System and method for controlling catalyst storage capacity

• US 20040200210A1
• Filed: 04/28/2004
• Published: 10/14/2004
• Est. Priority Date: 06/20/2001
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Hahn, Stephen L., Lewis, Donald James, Bower, Stanley Larue Jr., Carlstrom, Kevin Ronald
• Granted Patent: US 7,007,461 B2
• Time in Patent Office: Days
• US Class Current: 60/285
• CPC Class Codes: F01N 11/007 the diagnostic devices measuring oxygen or air concentration downstream of the exhaust apparatus
• CPC Class Codes: F01N 2550/02 Catalytic activity of catalytic converters
• CPC Class Codes: F01N 2570/16 Oxygen
• CPC Class Codes: F01N 3/0842 Nitrogen oxides
• CPC Class Codes: F02D 2200/0814 Oxygen storage amount
• CPC Class Codes: F02D 2200/0816 Oxygen storage capacity
• CPC Class Codes: F02D 37/02 one of the functions being ignition
• CPC Class Codes: F02D 41/0275 the exhaust gas treating apparatus being a NOx trap or adsorbent
• CPC Class Codes: F02P 5/151 with means for compensating the variation of the characteristics of the engine or of a sensor, e.g. by ageing
• CPC Class Codes: F02P 5/1514 with means for optimising the use of registers or of memories, e.g. interpolation
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

The invention relates to a new method and system for optimizing the efficiency of an automotive catalytic converter by adjusting the engine air/fuel ratio based on estimates of the actual amount of oxidants stored in the catalyst. The oxidant storage capacity of the catalyst is adjusted by controlling engine spark in response to an estimate of a current amount of oxidants stored in the catalyst and an estimate of the total available oxidant storage capacity of the catalyst. To maintain engine speed in spite of adjustments to the engine spark, the engine air mass is also adjusted.

Claims

1-14. -14. (cancelled)

15. A method for controlling operating of an engine having at least a catalyst, the method comprising:

estimating an amount of oxygen stored in at least a portion of a catalyst;

during a first set of conditions, adjusting fuel injected based on said estimate of said amount of oxygen stored in the catalyst; and

during a second set of conditions that include returning from a fuel shut-off condition, providing a rich air/fuel operation to reduce NOx emissions.

16. The method of claim 15 wherein during said first set of conditions, fuel injected is adjusted based on said estimate of oxygen storage amount in catalyst and a desired oxygen storage amount.

17. The method of claim 15 wherein said estimate is based on catalyst deterioration.

18. The method of claim 17 wherein said injected fuel is based on a difference between said estimate and a set-point amount of oxygen.

19. The method of claim 18 wherein said set-point amount of oxygen is an amount of oxygen before a set-point location along the length of the catalyst.

20. The method of claim 19 wherein said set-point location along the length of the catalyst is adjusted based on catalyst deterioration.

21. A method for controlling operating of an engine having at least a catalyst, the method comprising:

estimating an amount of oxygen stored in at least a portion of a catalyst;

during a first set of conditions, adjusting fuel injected based on said estimate of said amount of oxygen stored in the catalyst;

during a high catalyst temperature conditions, providing a rich air/fuel operation; and

upon returning from said high catalyst temperature conditions, providing a lean air/fuel operation to re-oxidize the catalyst and lower hydrocarbon emissions.

22. The method of claim 21 wherein during said first set of conditions, fuel injected is adjusted based on said estimate of oxygen storage amount in catalyst and a desired oxygen storage amount.

23. A method for controlling operating of an engine having at least a catalyst, the method comprising:

estimating an amount of oxygen stored in at least a portion of a catalyst;

during a first set of conditions, adjusting fuel injected based on said estimate of said amount of oxygen stored in the catalyst;

during a second set of conditions that include returning from a fuel shut-off condition, providing a rich air/fuel operation to reduce NOx emissions;

during a high catalyst temperature conditions, providing a rich air/fuel operation; and

upon returning from said high catalyst temperature conditions, providing a lean air/fuel operation to re-oxidize the catalyst and lower hydrocarbon emissions.

24. The method of claim 23 wherein during said first set of conditions, fuel injected is adjusted based on said estimate of oxygen storage amount in catalyst and a desired oxygen storage amount.

25. The method of claim 23 wherein said estimate is based on catalyst deterioration.

26. The method of claim 25 wherein said injected fuel is based on a difference between said estimate and a set-point amount of oxygen.

27. The method of claim 26 wherein said set-point amount of oxygen is an amount of oxygen before a set-point location along the length of the catalyst.

28. The method of claim 27 wherein said set-point location along the length of the catalyst is adjusted based on catalyst deterioration.