Method and system for engine control
AssigneeFord Global Technologies, LLC
InventorsMichael Uhrich, Imtiaz Ali, Mario Anthony Santillo, Joseph Thomas
Life of this patent
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Abstract
Methods and systems are provided for improving fuel efficiency, monitor completion, and tailpipe emissions of a variable displacement engine. Fueling is initially disabled in cylinders selected to be deactivated while pumping air through the cylinders to an exhaust after-treatment catalyst and oxygen sensor. Once the sensor shows a lean response and catalyst monitoring is completed, cylinder valve operation is also disabled to reduce pumping losses and prevent further oxygen saturation of exhaust components.
Claims20
A method comprising:
- responsive to decreased torque demand,
- deactivating fuel to a cylinder, while maintaining valve operation;
- and
- further deactivating the valve operation of the cylinder responsive to completion of an exhaust catalyst and/or associated exhaust oxygen sensor diagnostic.
A method for an engine with selectively deactivatable cylinders, comprising:
- responsive to vehicle deceleration,
- disabling fuel to selected engine cylinders from stoichiometric or rich operation while continuing to pump air through cylinder valves towards a downstream exhaust catalyst and exhaust gas oxygen sensor;
- and
- disabling intake and exhaust valves of the selected engine cylinders only after a lean response at the exhaust gas oxygen sensor.
An engine system, comprising:
- a cylinder of an engine;
- a selectively deactivatable fuel injector coupled to the cylinder;
- a selectively deactivatable valve mechanism coupled to an intake valve and an exhaust valve of the cylinder;
- another cylinder of the engine;
- an exhaust after-treatment device coupled downstream of the cylinder and the another cylinder, the after-treatment device including a first, upstream catalyst and a second, downstream catalyst;
- a UEGO sensor coupled upstream of the first catalyst;
- a HEGO sensor coupled in between the first catalyst and the second catalyst;
- and
- a controller with computer readable instructions stored on non-transitory memory that when executed cause the controller to:
- responsive to decreased operator torque demand,
- operate the cylinder in a deceleration fuel shut-off mode with fuel disabled and valve operation enabled while maintaining the another cylinder active;
- monitor a change in air-fuel ratio at the first catalyst via an output of the HEGO sensor while flowing air, without fuel, through the cylinder to the exhaust after-treatment device;
- and
- responsive to the monitored change being indicative of oxygen saturation of the first catalyst, transition the cylinder to a deceleration cylinder cut-off mode with fuel and valve operation disabled.
Dependencies are inferred from the claim text.