Method and system for cylinder imbalance estimation
AssigneeFord Global Technologies, LLC
InventorsJoseph Lyle Thomas, Ethan D. Sanborn, Paul Hollar, Daniel Dusa
Life of this patent
Estimating the term…
Abstract
Methods and systems are provided for learning a cylinder-to-cylinder air variation. During conditions when a PFDI engine is operated in a port-injection only mode, prior to port fuel injection, a direct-injection fuel rail pressure may be lowered via direct-injection. Then, prior to a spark event in a port-injected cylinder, the direct-injector may be transiently opened to use the rail pressure sensor for estimating a cylinder compression pressure, and inferring cylinder air charge therefrom.
Claims22
A method, comprising:
- injecting fuel from a direct injector, with output of a high-pressure pump reduced, to lower direct injection fuel rail pressure below a threshold pressure;
- then, port injecting fuel into a cylinder and commanding the direct injector to selectively open a threshold duration before a spark event in the cylinder, without injecting any fuel from the direct injector;
- and
- learning a cylinder air-charge estimate based on a rise in the fuel rail pressure.
A method for an engine, comprising:
- injecting fuel from a direct injector, with a high-pressure pump disabled, to lower direct injection fuel rail pressure below a threshold pressure;
- then, injecting fuel into a cylinder from a port injector on an intake stroke of the cylinder and commanding the direct injector to selectively open on a compression stroke of the cylinder, before a spark event in the cylinder;
- and
- learning an air-fuel ratio error for the cylinder based on a sensed rise in the fuel rail pressure.
An engine system, comprising:
- an engine including a cylinder;
- each of a port fuel injector and a direct fuel injector coupled to the cylinder;
- a high pressure fuel pump delivering fuel to the direct injector via a direct injection fuel rail;
- a pressure sensor for estimating a direct injection fuel rail pressure;
- and
- a controller with computer readable instructions stored on non-transitory memory for:
- operating the direct injector with the fuel pump disabled until the fuel rail pressure falls below a threshold pressure, and then disabling the direct injector, wherein below the first threshold pressure, operating the direct injector results in no fuel flowing out of the direct injector;
- while port fueling the cylinder, transiently opening the direct injector before a spark event of the cylinder, without delivering any fuel via the direct injector, a timing and duration of opening the direct injector based on engine speed;
- estimating cylinder air-charge based on a change in fuel rail pressure during the transient opening;
- and
- adjusting subsequent cylinder fueling based on the estimated cylinder air-charge.
Dependencies are inferred from the claim text.