LEAK DETECTION FOR CANISTER PURGE VALVE

• US 20150019066A1
• Filed: 07/10/2013
• Published: 01/15/2015
• Est. Priority Date: 07/10/2013
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Dudar, Aed M., Yang, Dennis Seung-Man
• Granted Patent: US 9,255,553 B2
• Time in Patent Office: Days
• US Class Current: 701/29.7
• CPC Class Codes: F02D 2041/225 Leakage detection
• CPC Class Codes: F02D 2200/0606 Fuel temperature
• CPC Class Codes: F02D 29/02 peculiar to engines driving vehicles; peculiar to engines driving variable pitch propellers
• CPC Class Codes: F02D 41/0035 to achieve a special effect, e.g. to warm up the catalyst
• CPC Class Codes: F02M 25/0809 Judging failure of purge control system

Abstract

Methods and systems for detecting a leak in a canister purge valve are disclosed. In one example approach, a method comprises indicating a leak in response to a temperature change in a fuel vapor canister coupled to a fuel tank in an emission control system while the engine is in operation and a purge valve is closed.

Claims

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

indicating a leak in response to a temperature change in a fuel vapor canister coupled to a fuel tank in an emission control system while the engine is in operation and a purge valve is closed.

2. The method of claim 1, wherein the temperature change comprises a temperature decrease in the canister.

3. The method of claim 1, wherein the temperature change comprises a temperature decreasing below a threshold temperature.

4. The method of claim 1, wherein the temperature change comprises a rate of temperature decrease in the canister greater than a threshold.

5. The method of claim 1, wherein indicating a leak in response to a temperature change in the fuel vapor canister is performed in response to a fault in a pressure sensor coupled to the fuel tank.

6. The method of claim 1, wherein indicating a leak is further responsive to a pressure sensor coupled to the fuel tank.

7. The method of claim 1, wherein indicating a leak response to a pressure sensor coupled to the fuel tank comprises indicating a leak in response to a pressure decrease in the fuel tank while the engine is in operation and a purge valve is closed.

8. The method of claim 1, wherein the purge valve is disposed in a conduit coupling the canister to an intake of the engine.

9. The method of claim 1, wherein the temperature change is compensated for one or more of an ambient temperature, a fuel type, and an altitude.

10. The method of claim 1, wherein the fuel vapor canister contains activated charcoal.

11. A method for a vehicle with an engine comprising:

during engine-on conditions;

closing or maintaining a purge valve closed; and

indicating a leak in response to a temperature change in a fuel vapor canister coupled to a fuel tank in an emission control system.

12. The method of claim 11, wherein the temperature change comprises a temperature decreasing below a threshold temperature.

13. The method of claim 11, wherein the temperature change comprises a rate of temperature decrease in the canister greater than a threshold.

14. The method of claim 11, wherein indicating a leak in response to a temperature change in the fuel vapor canister comprises indicating a leak in the purge valve.

15. The method of claim 11, wherein indicating a leak in response to response to a temperature change in the fuel vapor canister is performed in response to a fault in a pressure sensor coupled to the fuel tank.

16. The method of claim 11, wherein indicating a leak is further responsive to a pressure decrease in the fuel tank while the engine is in operation and the purge valve is closed.

17. The method of claim 11, wherein during the engine-on conditions, the fuel tank is completely sealed off from atmosphere.

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

indicating a leak in response to a temperature decrease in a fuel vapor canister coupled to a fuel tank in an emission control system while the engine is in operation and a purge valve is closed, where the purge valve is disposed in a conduit coupling the canister to an intake of the engine.

19. The method of claim 18, wherein the temperature decrease comprises a temperature decrease below a threshold temperature.

20. The method of claim 18, wherein indicating a leak in response to a temperature decrease in the fuel vapor canister is performed in response to a fault in a pressure sensor coupled to the fuel tank.