Method and system for adjusting a fuel tank isolation valve

Patent metadata

Field	Value
Publication number	US-9464601-B2
Application number	US-201314073750-A
Country	US
Kind code	B2
Filing date	Nov 6, 2013
Priority date	Nov 6, 2013
Publication date	Oct 11, 2016
Grant date	Oct 11, 2016

Abstract

Methods and systems are provided for adjusting and diagnosing a position of a fuel tank isolation valve of a fuel system. In one example, a method may include adjusting the fuel tank isolation valve via electrical pulses and tracking a position of the FTIV by counting each of the electrical pulses. When a vacuum is created in the fuel system, the method may include verifying the position of the FTIV based on resulting fuel system pressures.

First claim

The invention claimed is:

1. An engine method, comprising:
via a controller:
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;
applying a vacuum to force the FTIV to a known closed position;
verifying the closed position of the FTIV in response to sensing the applied vacuum in the fuel system; and
following verification, actuating the FTIV to a desired position based on the verified position and engine operating conditions by sending further electrical pulses.

2. The method of claim 1 , further comprising generating an indication of the verified position, the method further comprising taking a default action in response to the indication of the verified position.

3. The method of claim 1 , further comprising verifying the FTIV is closed in response to a fuel tank pressure greater than a threshold pressure.

4. The method of claim 1 , further comprising applying the vacuum to the fuel system in response to one or more of the position of the FTIV being unknown, a duration since a last FTIV position diagnosis, or a request to run a leak detection routine.

5. The method of claim 4 , wherein applying the vacuum to the fuel system includes operating a vacuum pump coupled to a vent of a canister of the fuel system to apply a negative pressure to the fuel system.

6. The method of claim 4 , wherein verifying the closed position of the FTIV includes verifying that the FTIV is open responsive to an expected position of the FTIV being an open position and no vacuum being sensed after applying the vacuum.

7. The method of claim 6 , 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 the closed position.

8. The method of claim 6 , further comprising reapplying the vacuum to the fuel system after sending the electrical pulse and indicating degradation of the FTIV if no vacuum is sensed after reapplying the vacuum.

9. 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 the desired position.

10. The method of claim 9 , further comprising not sending the one of the electrical pulses to actuate the FTIV when the FTIV is already in the desired position.

11. 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 and wherein verifying the closed position includes verifying the closed position of the FTIV in response to sensing fuel system pressure decreasing below a vacuum threshold pressure, where the vacuum threshold pressure is a pressure at which vacuum is created.

12. A method for an engine fuel system, comprising:
via a controller: tracking a position of a fuel tank isolation valve (FTIV); and
during a first condition when the position of the FTIV is known, adjusting the position of the FTIV based on engine operating conditions from the known position; and
during a second condition when the position of the FTIV is unknown, applying a vacuum to the engine fuel system and the FTIV to force the FTIV to a known closed position and verifying the closed position of the FTIV based on detection of the vacuum.

13. The method of claim 12 , wherein applying the vacuum includes operating a vacuum pump of an evaporative leak check module positioned in the engine fuel system to create the vacuum.

14. The method of claim 12 , wherein verifying the closed position of the FTIV includes, after applying the vacuum, verifying the FTIV is closed in response to an engine fuel system pressure being less than a vacuum threshold pressure and verifying the FTIV is open in response to the engine fuel system pressure being greater than the vacuum threshold pressure.

15. The method of claim 12 , further comprising, after moving the FTIV to the closed position,
sending an electrical pulse to actuate the FTIV into an open position, from the closed position, in response to a request to open the FTIV; and
not sending an electrical pulse to actuate the FTIV in response to a request to close the FTIV.

16. The method of claim 12 , further comprising adjusting the FTIV into an open position during one or more of refueling events or during purging events wherein a fuel tank pressure increases above a threshold pressure and adjusting the FTIV into the closed position during leak detection routines.

17. The method of claim 12 , wherein adjusting the FTIV includes sending an electrical pulse to actuate the FTIV and wherein tracking the position of the FTIV includes counting a number of actuations of the FTIV and updating the known position after each actuation.

18. 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;
a leak check module including a reference orifice, a vacuum pump, and a pressure sensor; and
a controller with computer readable instructions for:
applying a vacuum to the fuel system via the vacuum pump to force the FTIV to a known closed position; and
diagnosing the closed position of the FTIV based on fuel system pressure after applying the vacuum and subsequently adjusting the FTIV based on the diagnosed position and engine operating conditions.

19. The system of claim 18 , wherein diagnosing the closed position of the FTIV includes setting a known position of the FTIV as the 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 18 , wherein the computer readable instructions further include instructions for adjusting the vacuum pump to apply the vacuum to the fuel system in response to a request to operate the vacuum pump and wherein the request to operate the vacuum pump is generated in response to one or more of a first amount of time passing since diagnosing the closed position of the FTIV, a second amount of time passing since performing a leak test, or a fuel system event resulting in uncertainty of the FTIV position.

Assignees

• Ford Global Tech Llc

Inventors

• Bolger Bryan
• Lindlbauer Michael Paul
• Peters Mark W

Classifications

• F02D2041/224

  Diagnosis of the fuel system · CPC title

• F02M25/0818

  having means for pressurising the evaporative emission space · CPC title

• F02D41/221

  relating to the failure of actuators or electrically driven elements · CPC title

• F02D41/004

  Control of the valve or purge actuator, e.g. duty cycle, closed loop control of position · CPC title

• F02D2041/228

  Warning displays · CPC title