Methods and system for determining engine air-fuel ratio imbalance

Patent metadata

Field	Value
Publication number	US-2020191082-A1
Application number	US-201816218399-A
Country	US
Kind code	A1
Filing date	Dec 12, 2018
Priority date	Dec 12, 2018
Publication date	Jun 18, 2020
Grant date	—

Abstract

Systems and methods for operating an engine that includes an oxygen sensor and one or more fuel injectors for each engine cylinder are described. In one example, lines describing a relationship between a fuel mass multiplier and a coefficient of a function describing output of an oxygen sensor to a step change in fuel mass are a basis for determining air-fuel imbalance of engine cylinders.

First claim

1 . An engine operating method, comprising:
adjusting an amount of fuel supplied to a cylinder via a controller according to a cylinder lambda deviation generated via a line describing a relationship between a fuel mass multiplier and a coefficient of a function describing output of an oxygen sensor to a step change in fuel mass.

2 . The method of claim 1 , where the function includes a time constant.

3 . The method of claim 1 , further comprising determining an equation of the line from a point that lies on the line.

4 . The method of claim 3 , where a slope of the line is a predetermined value stored in controller memory.

5 . The method of claim 3 , where the relationship is described via a two dimensional plot, and where one axis of the two dimensional plot represents values of the fuel mass multiplier.

6 . The method of claim 5 , where the cylinder lambda deviation is determined from a value at a point where the line intersects with the one axis.

7 . The method of claim 1 , further comprising determining the coefficient via adjusting a mass of fuel supplied to the cylinder.

8 . An engine operating method, comprising:
adjusting an amount of fuel supplied to a cylinder via a controller according to a slope of a line describing a relationship between a fuel mass multiplier and a coefficient of a function describing output of an oxygen sensor to a step change in fuel mass.

9 . The method of claim 8 , further comprising adjusting spark timing of the cylinder according to the line describing the relationship between the fuel mass multiplier and the coefficient of friction describing output of the oxygen sensor to the step change in fuel mass.

10 . The method of claim 8 , further comprising determining an equation of the line from a point that lies on the line.

11 . The method of claim 10 , where the slope of the line is a predetermined value stored in controller memory.

12 . The method of claim 8 , further comprising determining the relationship via adjusting a value of the fuel mass multiplier.

13 . The method of claim 12 , where the function describes a first order response of the oxygen sensor to the step change in fuel mass.

14 . The method of claim 8 , further comprising determining a point on the line via operating an engine within a predetermined speed and load range.

15 . A system, comprising:
an engine including an oxygen sensor and a plurality of cylinders; and a controller including executable instructions stored in non-transitory memory to determine equation of a line describing a relationship between a fuel mass multiplier and a first coefficient of a function describing output of an oxygen sensor to a step change in fuel mass.

16 . The system of claim 15 , where the equation of the line is determined from a slope of a line stored in controller memory and a second coefficient of the function describing output of the oxygen sensor to the step change in fuel mass delivered to an engine cylinder.

17 . The system of claim 15 , further comprising adjusting an amount of fuel supplied to a cylinder according to a cylinder lambda deviation that is based on the equation of the line.

18 . The system of claim 17 , where the relationship is described via a two dimensional plot, and where one axis of the two dimensional plot represents values of the fuel mass multiplier.

19 . The system of claim 15 , where the air-fuel deviation is determined from a value at a point where the line intersects with the one axis.

20 . The system of claim 15 , further comprising additional instructions to adjust spark timing of the engine responsive to a location along the line where the engine and oxygen sensor are operating.

Assignees

• Ford Global Tech Llc

Inventors

• Kluzner Michael
• Jentz Robert
• Behr Kenneth John
• Weber Christopher
• Bagnasco Andrew

Classifications

• Y02T10/40

  Engine management systems · CPC title

• F02D37/02

  one of the functions being ignition · CPC title

• F02D41/0085 Primary

  Balancing of cylinder outputs, e.g. speed, torque or air-fuel ratio · CPC title

• F02D41/30

  Controlling fuel injection {(F02D41/182, F02D41/24 take precedence)} · CPC title

• F02P5/1512

  with particular means concerning an individual cylinder · CPC title