System and method for controlling catalyst storage capacity

• US 20050229588A1
• Filed: 06/17/2005
• Published: 10/20/2005
• 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 7,257,944 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. In an internal combustion engine coupled to an exhaust system having a catalyst, a method of adjusting an oxidant storage capacity of the catalyst, comprising:

estimating a current amount of oxidants stored in the catalyst;

estimating an amount of oxidant storage available in the catalyst;

comparing said estimated amount of oxidants stored in the catalyst to said estimated amount of oxidant storage available;

adjusting an engine operating parameter in response to said comparison to affect a temperature of the catalyst and obtain a desired temperature.

2. The method of claim 1, wherein said engine operating parameter is indicative of engine spark.

3. The method of claim 2, wherein said parameter indicative of engine spark is adjusted based on a temperature of an exhaust flange.

4. The method of claim 2, further comprising the step of adjusting engine air mass in response to said adjusted parameter indicative of engine spark.

5. The method of claim 4, wherein said engine air mass is adjusted based on a parameter indicative of a minimum spark required for best torque.

6-12. -12. (canceled)

13. A system for adjusting an air/fuel ratio in the cylinders of an internal combustion engine coupled to an exhaust system, comprising:

a catalyst positioned in the exhaust stream; and

a controller for estimating an actual amount of oxidants stored in said catalyst, comparing said actual oxidant amount to a target amount of oxidants stored in the catalyst, adjusting an amount of fuel provided to the cylinders based on said comparision, and adjusting an engine operating parameter in response to said comparison to obtain a desired temperature of the catalyst and thereby adjust an oxidant storage capacity of the catalyst.

14. The system of claim 13, wherein said controller adjusts a parameter indicative of engine spark in response to a comparison between said estimate of the actual amount of oxidants stored in the catalyst and an estimate of an available oxidant storage capacity.

15. The system of claim 13, wherein said controller adjusts engine air amount in response to said comparison.

16. In an internal combustion engine coupled to an exhaust system having a catalyst, a method of adjusting an oxidant storage capacity of the catalyst, comprising:

adjusting a fuel injection amount in response to maintain an desired amount of oxidants actually stored in the catalyst relative to the oxidant storage capacity of the catalyst and thereby providing an available oxidant storage; and

adjusting an engine operating parameter other than said fuel injection in response to said available oxidant storage to affect a temperature of the catalyst and obtain a desired temperature, thereby adjusting the oxidant storage capacity of the catalyst.

17. The method of claim 16, wherein said engine operating parameter includes spark angle.

18. The method of claim 16, wherein said engine operating parameter includes engine air mass.

19. In an internal combustion engine coupled to an exhaust system having a catalyst, a method of adjusting an oxidant storage capacity of the catalyst, comprising:

estimating a current amount of oxidants stored in the catalyst;

estimating an amount of oxidant storage available in the catalyst;

comparing said estimated amount of oxidants stored in the catalyst to said estimated amount of oxidant storage available;

adjusting a fuel injection amount in response to said comparison; and

adjusting an engine operating parameter in response to said comparison to obtain a desired temperature of the catalyst and thereby adjust the oxidant storage capacity of the catalyst.

20. The method of claim 19, wherein said engine operating parameter includes engine air mass.