Methods and systems for adjusting a direct fuel injector

• US 9,689,342 B2
• Filed: 12/01/2014
• Issued: 06/27/2017
• Est. Priority Date: 12/01/2014
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Ranga, Adithya Pravarun Re, Meinhart, Mark, Zhang, Hao, Surnilla, Gopichandra, Thomas, Joseph Lyle
• Primary Examiner(s): SOLIS, ERICK R
• Application Number:
  US14/556,674
• Publication Number:
  US 20160153391A1
• Time in Patent Office: 939 Days
• Field of Search: 123299, 7311445, 7311448
• CPC Class Codes: F02B 3/12 Methods of operating
• CPC Class Codes: F02D 2041/389 for injecting directly into the cylinder
• CPC Class Codes: F02D 41/08 for idling F02D41/06, F02D41/16 take precedence
• CPC Class Codes: F02D 41/1454 the characteristics being an oxygen content or concentration or the air-fuel ratio
• CPC Class Codes: F02D 41/2438 Active learning methods
• CPC Class Codes: F02D 41/2467 for injectors
• CPC Class Codes: F02D 41/26 using computer, e.g. microprocessor
• CPC Class Codes: F02D 41/401 Controlling injection timing F02D41/402 takes precedence
• CPC Class Codes: F02D 41/402 Multiple injections
• CPC Class Codes: F02M 65/001 Measuring fuel delivery of a fuel injector
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

Systems and methods for improving fuel injection of an engine that includes a cylinder receiving fuel from a direct fuel injector are disclosed. In one example, a transfer function or gain of a direct fuel injector is adjusted in response to an exhaust lambda value and a first pulse width of two pulse widths provided to an injector of a cylinder during a cylinder cycle.

Claims

1. A method for a cylinder comprising:

during a learning condition,

delivering a first pulse width and a second pulse width to a fuel injector supplying fuel to the cylinder during a cylinder cycle;

varying a ratio of the first pulse width to the second pulse width by decreasing the first pulse width while increasing the second pulse width; and

determining an injector transfer function based on the ratio and an engine lambda value; and

adjusting a control parameter of the injector based on the transfer function.

2. The method of claim 1, wherein the control parameter of the fuel injector is a fuel injector gain, and wherein varying the ratio includes decreasing the first pulse width while increasing the second pulse width by a predetermined amount in a stepwise manner during the learning condition.

3. The method of claim 2, wherein varying the ratio further includes decreasing the first pulse width while increasing the second pulse width until the first pulse width decreases to a minimum pulse width, and further comprising, in response to the first pulse width decreasing to the minimum pulse width, eliminating the second pulse width and operating the fuel injector with a single fuel injection.

4. The method of claim 3, wherein the second pulse width is greater than the first pulse width, and wherein the first pulse width is supplied to the injector for delivering a first fuel injection, and the second pulse width is supplied to the injector for delivering a second fuel injection.

5. The method of claim 4, wherein the first pulse width operates the injector in a ballistic region where flow through the injector is non-linear, and wherein the second pulse width operates the injector in a non-ballistic region.

6. The method of claim 5, wherein the fuel injector is a direct fuel injector, and wherein the first and the second pulse widths are based on obtaining a stoichiometric engine lambda value of one.

7. The method of claim 4, wherein the first fuel injection is delivered prior to the second fuel injection during an intake stroke of the cylinder cycle, and wherein the first and the second fuel injections are separated by a minimum crank angle degree.

8. The method of claim 1, wherein the cylinder is in an engine and, wherein during the learning condition, the engine is operated at a constant speed and air mass.

9. The method of claim 4, wherein the first and the second fuel injections are performed at constant rail pressure during the learning condition.

10. The method of claim 1, further comprising, during the learning condition, varying a fuel injector rail pressure, and at each rail pressure, varying the ratio of the first pulse width to the second pulse width, measuring the engine lambda value for each ratio, and determining a direct fuel injector variability transfer function based on the rail pressure, the ratio and the engine lambda value.

11. A method for operating a fuel injector fueling a cylinder in an engine, comprising:

during a first condition when the engine is operating at a constant speed and air mass,

splitting a desired fuel injection amount into a first fuel fraction and a second fuel fraction;

operating the fuel injector at a first pulse width to deliver the first fuel fraction at a first injection timing; and

operating the fuel injector at a second pulse width to deliver the second fuel fraction at a second injection timing later than the first injection timing during a cylinder cycle; and

during subsequent cylinder cycles occurring after the cylinder cycle, decreasing a ratio of the first pulse width to the second pulse width by a predetermined amount while maintaining the desired fuel injection amount;

measuring an engine lambda value during each cylinder cycle; and

learning a fuel injector transfer function based on the lambda value and the ratio;

wherein decreasing the ratio includes decreasing the first pulse width while increasing the second pulse width.

12. The method of claim 11, further comprising, during a second condition, adjusting a control parameter of the fuel injector based on the learnt transfer function;

and wherein the second condition is based on one or more of a current engine speed, current engine load, and current torque demand.

13. The method of claim 12, further comprising, operating the fuel injector at a constant rail pressure during the first condition.

14. The method of claim 13, wherein the desired fuel injection amount is based on providing a cylinder air-to-fuel ratio to obtain an engine lambda value of one.

15. The method of claim 11, wherein the fuel injector is a direct fuel injector, and wherein the first pulse width and the second pulse width are delivered during an intake stroke of the cylinder cycle.

16. The method of claim 15, wherein the ratio is decreased stepwise by the predetermined amount until the first pulse width is decreased to a minimum pulse width.

17. The method of claim 11, wherein the first pulse width operates the fuel injector in a non-linear ballistic region, and the second pulse width operates the fuel injector in a non-ballistic region;

and wherein the first pulse width and the second pulse width are separated by a crank angle degree.

18. A method for a cylinder including a direct fuel injector, comprising:

during a learning condition,

delivering a nominal fuel injection without split-ratio and a split-ratio fuel injection;

varying the split-ratio by decreasing a first fuel injection fraction of the split-ratio fuel injection while increasing a second fuel injection fraction of the split-ratio fuel injection until the first fuel injection fraction is decreased to a minimum amount; and

comparing a first UEGO output of the nominal fuel injection without split-ratio and a second UEGO output of the split-ratio fuel injection to determine a transfer function correction factor for the fuel injector in the cylinder; and

adjusting a fuel injector parameter based on the determined correction factor;

wherein the fuel injector parameter is a fuel injector transfer function.

19. The method of claim 18, wherein the first fuel injection fraction is delivered prior to the second fuel injection fraction during an intake stroke of a cylinder cycle, and is separated by a minimum crank angle degree, and wherein during the learning condition, an engine including the cylinder is operated with constant air mass and speed.

20. The method of claim 19, wherein the direct fuel injector operates in a ballistic region to deliver the first fuel injection fraction, and wherein the direct fuel injector operates in a non-ballistic region to deliver the second fuel injection fraction.