ENGINE-OFF LEAK DETECTION BASED ON PRESSURE

• US 20150046026A1
• Filed: 08/08/2013
• Published: 02/12/2015
• Est. Priority Date: 08/08/2013
• Status: Abandoned Application

• 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., Yang, Dennis Seung-Man, Dudar, Aed M.
• Application Number:
  US13/962,562
• Publication Number:
  US 20150046026A1
• Time in Patent Office: Days
• US Class Current: 701/33.9
• CPC Class Codes: G07C 5/00 Registering or indicating the working of vehicles
• CPC Class Codes: Y10S 903/903 having energy storing means, e.g. battery, capacitor

Abstract

Methods and systems for fuel system leak detection are disclosed. In one example approach, a method comprises, in response to a pressure change in a fuel tank less than a threshold for a duration during engine-off conditions while the tank is sealed off from atmosphere, indicating a leak condition, and in response to a pressure change in the tank greater than the threshold during engine-off conditions while the tank is sealed off from atmosphere, indicating a no-leak condition.

Claims

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

in response to a pressure change in a fuel tank less than a threshold for a duration during engine-off conditions while the tank is sealed off from atmosphere, indicating a leak condition; and

in response to a pressure change in the tank greater than the threshold during engine-off conditions while the tank is sealed off from atmosphere, indicating a no-leak condition.

2. The method of claim 1, wherein the duration is time duration during which temperature of the fuel tank changes by a threshold amount.

3. The method of claim 1, wherein the engine-off conditions occur during vehicle operation.

4. The method of claim 1, wherein the engine-off conditions occur during vehicle operation while the vehicle is in motion.

5. The method of claim 1, wherein the vehicle is a hybrid electric vehicle.

6. The method of claim 1, wherein the pressure change is a change in pressure from atmospheric pressure.

7. The method of claim 1, further comprising indicating a no-leak condition in response to a pressure increase in the fuel tank greater than a threshold during increasing temperature conditions in the fuel tank and indicating a leak condition in response to a pressure increase in the fuel tank less than the threshold for a duration during increasing temperature conditions in the fuel tank.

8. The method of claim 1, further comprising indicating a no-leak condition in response to a pressure decrease in the fuel tank greater than a threshold during decreasing temperature conditions in the fuel tank and indicating a leak condition in response to a pressure decrease in the fuel tank less than the threshold for a duration during decreasing temperature conditions in the fuel tank.

9. The method of claim 1, wherein the fuel tank is sealed off from an engine intake and any other gas port during the engine-off conditions.

10. A method for a hybrid electric vehicle with an engine, comprising:

during engine-off conditions while a fuel tank is sealed off from an engine intake and any other gas port, indicating a leak in response to a pressure change in the fuel tank less than a threshold for a duration.

11. The method of claim 10, further comprising, during engine-off conditions while the fuel tank is sealed off from the engine intake and any other gas port, indicating a no-leak condition in response to a pressure change in the fuel tank greater than the threshold.

12. The method of claim 10, wherein the duration is time duration during which temperature of the fuel tank changes by a threshold amount.

13. The method of claim 10, wherein the engine-off conditions occur during vehicle operation while the vehicle is in motion.

14. The method of claim 10, wherein the pressure change is a change in pressure from atmospheric pressure.

15. The method of claim 10, further comprising indicating a no-leak condition in response to a pressure increase in the fuel tank greater than a threshold during increasing temperature conditions in the fuel tank and indicating a leak condition in response to a pressure increase in the fuel tank less than the threshold for a duration during increasing temperature conditions in the fuel tank.

16. The method of claim 10, further comprising indicating a no-leak condition in response to a pressure decrease in the fuel tank greater than a threshold during decreasing temperature conditions in the fuel tank and indicating a leak condition in response to a pressure decrease in the fuel tank less than the threshold for a duration during decreasing temperature conditions in the fuel tank.

17. A method for a hybrid electric vehicle with an engine, comprising:

during engine-off conditions while a fuel tank is sealed off from an engine intake, atmosphere, and any other gas port, indicating a leak in response to a pressure change in the fuel tank less than a threshold for a duration, where the duration is a time duration during which temperature of the fuel tank changes by a threshold amount; and

during engine-off conditions while the fuel tank is sealed off from the engine intake and any other gas port, indicating a no-leak condition in response to a pressure change in the fuel tank greater than the threshold.

18. The method of claim 17, wherein the pressure change is a change in pressure from atmospheric pressure.

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

20. The method of claim 17, wherein the engine-off conditions occur during vehicle operation while the vehicle is in motion.