METHOD AND SYSTEM FOR ADJUSTING A FUEL TANK ISOLATION VALVE

• US 20150122229A1
• Filed: 09/25/2014
• Published: 05/07/2015
• Est. Priority Date: 11/06/2013
• 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, Jentz, Robert Roy, Aitken, Brian Thomas, Ognjanovski, Robert Jr.
• Granted Patent: US 9,518,677 B2
• Time in Patent Office: Days
• US Class Current: 123/518
• CPC Class Codes: F02D 41/0032 Controlling the purging of the canister as a function of the engine operating conditions
• CPC Class Codes: F02M 2025/0845 Electromagnetic valves
• CPC Class Codes: F02M 25/0818 having means for pressurising the evaporative emission space
• 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: F16K 37/0041 for measuring valve parameters F16K37/0033 takes precedence

Abstract

Methods and systems are provided for adjusting and diagnosing a position of a fuel tank isolation valve (FTIV) of a fuel system. In one example, a method comprises adjusting a FTIV of a fuel system by sending an electrical pulse to the FTIV; and comparing a current draw of the FTIV to a known current draw profile to verify the position of the FTIV. In this way, the position of the FTIV may be diagnosed, thereby resulting in increased accuracy of subsequent valve control.

Claims

1. An engine method, comprising:

adjusting a fuel tank isolation valve (FTIV) of a fuel system by sending an electrical pulse to the FTIV; and

comparing a current draw of the FTIV to a known current draw profile to verify the position of the FTIV.

2. The method of claim 1, wherein the known current draw profile is an open current draw profile and the position of the FTIV is open when the current draw of the FTIV matches the open current draw profile.

3. The method of claim 2, wherein the open current draw profile includes a current draw peak indicating the FTIV is moving from a closed valve position to an intermediate valve position and a subsequent current draw plateau indicating the FTIV is held in the intermediate valve position, the current draw peak and the subsequent current draw plateau occurring within the duration of the electrical pulse.

4. The method of claim 1, wherein the known current draw profile is a closed current draw profile and the position of the FTIV is closed when the current draw of the FTIV matches the closed current draw profile.

5. The method of claim 4, wherein the closed current draw profile includes a current draw plateau occurring within the duration of the electrical pulse.

6. The method of claim 1, further comprising adjusting the FTIV by sending the electrical pulse to the FTIV in response to one or more of the position of the FTIV being unknown, a duration since a last FTIV position diagnosis, or the position of the FTIV being invalidated.

7. The method of claim 1, wherein verifying the position of the FTIV includes verifying that the FTIV is open responsive to an expected position of the FTIV being an open position.

8. The method of claim 7, further comprising sending an electrical pulse to actuate the FTIV in response to verifying that the FTIV is open when the expected position of the FTIV is a closed position.

9. The method of claim 1, further comprising indicating a degradation of an FTIV shaft in response to the current draw not matching the known current draw profile while the FTIV is drawing current when the electrical pulse is sent to the FTIV.

10. The method of claim 1, further comprising indicating a degradation of an FTIV solenoid in response to the FTIV not drawing current when the electrical pulse is sent to the FTIV.

11. The method of claim 1, wherein adjusting the FTIV includes sending one of the electrical pulses to actuate the FTIV from a first position to a desired position.

12. The method of claim 1, wherein the FTIV is a bi-stable valve coupled between a fuel tank and a canister of the fuel system.

13. A method, comprising:

adjusting a fuel tank isolation valve (FTIV) of a fuel system by sending electrical pulses to the FTIV;

counting each of the electrical pulses to track a position of the FTIV; and

using a canister temperature to verify the position of the FTIV when the position of the FTIV is unknown or invalid.

14. The method of claim 13, wherein using the canister temperature to verify the position of the FTIV comprises indicating the FTIV is open responsive to the canister temperature increasing above a threshold within a duration and indicating the FTIV is closed otherwise.

15. The method of claim 13, wherein using the canister temperature to verify the position of the FTIV comprises applying a vacuum to the engine fuel system and verifying the position of the FTIV based on changes to the canister temperature.

16. The method of claim 15, wherein applying the vacuum includes operating a vacuum pump of an evaporative leak check module positioned in the engine fuel system.

17. A fuel system, comprising:

an engine;

a fuel tank;

a canister for storing fuel vapors;

a fuel tank isolation valve (FTIV) coupled in a vapor line between the fuel tank and the canister, the FTIV held in both opened and closed positions without any applied current; and

a controller with computer readable instructions for diagnosing a position of the FTIV and subsequently adjusting the FTIV based on the diagnosed position and engine operating conditions.

18. The system of claim 17, wherein diagnosing the position of the FTIV comprises comparing a current draw of the FTIV to known current draw profiles to determine if the FTIV is open, closed, or degraded.

19. The system of claim 17, wherein diagnosing the position of the FTIV includes setting a known position of the FTIV as a closed position when one or more of a pressure of the fuel tank increases above a threshold pressure or decreases below a vacuum threshold pressure.

20. The system of claim 17, further comprising a temperature sensor coupled to the canister, and wherein diagnosing the position of the FTIV includes setting a known position of the FTIV as an open position when a temperature of the canister increases above a threshold temperature within a time duration.