Systems and methods for reducing bleed emissions

• US 9,651,002 B2
• Filed: 09/24/2014
• Issued: 05/16/2017
• Est. Priority Date: 09/24/2014
• 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.
• Primary Examiner(s): SOLIS, ERICK R
• Application Number:
  US14/495,796
• Publication Number:
  US 20160084175A1
• Time in Patent Office: 965 Days
• Field of Search: 123518-520, 7311439
• CPC Class Codes: B60K 15/03504 adapted to avoid loss of fuel or fuel vapour, e.g. with vapour recovery systems
• CPC Class Codes: B60K 15/03519 Valve arrangements in the vent line
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/15 Control strategies specially adapted for achieving a particular effect
• CPC Class Codes: F02D 41/0032 Controlling the purging of the canister as a function of the engine operating conditions
• CPC Class Codes: F02D 41/0035 to achieve a special effect, e.g. to warm up the catalyst
• CPC Class Codes: F02D 41/0045 Estimating, calculating or determining the purging rate, amount, flow or concentration
• CPC Class Codes: F02D 41/042 for stopping the engine
• CPC Class Codes: F02M 25/0809 Judging failure of purge control system
• 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: F02M 25/0854 Details of the absorption canister
• CPC Class Codes: F02M 25/089 Layout of the fuel vapour installation

Abstract

A method for a fuel system, comprising: during a first condition, including an engine-off condition and a sealed fuel tank, directing fresh air into a fuel vapor canister responsive to detecting hydrocarbons in a canister vent line. By directing fresh air into the fuel vapor canister, fuel vapor stored within the canister may be redistributed away from the canister vent line. In this way bleed emissions from the fuel system may be reduced without the need for a dedicated bleed canister.

Claims

1. A method for a fuel system, comprising:

during a first condition, including an engine-off condition and a sealed fuel tank, directing fresh air into a fuel vapor canister responsive to detecting hydrocarbons in a canister vent line.

2. The method of claim 1, wherein directing fresh air into the fuel vapor canister comprises:

directing fresh air into a vent port coupling the fuel vapor canister to the canister vent line.

3. The method of claim 2, wherein directing fresh air into the fuel vapor canister further comprises:

activating a vacuum pump coupled within the canister vent line.

4. The method of claim 3, where the vacuum pump is coupled within an evaporative leak check module.

5. The method of claim 4, where the vacuum pump is operable in a first direction to direct fresh air into the fuel vapor canister and further operable in a second direction to draw a vacuum on the fuel vapor canister.

6. The method of claim 3, further comprising:

adjusting a conformation of a vent valve coupled between the fuel vapor canister and a vent line inlet and adjusting a conformation of a reversing valve coupled between a fuel vapor canister buffer and an engine intake.

7. The method of claim 6, further comprising:

opening a canister purge valve coupled between the fuel vapor canister buffer and the engine intake; and

drawing fresh air through the canister purge valve and into the vent port.

8. The method of claim 7, further comprising:

deactivating the vacuum pump responsive to detecting hydrocarbons in the canister vent line.

9. The method of claim 1, where detecting hydrocarbons in the canister vent line comprises:

following a vehicle-off event, sleeping a controller;

waking the controller after a pre-determined duration; and

measuring a hydrocarbon concentration in the canister vent line with a hydrocarbon sensor.

10. The method of claim 1, where detecting hydrocarbons in the canister vent line comprises:

following a vehicle-off event, sleeping a controller while maintaining a hydrocarbon sensor coupled within the canister vent line on, the hydrocarbon sensor communicatively coupled to a wake input of the controller; and

waking the controller responsive to a hydrocarbon sensor output increasing above a threshold.

11. A fuel system, comprising:

a fuel vapor canister;

an air pump coupled between a vent port of the fuel vapor canister and atmosphere;

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

redistribute fuel vapor within the fuel vapor canister away from the vent port by activating the air pump; and

a fuel tank isolation valve coupled between the fuel vapor canister and a fuel tank, wherein the controller is further configured with instructions stored in non-transitory memory, that when executed, cause the controller to;

maintain the fuel tank isolation valve closed while redistributing fuel vapor within the fuel vapor canister away from the vent port.

12. The fuel system of claim 11, wherein the air pump is coupled within an evaporative leak check module coupled within a vent line coupled between the vent port and atmosphere, the air pump configured to draw a vacuum on the fuel vapor canister.

13. The fuel system of claim 12, wherein the air pump is operable in a first direction to draw a vacuum on the fuel vapor canister and further operable in a second direction to direct fresh air into the fuel vapor canister.

14. The fuel system of claim 12, further comprising:

a reversing valve coupled between a fuel vapor canister buffer and a purge line, the reversing valve operable between a first conformation and a second conformation and configured to;

couple the fuel vapor canister buffer to the purge line when in the first conformation; and

couple the fuel vapor canister buffer to the air pump when in the second conformation; and

a canister vent valve coupled between the fuel vapor canister and the vent line, the canister vent valve operable between a first conformation and a second conformation and configured to;

couple the fuel vapor canister to the air pump when in the first conformation;

couple the reversing valve to the air pump when in the second conformation; and

couple the vent port to the purge line when in the second conformation.

15. The fuel system of claim 14, further comprising:

a hydrocarbon sensor coupled within the vent line;

a purge valve coupled within the purge line; and

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

responsive to a hydrocarbon sensor output increasing above a threshold, open the purge valve;

place the canister vent valve in the second conformation;

place the reversing valve in the second conformation; and

activate the air pump.

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

responsive to the hydrocarbon sensor output increasing above the threshold, close the purge valve;

place the canister vent valve in the first conformation;

place the reversing valve in the first conformation; and

activate the air pump.

17. The fuel system of claim 15, where the hydrocarbon sensor is communicatively coupled to a wake input of the controller, and wherein the controller is further configured with instructions stored in non-transitory memory, that when executed, cause the controller to:

sleep following a vehicle-off event; and

wake responsive to the hydrocarbon sensor output increasing above the threshold.

18. A method for a vehicle, comprising:

responsive to a vehicle-off event, setting a hydrocarbon breakthrough detection strategy;

responsive to a hydrocarbon sensor output increasing above a threshold, opening a canister purge valve coupled within a canister purge line;

coupling a canister vent port to the canister purge line;

coupling a canister purge port to a vacuum pump;

maintaining a fuel tank isolation valve closed; and

activating the vacuum pump.

19. The method of claim 18, where setting the hydrocarbon breakthrough detection strategy includes:

sleeping a controller following the vehicle-off event;

maintaining awake a hydrocarbon sensor coupled to a wake input of the controller; and

waking the controller responsive to the wake input indicating that the hydrocarbon sensor output increased above the threshold.