EVAPORATIVE EMISSIONS SYSTEM AND METHOD FOR A STOP/START VEHICLE

• US 20160053726A1
• Filed: 08/25/2014
• Published: 02/25/2016
• Est. Priority Date: 08/25/2014
• 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.
• Granted Patent: US 9,797,348 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: F02M 25/0809 Judging failure of purge control system
• CPC Class Codes: F02M 25/0836 Arrangement of valves controlling the admission of fuel vapour to an engine, e.g. valve being disposed between fuel tank or absorption canister and intake manifold
• CPC Class Codes: F02M 25/089 Layout of the fuel vapour installation

Abstract

Systems and methods for diagnosing individual components of an evaporative emissions system are presented. In one example, fuel vapor flow may be a basis for determining whether or not selected emission system components may be degraded. Further, fuel tank pressure may be another basis for determining component whether or not selected emissions system components may be degraded.

Claims

1. A method, comprising:

responsive to selected conditions, commanding close a fuel vapor blocking valve while opening a canister vent valve and a canister purge valve;

indicating a degradation of the canister vent valve or the canister purge valve responsive to a fuel vapor flow not decreasing while the canister purge valve is exposed to a threshold vacuum; and

adjusting an actuator in response to indicating the degradation.

2. The method of claim 1, where the actuator is the canister vent valve when the canister purge valve is determined degraded, and where the canister vent valve is held closed.

3. The method of claim 2, further comprising opening the canister vent valve in response to a pressure in a fuel tank exceeding a threshold pressure.

4. The method of claim 1, where the actuator is a light or a display panel.

5. The method of claim 1, where indicating the canister vent valve is degraded is in further response to a fuel tank pressure less than a threshold pressure, and further comprising commanding opening of a vapor blocking valve prior to determining the canister vent valve is degraded.

6. The method of claim 1, where the canister purge valve is indicated degraded in further response to a fuel tank pressure being within a predetermined pressure of atmospheric pressure, and further comprising commanding opening of a vapor blocking valve prior to determining the canister vent valve is degraded.

7. The method of claim 1, where the selected conditions include the vehicle cruising.

8. A method, comprising:

responsive to selected conditions, commanding close a fuel vapor blocking valve while opening a canister vent valve and a canister purge valve;

indicating a degradation of the canister vent valve or the canister purge valve responsive to a fuel vapor flow not decreasing while the canister purge valve is exposed to a threshold vacuum;

otherwise, commanding close the canister vent valve, opening the canister vent valve, and opening the fuel vapor blocking valve;

indicating a degradation of the fuel vapor blocking valve responsive to the fuel vapor flow not increasing while the canister purge valve is exposed to a threshold vacuum; and

adjusting an actuator in response to degradation of the canister vent valve, the canister purge valve, or the fuel vapor blocking valve.

9. The method of claim 8, where the canister vent valve is positioned along a conduit providing fluidic communication between a fuel vapor storage canister and atmosphere, where the canister purge valve is positioned along a conduit providing fluidic communication between an engine and the fuel vapor storage canister, and where the fuel vapor blocking valve is positioned along a conduit between a fuel tank and the fuel vapor storage canister.

10. The method of claim 9, where the actuator is the canister vent valve when the canister purge valve is determined degraded, and where the canister vent valve is held closed.

11. The method of claim 10, further comprising opening the canister vent valve in response to a pressure in a fuel tank exceeding a threshold pressure.

12. The method of claim 8, where the actuator is a light or a display panel.

13. The method of claim 8, where the selected conditions include a vehicle refueling event.

14. The method of claim 8, further comprising indicating a partially restricted canister purge valve or a partially restricted fuel vapor blocking valve in further response to fuel tank pressure not less than a threshold pressure when commanding the fuel vapor blocking valve closed, the canister purge valve open, and the canister vent valve open.

15. A method, comprising:

responsive to selected conditions, commanding close a fuel vapor blocking valve while opening a canister vent valve and a canister purge valve;

indicating a degradation of the canister vent valve or the canister purge valve responsive to a fuel vapor flow estimate not decreasing while the canister vent valve is exposed to a threshold vacuum;

otherwise, commanding open the fuel vapor blocking valve, opening the canister purge valve, and closing the canister vent valve;

indicating excess flow in an evaporative emissions system responsive to the fuel vapor flow estimate increasing; and

adjusting an actuator in response to degradation of the canister vent valve, the canister purge valve, or the indication of excess flow.

16. The method of claim 15, where the actuator is a light or a display panel.

17. The method of claim 15, further comprising indicating fuel vapor blocking valve degradation responsive to the fuel vapor flow estimate not increasing while the fuel vapor blocking valve is commanded open, the canister purge valve is commanded open, and the canister vent valve is commanded closed.

18. The method of claim 15, where the selected conditions include a vehicle refueling event.

19. The method of claim 15, further comprising indicating the excess flow in the evaporative emissions system responsive to fuel tank pressure not being less than a threshold value.

20. The method of claim 19, further comprising performing a leak diagnostic in response to the fuel tank pressure being less than the threshold value.