Method and system for determining air-fuel imbalance
AssigneeFord Global Technologies, LLC
InventorsDouglas Raymond Martin, Aed M. Dudar, Robert Roy Jentz, John Eric Rollinger
Life of this patent
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Abstract
Methods and systems are provided to determine air-fuel imbalance of cylinders in a variable displacement engine. In one example, the method may include during a cylinder deactivation event, sequentially deactivating each cylinder of a cylinder group including two or more cylinders and estimating a lambda deviation for each cylinder following the sequential deactivation of each cylinder of the cylinder group; and learning an air error for each cylinder based on the estimated lambda deviation.
Claims19
A method for an engine, comprising:
- during a cylinder deactivation event,
- sequentially deactivating each cylinder of a cylinder group including two or more cylinders;
- estimating a lambda deviation for each cylinder following the sequential deactivation of each cylinder of the cylinder group;
- learning an air error for each cylinder based on the estimated lambda deviation;
- and
- indicating an air-fuel ratio imbalance for each cylinder based on the learned air error for said cylinder.
A method for an engine, comprising:
- estimating a first lambda with all cylinders firing;
- selectively deactivating a first cylinder and estimating a second lambda;
- then, reactivating the first cylinder while selectively deactivating a second cylinder and estimating a third lambda;
- learning a first air error for the first cylinder based on the second lambda relative to the first lambda;
- learning a second air error for the second cylinder based on the third lambda relative to the first lambda;
- determining an air-fuel ratio imbalance based on one or more of the learned air errors;
- and
- upon reactivating the first and the second cylinder, adjusting fueling of each of the first and the second cylinder based on each of the first and the second air error to operate the engine at or around stoichiometry.
An engine system, comprising:
- an engine cylinder group including two or more cylinders;
- selectively deactivatable fuel injectors coupled to each cylinder of the cylinder group;
- an exhaust air-fuel ratio sensor receiving exhaust from each cylinder of the cylinder group;
- a controller with computer readable instructions stored on non-transitory memory for:
- sequentially deactivating each cylinder of the cylinder group responsive to cylinder deactivation conditions and learning an air error for each cylinder of the cylinder group based on a first lambda deviation estimated at the exhaust air-fuel ratio sensor following the sequential deactivation;
- sequentially fueling each cylinder of the cylinder group responsive to deceleration fuel shut-off conditions and learning a fuel injector error for each cylinder of the cylinder group based on a second lambda deviation estimated at the exhaust air-fuel ratio sensor following the sequential fueling;
- and
- indicating cylinder air-fuel imbalance based on the learned air error relative to the learned fuel injector error.
Dependencies are inferred from the claim text.