Systems and methods for limited emissions refueling

• US 10,371,102 B2
• Filed: 10/20/2016
• Issued: 08/06/2019
• Est. Priority Date: 02/02/2016
• 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): Maust, Timothy L
• Assistant Examiner(s): Hakomaki, James R
• Application Number:
  US15/299,256
• Publication Number:
  US 20170218885A1
• Time in Patent Office: 1,020 Days
• Field of Search: 141 5
• CPC Class Codes: B01D 2257/7022 Aliphatic hydrocarbons
• CPC Class Codes: B01D 2259/4516 for fuel vapour recovery systems
• CPC Class Codes: F02D 41/0042 Controlling the combustible mixture as a function of the canister purging, e.g. control of injected fuel to compensate for deviation of air fuel ratio when purging
• 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: G06Q 30/018 Certifying business or products
• CPC Class Codes: G06Q 50/06 Energy or water supply

Abstract

A method is presented, comprising, during a first condition, including an active refueling event, receiving an indication of hydrocarbon breakthrough from the fuel vapor canister; and flowing refueling vapors into an intake manifold responsive to the indication of hydrocarbon breakthrough. Flowing refueling vapors into an intake manifold traps the vapors there until engine start-up, when the vapor can be combusted by the engine. In this way, refueling emissions may be reduced, even if the fuel vapor canister is saturated prior to, or during the refueling event.

Claims

1. A method for a vehicle, comprising:

during a first condition, including an ongoing refueling event where a fuel filler neck is accessible, receiving an indication of hydrocarbon breakthrough from a fuel vapor canister; and

flowing refueling vapors into an intake manifold and maintaining access to the fuel filler neck responsive to the indication of hydrocarbon breakthrough, the refueling vapors trapped in the intake manifold until an engine start-up.

2. The method of claim 1, further comprising:

updating one or more engine start-up parameters following termination of the refueling event based on the refueling vapors trapped in the intake manifold.

3. The method of claim 2, wherein the one or more engine start-up parameters comprise a fuel injection quantity at the engine start-up.

4. The method of claim 1, wherein flowing refueling vapors into the intake manifold comprises opening a canister purge valve coupled between the fuel vapor canister and the intake manifold.

5. The method of claim 4, wherein flowing refueling vapors into the intake manifold further comprises duty-cycling a canister vent valve coupled between the fuel vapor canister and atmosphere.

6. The method of claim 4, further comprising isolating unbound fuel vapors following termination of the refueling event.

7. The method of claim 6, wherein isolating unbound fuel vapors comprises closing the canister purge valve.

8. The method of claim 1, wherein the indication of hydrocarbon breakthrough from the fuel vapor canister comprises an output of a hydrocarbon sensor coupled within a fuel vapor canister vent pathway, between a fresh air port and a canister vent valve, increasing above a threshold.

9. The method of claim 1, further comprising:

receiving a request for a refueling event;

responsive to the request, depressurizing a fuel tank by opening a fuel tank isolation valve coupled between a fuel and the fuel vapor canister while maintaining access restrictions to the fuel filler neck; and

granting access to the fuel filler neck responsive to an absolute fuel tank pressure decreasing below a threshold.

10. The method of claim 9, wherein the first condition comprises limited emission refueling parameters being activated.

11. The method of claim 10, further comprising:

during a second condition, including an active refueling event, restricting flow of refueling vapors into the intake manifold regardless of the indication of hydrocarbon breakthrough, including even when the indication of hydrocarbon breakthrough is generated.

12. The method of claim 11, wherein the limited emission refueling parameters are inactive during the second condition.

13. A fuel system for a vehicle, comprising:

a fuel vapor canister vent pathway comprising a load conduit coupled to a fuel tank and a vent conduit coupled to atmosphere;

one or more valves coupled within the fuel vapor canister vent pathway;

a fuel vapor canister purge pathway comprising a purge conduit coupled between a fuel vapor canister and an engine intake manifold;

a canister purge valve coupled within the fuel vapor canister purge pathway;

a hydrocarbon sensor coupled within the vent conduit;

an interface configured to receive a refueling request from a vehicle operator and further configured to receive input from the vehicle operator indicating whether limited emission refueling parameters are active; and

a controller configured with instructions stored in non-transitory memory that, when executed, cause the controller to;

depressurize the fuel tank via the fuel vapor canister vent pathway responsive to an indication that the refueling request has been received by the interface;

responsive to an indication that limited emission refueling parameters are active, monitor an output of the hydrocarbon sensor during a refueling event in which a fuel filler neck is accessible; and

flow refueling vapors into the engine intake manifold via the purge conduit responsive to the output of the hydrocarbon sensor increasing above a threshold while maintaining access to the fuel filler neck, the refueling vapors trapped in the engine intake manifold until an engine start-up following the refueling event.

14. The fuel system of claim 13, wherein the hydrocarbon sensor is coupled within the vent conduit between a fresh air port and a canister vent valve, wherein the one or more valves coupled within the fuel vapor canister vent pathway includes the canister vent valve coupled between the fuel vapor canister and atmosphere, and wherein flowing refueling vapors into the engine intake manifold via the purge conduit comprises opening the canister purge valve and duty-cycling the canister vent valve.

15. The fuel system of claim 13, where the controller is further configured with instructions stored in non-transitory memory that, when executed, cause the controller to:

flow the refueling vapors through the fuel vapor canister vent pathway based on the output of the hydrocarbon sensor below the threshold.

16. A method for an evaporative emissions system, comprising:

receiving a request for a refueling event;

receiving an indication that limited emission refueling parameters are active;

venting a fuel tank to atmosphere via a fuel vapor canister;

allowing access to a fuel filler neck responsive to an absolute fuel tank pressure decreasing below a threshold;

monitoring an output of a hydrocarbon sensor coupled between the fuel vapor canister and atmosphere; and

during a first condition where the refueling event is ongoing, responsive to the output of the hydrocarbon sensor increasing above a threshold, maintaining access to the fuel filler neck and reducing a resistance of vapor flow through a fuel vapor canister purge pathway relative to a resistance of vapor flow through a fuel vapor canister vent pathway to trap refueling vapors in an engine intake manifold until an engine start-up.

17. The method of claim 16, further comprising:

during a second condition, responsive to the output of the hydrocarbon sensor increasing above the threshold, restricting vapor flow through both the fuel vapor canister purge pathway and the fuel vapor canister vent pathway.

18. The method of claim 17, wherein the first condition comprises a fuel tank fill level below a threshold, and the second condition comprises the fuel tank fill level above the threshold.

19. The method of claim 17, wherein the first condition follows the second condition, and wherein the first condition further follows a number of trickle-fill attempts greater than a threshold.