LEAK DETECTION BASED ON FUEL LEVEL

• US 20150025722A1
• Filed: 07/18/2013
• Published: 01/22/2015
• Est. Priority Date: 07/18/2013
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Pearce, Russell Randall, Bohr, Scott A., Dudar, Aed M., Yang, Dennis Seung-Man
• Granted Patent: US 9,091,227 B2
• Time in Patent Office: Days
• US Class Current: 701/22
• CPC Class Codes: B60K 2015/03514 with vapor recovery means
• CPC Class Codes: B60W 20/50 Control strategies for responding to system failures, e.g. for fault diagnosis, failsafe operation or limp mode
• CPC Class Codes: B60W 2530/12 Catalyst or filter state
• CPC Class Codes: B60W 2530/209 Fuel quantity remaining in tank
• CPC Class Codes: B60W 2540/06 Ignition switch
• CPC Class Codes: B60W 2555/20 Ambient conditions, e.g. wind or rain
• CPC Class Codes: F02D 41/0035 to achieve a special effect, e.g. to warm up the catalyst
• 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: F02M 25/0809 Judging failure of purge control system
• CPC Class Codes: F02M 37/0076 Details of the fuel feeding system related to the fuel tank vehicle fuel tanks B60K15/03
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y10S 903/905 Combustion engine

Abstract

Methods and systems for fuel system leak detection are disclosed. In one example approach, a method comprises, during an engine-on condition, delivering fuel from a fuel tank to one or more cylinders of the engine while the fuel tank is sealed off from atmosphere, and indicating a leak based on pressure in the fuel tank. For example, a leak may be indicated in response to a pressure decrease in the fuel tank greater than an expected pressure decrease, where the expected pressure decrease is based on a fuel level in the fuel tank.

Claims

1. A method for a vehicle with an engine, comprising:

during an engine-on condition, delivering fuel from a fuel tank to one or more cylinders of the engine while the fuel tank is sealed off from atmosphere; and

indicating a leak based on pressure in the fuel tank.

2. The method of claim 1, further comprising indicating a leak in response to a pressure decrease in the fuel tank greater than an expected pressure decrease, where the expected pressure decrease is based on a fuel level in the fuel tank.

3. The method of claim 2, wherein the expected pressure decrease is further based on a temperature in the fuel tank, and wherein the delivering of fuel includes delivering fuel to all engine cylinders at a fuel flow rate above a non-zero upper threshold.

4. The method of claim 3, wherein the expected pressure decrease is further based on an ambient temperature.

5. The method of claim 2, wherein the expected pressure decrease is obtained from a lookup table based on a temperature in the fuel tank and fuel level in the fuel tank.

6. The method of claim 1, further comprising indicating a leak based on a rate of pressure decrease in the fuel tank greater than a threshold rate of pressure decrease.

7. The method of claim 6, wherein the threshold rate of pressure decrease is based on a fuel level in the fuel tank and a temperature in the fuel tank.

8. The method of claim 1, further comprising determining a size of the leak based on a rate of pressure decrease in the fuel tank.

9. The method of claim 1, further comprising determining a size of the leak based on a comparison of a pressure in the fuel tank with an expected pressure, where the expected pressure is based on a fuel level in the fuel tank and a temperature in the fuel tank.

10. The method of claim 1, further comprising, during an engine-off condition subsequent to the engine-on condition, indicating a leak based on a pressure in the fuel tank less than a threshold pressure.

11. The method of claim 1, further comprising, indicating a leak based on a rate of pressure decrease in the fuel tank greater than a threshold rate of decrease following an engine-off event subsequent to the engine-on condition.

12. The method of claim 1, further comprising indicating a leak based on a pressure in the fuel tank less than a threshold during an engine-on event where the engine-on event is subsequent to an engine-off condition following the engine-on condition.

13. The method of claim 12, wherein the engine-on event is a key-on event

14. A method for a vehicle with an engine and an evaporative emissions control system, comprising:

while operating the engine, delivering fuel from a fuel tank to the engine while the fuel tank is sealed off from atmosphere; and

indicating a leak in the evaporative emissions control system based on a pressure decrease in the fuel tank greater than an expected pressure decrease, where the expected pressure decrease is based on a fuel level in the fuel tank

15. The method of claim 14, wherein the fuel level in the fuel tank is based on a fuel level reading of a fuel level sensor in the fuel tank, and where the fuel tank is sealed from the engine intake and any other gas port.

16. The method of claim 14, further comprising determining a size of the leak based on a comparison of the pressure decrease in the fuel tank with the expected pressure decrease.

17. The method of claim 14, wherein the vehicle is a plug-in hybrid electric vehicle.

18. A method for a vehicle with an engine, comprising:

during an engine-on condition, delivering fuel from a fuel tank to one or more cylinders of the engine while the fuel tank is sealed off from atmosphere; and

during an engine-off condition subsequent to the engine-on condition, maintaining the fuel tank sealed off from the atmosphere and indicating a leak in response to a pressure decrease in the fuel tank greater than an expected pressure decrease, where the expected pressure decrease is based on a fuel level in the fuel tank.

19. The method of claim 18, wherein the expected pressure decrease is further based on a temperature in the fuel tank.

20. The method of claim 18, further comprising determining a size of the leak based on a comparison of the pressure decrease in the fuel tank with the expected pressure decrease.