Method and system for purge control

• US 9,970,393 B2
• Filed: 04/01/2015
• Issued: 05/15/2018
• Est. Priority Date: 04/01/2015
• 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., Werner, Matthew
• Primary Examiner(s): Nguyen, Ngoc T
• Application Number:
  US14/676,607
• Publication Number:
  US 20160290285A1
• Time in Patent Office: 1,140 Days
• CPC Class Codes: F01N 5/04 the devices using kinetic energy
• CPC Class Codes: F02B 37/183 Arrangements of bypass valves or actuators therefor
• CPC Class Codes: F02M 2025/0881 with means to heat or cool the canister
• CPC Class Codes: F02M 25/089 Layout of the fuel vapour installation
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

Methods and systems are provided for purging a fuel vapor canister during conditions when purge vacuum is limited, such as during boosted conditions. An exhaust-driven purge pump is used to flow positive pressure air through a canister, and purge the canister to a compressor inlet. The air is heated during the pressurization, improving hydrocarbon desorption from the canister.

Claims

1. A method for an engine, comprising:

during boosted engine operation,

flowing exhaust to an exhaust-driven pump to spin the exhaust-driven pump; and

purging a fuel vapor canister to a compressor inlet with positive pressure drawn from the exhaust-driven pump.

2. The method of claim 1, further comprising, adjusting an output of the exhaust-driven pump via a wastegate.

3. The method of claim 2, wherein the adjusting includes decreasing an opening of the wastegate to increase the output of the exhaust-driven pump.

4. The method of claim 2, wherein an opening of the wastegate is adjusted based on a fuel tank pressure, the opening increased as the fuel tank pressure increases.

5. The method of claim 2, wherein an opening of the wastegate is adjusted based on a temperature of air directed from the exhaust-driven pump into the canister.

6. The method of claim 1, wherein the purging includes closing one or more of a vent valve coupled in a vent line of the canister and a vapor blocking valve coupled between the canister and a fuel tank.

7. The method of claim 6, further comprising, during non-boosted engine operation, while an intake manifold vacuum level is higher than a threshold vacuum, purging the fuel vapor canister to an engine intake, downstream of an intake throttle, with negative pressure drawn from the engine intake;

and while the intake manifold vacuum level is lower than the threshold vacuum, purging the fuel vapor canister to the compressor inlet with positive pressure drawn from the exhaust-driven pump, wherein the threshold vacuum is an intake manifold vacuum level sufficient for purging the fuel vapor canister.

8. A method for an engine, comprising:

during boosted engine operation,

flowing exhaust to an exhaust-driven pump to spin the exhaust-driven pump; and

purging a fuel vapor canister to a compressor inlet with positive pressure drawn from the exhaust-driven pump, wherein the purging includes closing a first purge valve coupled between the canister and an engine intake while opening a second purge valve coupled between the canister and an outlet of the exhaust-driven pump.

9. The method of claim 8, further comprising, adjusting an output of the exhaust-driven pump via a wastegate.

10. The method of claim 9, wherein the adjusting includes decreasing an opening of the wastegate to increase the output of the exhaust-driven pump.

11. The method of claim 9, wherein an opening of the wastegate is adjusted based on a fuel tank pressure, the opening increased as the fuel tank pressure increases.

12. The method of claim 9, wherein an opening of the wastegate is adjusted based on a temperature of air directed from the exhaust-driven pump into the canister.

13. The method of claim 8, wherein the purging further includes closing one or more of a vent valve coupled in a vent line of the canister and a vapor blocking valve coupled between the canister and a fuel tank.

14. The method of claim 13, further comprising, during non-boosted engine operation, while an intake manifold vacuum level is higher than a threshold vacuum, purging the fuel vapor canister to the engine intake, downstream of an intake throttle, with negative pressure drawn from the engine intake;

and while the intake manifold vacuum level is lower than the threshold vacuum, purging the fuel vapor canister to the compressor inlet with positive pressure drawn from the exhaust-driven pump, wherein the threshold vacuum is an intake manifold vacuum level sufficient for purging the fuel vapor canister.

15. The method of claim 14, wherein the purging during non-boosted engine operation includes opening each of the first purge valve and the canister vent valve while closing the second purge valve.