Fuel vapor enrichment for exhaust exothermic catalyst light-off

• US 20050132697A1
• Filed: 12/18/2003
• Published: 06/23/2005
• Est. Priority Date: 12/18/2003
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Ament, Frank, Furness, Mary Beth
• Granted Patent: US 8,464,518 B2
• Time in Patent Office: Days
• US Class Current: 60/289
• CPC Class Codes: F01N 3/32 using air pump using jet air pumps F01N3/34; pumps in general F04
• CPC Class Codes: F02D 41/0032 Controlling the purging of the canister as a function of the engine operating conditions
• CPC Class Codes: F02D 41/0045 Estimating, calculating or determining the purging rate, amount, flow or concentration
• CPC Class Codes: F02D 41/064 at cold start F02D41/067 takes precedence
• CPC Class Codes: F02M 25/089 Layout of the fuel vapour installation
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

An engine system includes an engine with a secondary air source, a fuel system that communicates with the engine, and a controller that communicates with the fuel system. The controller controls a first quantity of liquid fuel to the engine at a first A/F ratio and a second quantity of vapor fuel to the engine at a second A/F ratio. The liquid and vapor fuel mixture has a third A/F ratio. A secondary air source provides additional air to the third A/F ratio. The controller determines an available A/F ratio of vapor fuel within the fuel tank and performs a comparison with a target A/F ratio range. The second quantity is set to zero if the A/F ratio of the vapor fuel is outside of the target A/F ratio range. The controller adjusts the first and second quantities based on a comparison between an exhaust A/F ratio and a target exhaust A/F ratio.

Claims

1. An engine system including an engine and a fuel system that communicates with the engine, comprising:

a controller that communicates with the fuel system and that controls a first quantity of liquid fuel to the engine at a first A/F ratio and a second quantity of vapor fuel to the engine at a second A/F ratio to provide a fuel mixture having a third A/F ratio; and

a secondary air source that supplies air to increase said third A/F ratio released from the engine.

2. The engine system of claim 1 wherein said first A/F ratio is lower than a stoichiometric A/F ratio.

3. The engine system of claim 1 wherein said controller adjusts said first and second quantities based on whether the secondary air source is operational.

4. The engine system of claim 1 wherein said controller controls an initial A/F ratio of liquid fuel supplied to the engine and estimates said third A/F ratio based thereon.

5. The engine system of claim 1 wherein said controller determines an available A/F ratio of vapor fuel within said fuel tank, performs a comparison with a target A/F ratio range, and wherein said second quantity is set to zero if said A/F ratio of said vapor fuel is outside of said target A/F ratio range.

6. The engine system of claim 4 wherein said controller adjusts said available A/F ratio based on an A/F ratio offset.

7. The engine system of claim 1 wherein said controller receives an exhaust A/F ratio from an exhaust A/F ratio sensor, compares said exhaust A/F ratio to a target A/F ratio range, and adjusts said first and second quantities if said exhaust A/F ratio is outside of said target A/F ratio range.

8. The engine system of claim 6 wherein said controller calculates an A/F ratio offset based on said exhaust A/F ratio and said target A/F ratio.

9. A method of operating a combustion engine with a secondary air source, comprising:

supplying liquid fuel having a first A/F ratio to the engine;

supplying liquid fuel at a second A/F ratio and vapor fuel at a third A/F ratio to the engine that produces an exhaust A/F ratio while the secondary air source is operational.

10. The method of claim 9 wherein said second A/F is less than a stochiometric A/F ratio.

11. The method of claim 9 further comprising calculating said third A/F ratio based on said first A/F ratio.

12. The method of claim 9 further comprising:

determining an available A/F ratio of vapor fuel within a fuel tank; and

comparing said available A/F ratio with a target A/F ratio range, wherein said third mass is zero if said available A/F ratio is outside of said target A/F ratio range.

13. The method of claim 12 further comprising adjusting said available A/F ratio based on an A/F ratio offset.

14. The method of claim 9 further comprising controlling a valve in communication with a supply of vapor fuel to regulate said vapor fuel.

15. The method of claim 9 further comprising:

comparing an exhaust A/F ratio to a target A/F ratio; and

adjusting flow of said liquid fuel and said vapor fuel if said exhaust A/F ratio is not equal to said target A/F ratio.

16. The method of claim 15 further comprising:

determining an A/F ratio offset based on said exhaust A/F ratio and said target A/F ratio;

storing said A/F ratio offset; and

adjusting said third A/F ratio based on said A/F ratio offset.

17. A method of operating a combustion engine with a secondary air source comprising:

determining a first A/F ratio of a first supply of liquid fuel;

determining a second A/F ratio of a second supply of vapor fuel based on said first A/F ratio;

supplying said first supply of liquid fuel and said second supply of vapor fuel to the engine; and

supplying air to exhaust gas from the engine while the secondary air source is operational.

18. The method of claim 17 wherein said first A/F ratio is less than a stoichiometric A/F ratio.

19. The method of claim 17 further comprising:

determining a third A/F ratio of a third supply of liquid fuel supplied to said engine during starting; and

calculating said second A/F ratio based on said third A/F ratio.

20. The method of claim 17 further comprising:

determining an available A/F ratio of vapor fuel within a fuel tank; and

comparing said available A/F ratio with a target A/F ratio range, wherein said second supply is zero if said available A/F ratio is outside of said target A/F ratio range.

21. The method of claim 20 further comprising adjusting said available A/F ratio based on an A/F ratio offset.

22. The method of claim 17 further comprising controlling a valve in communication with a supply of vapor fuel to regulate said second supply of vapor fuel.

23. The method of claim 17 further comprising:

comparing an exhaust A/F ratio to a target A/F ratio; and

adjusting said first supply and second supply if said exhaust A/F ratio is not equal to said target A/F ratio.

24. The method of claim 23 further comprising:

determining an A/F ratio offset based on said exhaust A/F ratio and said target A/F ratio;

storing said A/F ratio offset; and

adjusting said third A/F ratio based on said A/F ratio offset.