Fuel delivery system diagnostics after shut-down

• US 8,191,533 B2
• Filed: 07/09/2010
• Issued: 06/05/2012
• Est. Priority Date: 04/22/2008
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Ulrey, Joseph Norman, Pursifull, Ross Dykstra, Brehob, Diana D.
• Primary Examiner(s): Cronin, Stephen K
• Assistant Examiner(s): VILAKAZI, SIZO BINDA
• Application Number:
  US12/833,714
• Publication Number:
  US 20100275880A1
• Time in Patent Office: 697 Days
• Field of Search: 123/359, 123/447, 123/456, 123/457, 123/458, 123/463, 123518-521, 123/198.D, 123/198.DB, 123/446, 73/40, 73/491, 73/492, 73/493, 73/497, 731/143.8, 731/144.1, 731/144.2, 731/144.3
• US Class Current: 123/456
• CPC Class Codes: F02B 1/12 with compression ignition with fuel-air charge ignited by compression ignition of an additional fuel F02B7/00
• CPC Class Codes: F02D 2041/224 Diagnosis of the fuel system
• CPC Class Codes: F02D 2041/225 Leakage detection
• CPC Class Codes: F02D 41/042 for stopping the engine
• CPC Class Codes: F02D 41/22 Safety or indicating devices for abnormal conditions in air/fuel ratio feedback systems F02D41/1495, in electric control linkage F02D11/107, in purge control systems F02M25/0809
• CPC Class Codes: F02D 41/3845 by controlling the flow into the common rail, e.g. the amount of fuel pumped
• CPC Class Codes: F02M 63/022 by acting on fuel control mechanism

Abstract

A method for operation of an engine fuel system includes initiating a mitigating action based on a fuel rail pressure response, the fuel rail pressure response occurring after an engine shut-down. The mitigating action includes disabling vehicle operation if fuel rail pressure drops below a threshold value after activation of one of the higher or lower pressure pumps, the activation occurring before a subsequent engine start. In this way, a distinction can be made between internal and external leaks, allowing the mitigating action taken to be adjusted accordingly.

Claims

1. A method for operation of a fuel delivery system in an internal combustion engine including a lower pressure pump, a higher pressure pump fluidly coupled downstream of the lower pressure pump, and a fuel rail fluidly coupled downstream of the high pressure pump comprising:

initiating a mitigating action based on a fuel rail pressure and temperature response profile, the fuel rail pressure response occurring after an engine shut-down, where the mitigating action includes disabling vehicle operation if fuel rail pressure drops below a threshold value after activation of one of the pumps, the activation occurring before a subsequent engine start, the subsequent engine start occurring after the engine shut-down, and where the mitigating action includes adjusting operation of one of the pumps during the subsequent engine start if fuel rail pressure achieves at least the threshold value after or during the activation.

2. The method of claim 1 wherein activation of one or more of the pumps includes activating and deactivating the lower pressure pump.

3. The method of claim 2 wherein the lower pressure pump is activated between 1 and 2 seconds.

4. The method of claim 1 wherein mitigating action is initiated based on a fuel rail pressure and temperature response profile.

5. The method of claim 4 wherein the pressure profile includes two or more measurements of the fuel in the fuel rail, and where the temperature profile includes two or more measurements of engine temperature.

6. The method of claim 5 wherein respective pairs of the temperature and pressure measurements are substantially concurrent.

7. The method of claim 1 wherein the lower pressure pump is a lift pump.

8. The method of claim 1 further comprising indicating an external leak when the fuel rail pressure drops below a threshold pressure and indicating an internal leak when the fuel rail pressure achieves at least the threshold value after or during the activation.

9. The method of claim 1 wherein the mitigating action includes adjusting an injection profile during the subsequent start based on the pressure response.

10. The method of claim 1 wherein the mitigating action includes setting a diagnostic code.

11. The method of claim 1 wherein the mitigating action includes delaying activation of a pump during the subsequent start.

12. The method of claim 1 wherein the mitigating action includes disabling both pumps during the subsequent start.

13. A method for operation of a fuel delivery system in an internal combustion engine having a fuel system including a lower pressure pump, a higher pressure pump fluidly coupled downstream of the lower pressure pump, and a fuel rail fluidly coupled downstream of the high pressure pump comprising:

indicating a fuel system leak based on a fuel rail pressure response and a temperature response, the fuel rail pressure and temperature response occurring after an engine shut-down; and

in response to the indication and before a subsequent engine start, the subsequent engine start occurring after the engine shut-down, activating and then deactivating the lower pressure pump;

disabling vehicle operation if fuel rail pressure drops below a threshold value during or after the activation of the lower pressure pump; and

adjusting operation of one of the pumps during the subsequent engine start if fuel rail pressure achieves at least the threshold value during or after the activation of the lower pressure pump.

14. The method of claim 13 where the fuel rail pressure and temperature response includes two or more substantially concurrent temperature and pressure measurements while the fuel system is in a closed volume state.

15. The method of claim 14 wherein the pressure measurements include a difference between a measured pressure, taken after the activation and deactivation of the lower pressure pump, and a previous pressure measurement.

16. The method of claim 15 wherein the previous pressure measurement includes a regulated pressure during a key-off condition.

17. The method of claim 13 further comprising indicating an external leak if fuel rail pressure drops below a threshold value during or after the activation of the lower pressure pump.

18. The method of claim 17 further comprising indicating an internal leak if fuel rail pressure achieves at least the threshold value during or after the activation of the lower pressure pump.

19. An article of manufacture for controlling operation of a fuel delivery system in an internal combustion engine having a fuel system including a lower pressure pump, a higher pressure pump fluidly coupled downstream of the lower pressure pump, and a fuel rail fluidly coupled downstream of the high pressure pump, the article comprising:

code for indicating a fuel system leak based on a plurality of concurrent fuel rail pressure and temperature measurements, at least some of the fuel rail pressure and temperature measurements taken after an engine shut-down; and

code for, in response to the indication and before a subsequent engine start, the subsequent engine start occurring after the engine shut-down, activating and then deactivating the lower pressure pump;

code for disabling vehicle operation and indicating an external leak if fuel rail pressure drops below a threshold value during or after the activation of the lower pressure pump; and

code for adjusting operation of one of the pumps during the subsequent engine start and indicating an internal leak if fuel rail pressure achieves at least the threshold value during or after the activation of the lower pressure pump.

20. The article of claim 19 further comprising code for setting a diagnostic code readable by a universal code reader, the setting responsive to each of the indication of a fuel leak, the indication of an internal leak, and the indication of the external leak.