to deliver fuel from the fuel tank to a fuel rail of the engine to supply fuel to the engine for combustion in the engine.

17. The method of claim 8, wherein the pressure change is based on an initial pressure before the fuel pump is operated and a final pressure when the fuel pump is stopped.

18. A hybrid vehicle system, comprising:

an engine emission control system including a fuel vapor retaining device coupled to a fuel tank through a valve;

a fuel pump within the fuel tank coupled to a pressure accumulator device within the fuel tank;

a pressure sensor disposed within the fuel tank; and

a computer readable storage medium having instructions encoded thereon, including;

instructions to, during an engine off condition, selectively operate a fuel pump to store at least some pressure in the accumulator;

instructions to indicate a leak in the emission control system in response to the stored pressure; and

instructions to, during an engine running condition, operate the fuel pump to deliver fuel to the engine and initiate a spark in the cylinder to combust the delivered fuel.

19. The system of claim 18, wherein the pressure accumulator device includes a bladder within a rigid bottle and a drain line with an aperture, the drain line with an aperture including a sealing member configured to seal the aperture when the fuel pump is in operation and allow fuel in the accumulator to drain into the tank when the fuel pump is not in operation.

20. The system of claim 19, wherein the sealing member is configured to seal the aperture via a plurality of springs coupled to the sealing member and a perimeter of the aperture.