VARIABLE RESTRICTION FUEL VAPOR CANISTER

• US 20140096750A1
• Filed: 10/05/2012
• Published: 04/10/2014
• Est. Priority Date: 10/05/2012
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Pearce, Russell Randall
• Granted Patent: US 9,518,538 B2
• Time in Patent Office: Days
• US Class Current: 123/520
• CPC Class Codes: F02M 25/0818 having means for pressurising the evaporative emission space
• CPC Class Codes: F02M 25/0854 Details of the absorption canister
• CPC Class Codes: F02M 25/089 Layout of the fuel vapour installation

Abstract

Systems and methods for operating an engine with a fuel vapor recovery system are disclosed. In one example approach, a method for an engine with a fuel vapor recovery system comprises increasing an amount of flow restriction between storage material in a fuel vapor canister while maintaining a vent valve open during a fuel vapor purging event.

Claims

1. A method for an engine with a fuel vapor recovery system, comprising:

increasing an amount of flow restriction between storage material in a fuel vapor canister while maintaining a vent valve open during a fuel vapor purging event.

2. The method of claim 1, wherein increasing an amount of flow restriction is performed in response to an amount of fuel purged from the canister less than a threshold.

3. The method of claim 1, further comprising decreasing an amount of flow restriction between storage material in the fuel vapor canister following the fuel vapor purging event.

4. The method of claim 1, further comprising increasing an amount of vacuum provided to the fuel vapor canister before increasing an amount of flow restriction between storage material in the fuel vapor canister.

5. The method of claim 4, wherein increasing an amount vacuum provided to the fuel vapor canister is performed in response to an amount of fuel purged from the canister less than a threshold.

6. The method of claim 1, wherein the fuel vapor canister includes a first charcoal bed in communication with a second charcoal bed and wherein increasing an amount of flow restriction includes restricting communication between the first and second charcoal beds.

7. The method of claim 1, wherein increasing an amount of flow restriction between storage material in the fuel vapor canister includes increasing an amount of flow restriction between storage material in the fuel vapor canister by a first amount in response to a first event and increasing an amount of flow restriction between storage material in the fuel vapor canister by a second amount in response to a second event, where the second event is subsequent to the first event and where the second amount is greater than the first amount.

8. The method of claim 7, wherein the first event is an initiation of the fuel vapor purge event and the second event is an amount of fuel purged from the canister less than a threshold.

9. The method of claim 7, wherein the first event is an amount of fuel purged from the canister less than a first threshold and the second event is an amount of fuel purged from the canister less than a second threshold.

10. A method for an engine with a fuel vapor recovery system, comprising:

initiating a fuel vapor purging event;

restricting flow restriction between storage material in a fuel vapor canister by a first amount;

in response to an amount of fuel vapor purged from the fuel vapor canister below a first threshold, restricting flow restriction between storage material in the fuel vapor canister by a second amount, where the second amount is greater than the first amount; and

in response to an amount of fuel vapor purged from the fuel vapor canister below a second threshold, restricting flow restriction between storage material in the fuel vapor canister by a third amount, where the third amount is less than the second amount.

11. The method of claim 10, wherein initiating a fuel vapor purging event includes opening a vent valve coupled to the fuel vapor canister and maintaining the vent valve open at a fixed position throughout a duration of the fuel vapor purging event.

12. The method of claim 10, wherein the third amount of restriction is substantially the same as the first amount of restriction and flow restriction between storage material in the fuel vapor canister is maintained at the first amount following the fuel vapor purging event.

13. The method of claim 10, further comprising increasing an amount of vacuum provided to the fuel vapor canister before restricting flow restriction between storage material in the fuel vapor canister by the second amount.

14. The method of claim 13, wherein increasing an amount of vacuum provided to the fuel vapor canister is performed in response to an amount of fuel vapor purged from the fuel vapor canister below a third threshold.

15. The method of claim 10, wherein the fuel vapor canister includes a first charcoal bed in communication with a second charcoal bed and wherein restricting flow restriction between storage material in the fuel vapor canister includes restricting communication between the first and second charcoal beds.

16. A system for an engine with a fuel vapor recovery system, comprising:

a fuel vapor canister;

a restriction valve disposed in a purge flow path between storage material in the fuel vapor canister;

an atmosphere vent coupled to the fuel vapor canister and a vent valve disposed therein;

a purge conduit coupled to the fuel vapor canister and an intake of the engine

a controller configured to;

adjust the restriction valve to increase an amount of flow restriction between storage material in the fuel vapor canister during a fuel vapor purging event while maintaining the vent valve open at a fixed position during the fuel vapor purging event.

17. The system of claim 16, wherein the controller is further configured to open the vent valve to the fixed position in response to an initiation of a fuel vapor purging event and close the vent valve following the fuel vapor purging event.

18. The system of claim 16, wherein the controller is further configured to adjust a purge valve in the purge conduit or increase a duty-cycle of a pump in the purge conduit before adjusting the restriction valve to increase an amount of vacuum provided to the fuel vapor canister during a fuel vapor purging event, wherein the purge valve is adjusted or the duty-cycle of the pump is increased in response to an amount of fuel purged from the fuel vapor canister less than a threshold.

19. The system of claim 16, wherein the controller is further configured to adjust the restriction valve to increase an amount of flow restriction between storage material in the fuel vapor canister in response to an amount of fuel purged from the canister less than a threshold.

20. The system of claim 16, where the controller is further configured to adjust the restriction valve to decrease an amount of flow restriction between storage material in the fuel vapor canister following a fuel vapor purging event.