Lean engine control with multiple catalysts
AssigneeFord Global Technologies, LLC
InventorsIlya V Kolmanovsky, Jing Sun
Life of this patent
Estimating the term…
Abstract
A method for controlling an engine having multiple banks with separate catalysts is described. In particular, coordinate lean and rich operation between the banks is utilized. However, termination of rich operation may be different between the banks to prevent breakthrough of rich exhaust gasses due to lack of stored oxidants. In this situation, the bank that terminated rich operation is operated near stoichiometric. This minimizes breakthrough of emissions, while at the same time minimizing a torque imbalance between the cylinder banks. In particular, the torque imbalance can be further minimized by retarding ignition timing on the rich bank while the other operates near stoichiometry.
Claims21
A method for controlling an engine having a first and second group of cylinders, the first group coupled to a first catalyst and the second group coupled to a second catalyst, comprising:
- concurrently operating the first and second cylinder groups rich of stoichiometry;
- in response to a first indication that said rich operation of at least one of the first and second catalysts should be ended, operating the group coupled to the at least one catalyst near stoichiometry while continuing operation of the other group rich of stoichiometry;
- and
- in response to a second indication that said rich operation of the other catalyst should be ended, ending rich operation of the other group.
An article of manufacture, comprising:
- a computer storage medium for controlling an engine having a first and second group of cylinders with a first catalyst coupled the first group exclusive of the second group and a second catalyst coupled to the second group exclusive of the first group, said medium comprising:
- code for concurrently operating the first and second cylinder groups rich of stoichiometry;
- code for providing a first indication that said rich operation of at least one of the first and second catalysts should be ended;
- and
- code for operating the group coupled to the at least one catalyst near stoichiometry while continuing operation of the other group rich of stoichiometry in response to said first indication.
A method for controlling an engine having a first and second group of cylinders, the first group coupled to a first catalyst and the second group coupled to a second catalyst, comprising:
- concurrently operating the first and second cylinder groups rich of stoichiometry;
- in response to a first indication that at least one of the first and second catalysts has depleted stored oxidants, operating the group coupled to the at least one catalyst near stoichiometry while continuing operation of the other group rich of stoichiometry;
- and
- in response to a second indication that the other catalyst has depleted stored oxidants, ending rich operation of the other group.
Dependencies are inferred from the claim text.