Systems and methods for detection and mitigation of liquid fuel carryover in an evaporative emissions system

• US 10,040,448 B2
• Filed: 11/12/2015
• Issued: 08/07/2018
• Est. Priority Date: 11/12/2015
• 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.
• Primary Examiner(s): Antonucci, Anne M
• Assistant Examiner(s): Malhotra, Sanjeev
• Application Number:
  US14/939,672
• Publication Number:
  US 20170137022A1
• Time in Patent Office: 999 Days
• Field of Search: 123516, 123519, 123520, 141 1, 141 59, 141198, 475128, 475221, 137202, 137588, 62 481, 62 491, 95 90
• CPC Class Codes: B60K 15/03 Fuel tanks chassis frame comprising fluid storage compartment B62D21/16 ; Details of the fuel feeding system related to the fuel tank F02M37/0076
• CPC Class Codes: B60K 2006/268 Electric drive motor starts the engine, i.e. used as starter motor
• CPC Class Codes: B60K 2015/0319 with electronic systems, e.g. for controlling fuelling or venting for LPG tanks B60K2015/03013
• CPC Class Codes: B60K 2015/03217 Fuel level sensors
• CPC Class Codes: B60K 2015/03296 Pressure regulating valves
• CPC Class Codes: B60K 2015/03328 Arrangements or special measures related to fuel tanks or fuel handling
• CPC Class Codes: B60K 6/20 the prime-movers consisting of electric motors and internal combustion engines, e.g. HEVs
• CPC Class Codes: B60K 6/24 characterised by the combustion engines
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 20/50 Control strategies for responding to system failures, e.g. for fault diagnosis, failsafe operation or limp mode
• CPC Class Codes: B60W 2530/00 Input parameters relating to vehicle conditions or values, not covered by groups B60W2510/00 or B60W2520/00
• CPC Class Codes: B60W 50/14 Means for informing the driver, warning the driver or prompting a driver intervention
• CPC Class Codes: B60Y 2200/92 Hybrid vehicles
• CPC Class Codes: F02D 13/0203 Variable control of intake and exhaust valves
• CPC Class Codes: F02D 15/00 Varying compression ratio
• 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 25/089 Layout of the fuel vapour installation
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles
• CPC Class Codes: Y10S 903/905 : Combustion engine
• CPC Class Codes: Y10S 903/93 : Conjoint control of different elements
• CPC Class Codes: Y10S 903/951 : Assembly or relative location of components

Abstract

Methods and systems are provided for detecting and mitigating the presence of liquid fuel carryover in an evaporative emissions control system of a vehicle in response to a refueling event. In one example, an electric motor is operated to spin a vehicle engine unfueled in reverse in order to pressurize the evaporative emissions system and the fuel system responsive to an indication of liquid fuel in the vapor recovery lines. In this way, indication of liquid fuel carryover following a refueling event may be quickly diagnosed, and mitigating actions may be taken to ensure liquid fuel is returned to the tank prior to contacting the adsorbent material within the vapor canister.

Claims

1. A method comprising:

during refueling a tank which supplies fuel to a combustion engine, venting the tank to atmosphere through a vapor storage system; and

after refueling and when pressure decay in the tank is less than a threshold, sealing the vapor storage system from atmosphere and running the engine un-fueled in reverse with an electric motor to force air from an intake manifold of the engine through the vapor storage system into the tank, wherein pressure decay in the tank after refueling comprises a first pressure decay rate, and wherein pressure decay in the tank while running the engine in reverse comprises a second pressure decay rate; and

further comprising continuing to run the engine in reverse until pressure in the tank decreases to atmospheric pressure when the second pressure decay rate is greater than another threshold.

2. The method of claim 1, further comprising:

coupling and uncoupling the tank to the vapor storage system through a fuel tank isolation valve;

selectively coupling the intake manifold of the engine to atmosphere through a throttle;

selectively coupling a vapor storage canister in the vapor storage system to the intake manifold of the engine through a canister purge valve; and

selectively coupling the vapor storage canister to atmosphere through a canister vent valve;

wherein running the engine un-fueled in reverse further comprises opening the fuel tank isolation valve, closing the throttle, opening the canister purge valve, and closing the canister vent valve.

