System and method for determining set point location for oxidant-based engine air/fuel control strategy

• US 20050204728A1
• Filed: 05/11/2005
• Published: 09/22/2005
• Est. Priority Date: 06/20/2001
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Motor Company
• Inventors: Hahn, Stephen L., Lewis, Donald James, Bower, Stanley Larue Jr., Carlstrom, Kevin Ronald
• Granted Patent: US 7,076,943 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 13/0097 the purifying devices are arranged in a single housing
• CPC Class Codes: F01N 2430/00 Influencing exhaust purification, e.g. starting of catalytic reaction, filter regeneration, or the like, by controlling engine operating characteristics
• CPC Class Codes: F01N 2430/06 by varying fuel-air ratio, e.g. by enriching fuel-air mixture
• CPC Class Codes: F01N 2550/02 Catalytic activity of catalytic converters
• CPC Class Codes: F01N 2570/16 Oxygen
• CPC Class Codes: F01N 3/0814 combined with catalytic converters, e.g. NOx absorption/storage reduction catalysts
• CPC Class Codes: F01N 3/0842 Nitrogen oxides
• CPC Class Codes: F01N 3/20 specially adapted for catalytic conversion F01N3/22 takes precedence; Methods of operation or control of catalytic converters
• CPC Class Codes: F02D 2200/0404 Throttle position
• CPC Class Codes: F02D 2200/0802 Temperature of the exhaust gas treatment apparatus
• CPC Class Codes: F02D 2200/0814 Oxygen storage amount
• CPC Class Codes: F02D 2200/0816 Oxygen storage capacity
• CPC Class Codes: F02D 2200/501 Vehicle speed
• 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: F02D 41/0295 Control according to the amount of oxygen that is stored on the exhaust gas treating apparatus
• CPC Class Codes: F02D 41/062 for starting F02D41/061 takes precedence
• CPC Class Codes: F02D 41/126 transitional corrections at the end of the cut-off period
• CPC Class Codes: F02D 41/1441 Plural sensors
• CPC Class Codes: F02D 41/1446 : the characteristics being exhaust temperatures
• CPC Class Codes: F02D 41/1479 : Using a comparator with variable reference
• CPC Class Codes: F02D 41/1487 : Correcting the instantaneous control value
• CPC Class Codes: F02D 41/187 : using a hot wire flow sensor
• CPC Class Codes: F02D 41/2422 : Selective use of one or more tables
• CPC Class Codes: F02M 25/08 : adding fuel vapours drawn from engine fuel reservoir electrical control of purge system F02D41/003
• CPC Class Codes: F02P 5/1502 : using one central computing unit
• 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. An available oxidant storage capacity of the catalyst is determined by establishing an oxidant set point location, i.e., a location in the catalyst about which the system controls the oxidant storage. The oxidant set point is established based on the temperatures of the different potential set point locations and the levels of deterioration of the different potential set point locations, as well as the oxidant storage capacity of the emission control device system.

Claims

1-26. -26. (canceled)

27. A method for controlling an engine coupled to an emission control device, the method comprising:

determining a set-point location inside said emission control device;

moving said set-point location along the length of the device based on an operating condition;

determining a set-point amount of oxidant stored in the device at said moved location and modulating said set-point amount;

calculating an actual amount of oxygen stored in the device; and

adjusting a fuel injection amount based at least on both said modulated set-point amount and said actual amount of oxidant.

28. The method recited in claim 27 wherein said set point amount is determined based on said moved location.

29. The method recited in claim 27 wherein said actual amount of oxidant stored is based on an engine shutdown condition.

30. The method recited in claim 27 further comprising suspending said fuel injection adjustment based on said moved location during specified conditions.

31. The method recited in claim 27 wherein said actual amount of oxidant is determined for each brick in said emission control device.

32. The method recited in claim 27 further comprising feedback from an air-fuel ratio sensor used to update said determination of actual amount of oxidant stored.

33. The method recited in claim 27 wherein said emission control device includes multiple catalysts.

34. The method recited in claim 27 wherein said emission control device includes multiple bricks in a catalyst.

35. The method recited in claim 32 wherein said feedback includes updating said actual amount of oxidants stored based on said sensor wherein said sensor is located downstream of said emission control device.

36. The method recited in claim 27 wherein said set-point is moved within a brick in a catalyst within the emission control device.

37. The method recited in claim 27 wherein said set-point is moved based on at least a first and second temperature of different bricks within said emission control device.

38. The method recited in claim 27 wherein said set-point is moved based on the determination of differences in deterioration in different bricks in the emission control device.

39. The method recited in claim 27 wherein said adjusting said fuel injection maintains at least some reserve oxidant storage capacity behind said moved location.