Methods and system for engine control

Patent metadata

Field	Value
Publication number	US-10018143-B2
Application number	US-201615242050-A
Country	US
Kind code	B2
Filing date	Aug 19, 2016
Priority date	Aug 19, 2016
Publication date	Jul 10, 2018
Grant date	Jul 10, 2018

Abstract

Systems and methods for determining air-fuel error in an engine fueled via direct and port fuel injection. Errors associated with individual fuel injection systems are distinguished from a common error based on trends in the error correction coefficients of the individual fuel injection systems. Adaptive fuel multipliers for each injection system are updated to account for the common error.

First claim

The invention claimed is:

1. A method for fueling a cylinder, comprising:
injecting fuel to the cylinder via a first fuel injector and a second fuel injector; and distinguishing, by processing an exhaust sensor and determining an error associated with the first fuel injector or the second fuel injector from a common fuel system error as a function of a rate of change of air-fuel ratio error and a fraction of fuel injected via the first fuel injector or the second fuel injector, including learning at least a portion of the air-fuel ratio error as the common fuel system error based on whether a first ratio of the rate of change of air-fuel ratio error to the fraction of fuel injected via the first fuel injector is within a threshold of a second ratio of the rate of change of air-fuel ratio error to the fraction of fuel injected via the second fuel injector and whether each of the first ratio and the second ratio is higher than a threshold value.

2. The method of claim 1 , wherein the common fuel system error includes one or more of an airflow error associated with an airflow path delivering air to both the first fuel injector and the second fuel injector, and a fuel-type error associated with the fuel injected by both the first fuel injector and the second fuel injector.

3. The method of claim 1 , wherein the distinguishing further includes: if the first ratio is not within the threshold difference of the second ratio, learning the air-fuel ratio error as the error associated with the first fuel injector when the first ratio is higher than the threshold value; and learning the air-fuel ratio error as the error associated with the second fuel injector when the second ratio is higher than the threshold value.

4. The method of claim 3 , further comprising: adjusting a transfer function of the first fuel injector responsive to learning the air-fuel ratio error as the error associated with the first fuel injector; adjusting a transfer function of the second fuel injector responsive to learning the air-fuel ratio error as the error associated with the second fuel injector; and adjusting the transfer function of each of the first fuel injector and the second fuel injector responsive to learning the air-fuel ratio error as the common fuel system error.

5. The method of claim 3 , further comprising: in response to the error associated with the first fuel injector being higher than a threshold error, fueling an engine via the second fuel injector only; in response to the error associated with the second fuel injector being higher than a threshold error, fueling the engine via the first fuel injector only; and in response to the common error, maintaining fueling of the engine via both the first and second fuel injectors.

6. The method of claim 3 , further comprising comparing the error associated with the first fuel injector to the error associated with the second fuel injector; and based on the comparison, deactivating one of the first and second fuel injectors having a larger error and fueling the engine with a remaining one of the first and second fuel injectors having a smaller error.

7. The method of claim 1 , wherein learning at least a portion of the air-fuel ratio error as the common fuel system error includes learning a first portion of the air-fuel ratio error as the common fuel system error and a second, remaining portion of the air-fuel ratio error as the error associated with the first fuel injector or the second fuel injector, wherein the first portion is based on a minimum of the first ratio and the second ratio.

8. The method of claim 1 , wherein the injecting is performed in each of a plurality of engine air mass flow regions and wherein the error associated with the first fuel injector or the second fuel injector and the common fuel system error is learned in each of the plurality of engine air mass flow regions as a function of air mass flow.

9. The method of claim 1 , where the first fuel injector is a direct fuel injector and where the second fuel injector is a port fuel injector.

10. A method for an engine fuel system, comprising: injecting fuel to an engine cylinder via a first fuel injector and a second fuel injector during a cylinder cycle, the first and second fuel injectors having distinct types of fuel injection; selectively assigning, by processing an exhaust sensor and determining an air-fuel error from the cylinder during the cylinder cycle to a common error associated with the fuel system based on each of a first fuel fraction provided by the first fuel injector, a second fuel fraction provided by the second fuel injector, and the air-fuel error, wherein the selectively assigning includes: learning a first rate of change in the air-fuel error with a change in the first fuel fraction; learning a second rate of change in the air-fuel error with a change in the second fuel fraction; and if the first rate is within a threshold difference of the second rate, and each of the first rate and the second rate is higher than a threshold, assigning the air-fuel error to the common error.

11. The method of claim 10 , wherein the selectively assigning further includes: if the first rate is outside the threshold difference of the second rate while the first and second rates are higher than the threshold, assigning a first portion of the air-fuel error to the first fuel injector, the first portion based on the first fuel fraction provided by the first fuel injector; and assigning a second portion of the air-fuel error to the second fuel injector, the second portion based on the second fuel fraction provided by the second fuel injector.

12. The method of claim 11 , where the selectively assigning the air-fuel error further includes assigning an adapted fuel multiplier corresponding to the common error to each of the first fuel injector and the second fuel injector.

13. The method of claim 12 , wherein the adapted fuel multiplier corresponding to the common error is a first multiplier that is distinct from a second multiplier corresponding to the first portion of the air-fuel error that is assigned to only the first fuel injector, and is also distinct from a third multiplier corresponding to the second portion of the air-fuel error that is assigned to only the second fuel injector.

14. The method of claim 11 , further comprising limiting operation of the first fuel injector or the second fuel injector in response to a greater of the first portion and the second portion of the air-fuel error.

15. An engine system, comprising: an engine including a cylinder; a port fuel injector in fluidic communication with the cylinder; a direct fuel injector in fluidic communication with the cylinder; an exhaust air-fuel ratio sensor; and a controller including executable instructions stored in non-transitory memory to: while operating the engine with closed loop air-fuel ratio control based on feedback from the exhaust air-fuel ratio sensor to provide an air-fuel error, differentiate a determined engine fueling error due to degradation of one or more of the port fuel injector and the direct fuel injector from an engine fueling error determined based on the feedback due to a common error in airflow to both the port and direct fuel injectors based on a ratio of a change in air-fuel error to a change in fuel fraction from the port and direct fuel injectors during engine fueling; and adjust fueling via one or more of the port fuel injector and direct fuel injector responsive to the differentiating, wherein the differentiating includes: indicating degradation of the port fuel injector when the ratio of the change in air-fuel error to the change in fuel fraction fr

Assignees

• Ford Global Tech Llc

Inventors

• Ranga Adithya Pravarun Re
• Surnilla Gopichandra
• Thomas Joseph Lyle
• Sanborn Ethan D
• Linenberg Mark Thomas
• Behr Kenneth John
• Guo Yichao

Classifications

• F02D2200/08

  Exhaust gas treatment apparatus parameters · CPC title

• F02D2041/389

  for injecting directly into the cylinder · CPC title

• F02D41/263

  the program execution being modifiable by physical parameters · CPC title

• F02D41/402 Primary

  Multiple injections · CPC title

• F02D41/1454 Primary

  the characteristics being an oxygen content or concentration or the air-fuel ratio · CPC title