3. The method of claim 2, further comprising:

purging fuel vapors stored in a vapor adsorbent, which is housed in the vapor storage canister, into the intake manifold under predetermined engine operating conditions; and

said purging further comprising;

commanding open the canister purge valve, maintaining closed the fuel tank isolation valve, and commanding open or maintaining open the canister vent valve to direct air through the vapor storage system to the intake manifold to purge the vapor storage system and a fuel vapor canister of hydrocarbons.

4. The method of claim 3, further comprising:

responsive to a second pressure decay rate being less than the threshold, deactivating spinning the engine in reverse; and

indicating a restriction in the vapor storage system.

5. The method of claim 4, further comprising:

responsive to indicating the restriction in the vapor storage system, suspending purging of the fuel vapor canister at a subsequent engine-on event.

6. The method of claim 1, further comprising:

responsive to the second pressure decay rate being greater than a threshold, determining whether the refueling included an automatic shutoff of a refueling dispenser which is temporarily coupled to the tank; and

responsive to determining that the refueling did not include the automatic shutoff of the refueling dispenser, indicating to perform one or more on-board tests to determine an operating condition of a fuel system which includes the tank.

7. The method of claim 6, further comprising:

responsive to determining that the refueling did include the automatic shutoff of the refueling dispenser, determining whether a fuel level indicator housed within the tank indicates that the tank is full; and

responsive to determining that the fuel level indicator indicates that the tank is full, indicating that the tank was overfilled.

8. The method of claim 7, further comprising:

responsive to determining that the fuel level indicator indicates that the tank is not full, indicating an on-board test to determine an operating condition of the fuel level indicator.

9. A method comprising:

during refueling a tank which supplies fuel to a combustion engine, venting the tank to atmosphere through a vapor storage system;

after refueling and when pressure decay in the tank is less than a threshold, sealing the vapor storage system from atmosphere and running the engine un-fueled in reverse with an electric motor to force air from an intake manifold of the engine through the vapor storage system into the tank;

coupling and uncoupling the tank to the vapor storage system through a fuel tank isolation valve;

selectively coupling the intake manifold of the engine to atmosphere through a throttle;

selectively coupling a vapor storage canister in the vapor storage system to the intake manifold of the engine through a canister purge valve; and

selectively coupling the vapor storage canister to atmosphere through a canister vent valve;

wherein running the engine un-fueled in reverse further comprises opening the fuel tank isolation valve, closing the throttle, opening the canister purge valve, and closing the canister vent valve.

10. The method of claim 9, wherein pressure decay in the tank after refueling comprises a first pressure decay rate, and wherein pressure decay in the tank while running the engine in reverse comprises a second pressure decay rate;

and further comprising continuing to run the engine in reverse until pressure in the tank decreases to atmospheric pressure when the second pressure decay rate is greater than another threshold.

11. The method of claim 10, further comprising:

responsive to the second pressure decay rate being greater than a threshold, determining whether the refueling included an automatic shutoff of a refueling dispenser which is temporarily coupled to the tank; and

responsive to determining that the refueling did not include the automatic shutoff of the refueling dispenser, indicating to perform one or more on-board tests to determine an operating condition of a fuel system which includes the tank.

12. The method of claim 11, further comprising:

responsive to determining that the refueling did include the automatic shutoff of the refueling dispenser, determining whether a fuel level indicator housed within the tank indicates that the tank is full; and

responsive to determining that the fuel level indicator indicates that the tank is full, indicating that the tank was overfilled.

13. The method of claim 12, further comprising:

responsive to determining that the fuel level indicator indicates that the tank is not full, indicating an on-board test to determine an operating condition of the fuel level indicator.

14. The method of claim 13, further comprising:

responsive to a second pressure decay rate being less than the threshold, deactivating spinning the engine in reverse; and

indicating a restriction in the vapor storage system.

15. The method of claim 14, further comprising:

responsive to indicating the restriction in the vapor storage system, suspending purging of the fuel vapor canister at a subsequent engine-on event.

16. The method of claim 9, further comprising:

purging fuel vapors stored in a vapor adsorbent, which is housed in the vapor storage canister, into the intake manifold under predetermined engine operating conditions; and

said purging further comprising;

commanding open the canister purge valve, maintaining closed the fuel tank isolation valve, and commanding open or maintaining open the canister vent valve to direct air through the vapor storage system to the intake manifold to purge the vapor storage system and a fuel vapor canister of hydrocarbons.