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.
Claims20
A method, comprising:
- injecting fuel from a direct-injector, with a high-pressure pump disabled, to reduce a direct-injection fuel rail pressure below a threshold pressure;
- then, 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-fuel ratio error based on a rise in fuel rail pressure following the selectively opening.
A method for an engine, comprising:
- with a high-pressure fuel pump disabled,
- learning an air component of cylinder torque variation based on a first change in direct-injection fuel rail pressure upon commanding a direct-injector to selectively open a threshold duration before a spark event in a cylinder that is fueled via port-injection only;
- and
- learning a fuel component of the cylinder torque variation based on a second change in direct-injection fuel rail pressure upon commanding the direct-injector to open in a cylinder that is fueled via direct-injection only.
An engine system, comprising:
- an engine including a cylinder;
- a port-injector coupled to the cylinder;
- a direct-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 first threshold pressure, and then disabling the direct-injector;
- transiently opening the direct-injector during a compression stroke, but before a spark event of the cylinder, without delivering any fuel;
- 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.
A method, comprising:
- injecting fuel from a direct-injector, with a high-pressure pump disabled, to reduce a direct-injection fuel rail pressure below a threshold pressure;
- then, 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, wherein the threshold pressure is a function of barometric pressure, and the threshold duration is based on engine speed and load.
Dependencies are inferred from the claim text.