Method of diagnosing injector variability in a multiple injector system

Patent metadata

Field	Value
Publication number	US-9593637-B2
Application number	US-201314098363-A
Country	US
Kind code	B2
Filing date	Dec 5, 2013
Priority date	Dec 5, 2013
Publication date	Mar 14, 2017
Grant date	Mar 14, 2017

Abstract

Various systems and methods are described for diagnosing injector variability in a dual fuel, multi-injector system. In one example, a single injector in one cylinder is enabled while remaining cylinders are fueled with a first fuel and subsequently, a second fuel is injected via the enabled injector into the one cylinder in a predetermined sequence and fuel rail pressure drops are measured. Further, measured pressure drop after each injection event is corrected for an increase in injector closing delay.

First claim

The invention claimed is:

1. A method for controlling fuel injection of a multi-injector-per-cylinder engine including first and second rails, comprising:
when only a single injector-per-cylinder is determined by a controller to be enabled:
injecting a first fuel to all but a single cylinder of the engine;
injecting, via an injector, a second fuel into the single cylinder; and
indicating injector degradation in response to a magnitude of pressure drop in the second rail and a determined correction for closing delay of the injector.

2. The method of claim 1 , further comprising:
before injecting the second fuel:
raising fuel rail pressure of the second rail; and
suspending pump operation of a fuel pump coupled only to the second rail;
wherein the determined correction for the closing delay of the injector includes a percentage increase in delay at each rail pressure drop compared to a base fuel rail pressure.

3. The method of claim 2 , wherein the correction for the closing delay increases with decreasing fuel rail pressure.

4. The method of claim 1 , wherein the engine includes a port fuel injector and a direct fuel injector for each engine cylinder.

5. The method of claim 4 , wherein the second fuel is injected into the single cylinder through a direct injector while the remaining cylinders are fueled with the first fuel via port injectors.

6. The method of claim 3 , wherein the degradation is further based upon a pressure drop corrected for pressure and bulk modulus, wherein the correction increases as actual bulk modulus decreases.

7. A method for controlling fuel injection of a multi-injector, dual fuel engine which includes first and second fuel rails, comprising:
when dual-fuel operation is not needed:
performing a calibration event including:
injecting a first fuel via port injectors to all but one cylinder of the engine; and
while pumping is suspended in the second fuel rail, injecting a second fuel via a direct injector into the one remaining cylinder; and

if the calibration event is performed long enough to cause a decline in rail pressure from a first level to a second level, then correlating magnitudes of pressure drops corrected for an injector closing delay to injector degradation.

8. The method of claim 7 , further comprising:
before suspending pump operation coupled to the second fuel rail:
increasing pressure in the second fuel rail to a preset level;
wherein, the injector closing delay correction increases with a decrease in fuel rail pressure.

9. The method of claim 8 , wherein an increase in closing delay of an injector is measured as a percentage increase from closing delay at a base fuel rail pressure.

10. The method of claim 7 , further comprising:
correcting fuel rail pressure drop at each injection event for pressure and bulk modulus, and adjusting subsequent fuel injection based on the corrected fuel rail pressure drop.

11. The method of claim 7 , wherein fuel injection of the second fuel in the one cylinder is adjusted based on the corrected pressure drops once pumping of the second fuel is resumed by a second pump.

12. The method of claim 7 , wherein the first fuel is gasoline and the second fuel is ethanol.

13. A system for an engine in a vehicle, comprising:
a plurality of cylinders, each cylinder having a first and a second injector where the first injector is coupled to a first fuel rail and the second injector is coupled to a second fuel rail; and
a control system comprising a computer readable storage medium, the medium comprising instructions for:
during a first condition, injecting fuel to all cylinders via the first injectors; and
during a second condition when both fuels are not needed:
injecting fuel to all but one cylinder via the first injectors;
operating a high pressure pump coupled to the second injectors to elevate fuel rail pressure to a predetermined level;
suspending pumping of fuel into the second fuel rail while continuing pumping of fuel into the first fuel rail;
injecting fuel to the one cylinder via only the second injector; and
indicating injector degradation based on a magnitude of fuel rail pressure drop corrected for closing delay.

14. The system of claim 13 , wherein the first injectors inject a first fuel and the second injectors inject a second fuel.

15. The system of claim 13 , wherein the first injectors are configured as port injectors and the second injectors are configured as direct injectors.

16. The system of claim 13 , wherein the first condition includes operating conditions in which only one fuel is used and a diagnostic routine is not being carried out.

17. The system of claim 14 , wherein the second condition includes operating conditions in which both fuels are used and a diagnostic routine is being carried out.

18. The system of claim 13 , further comprising instructions for, during a third condition, injecting all cylinders via the first and second injectors.

19. The system of claim 13 , wherein the fuel rail pressure drop is corrected by an amount based on an increase in injector closing delay calculated as a percentage change in closing delay at each rail pressure compared to a base rail pressure.

20. The system of claim 19 , wherein a closing delay correction of an injector increases as fuel rail pressure decreases.

Assignees

• Ford Global Tech Llc

Inventors

• Surnilla Gopichandra
• Ranga Adithya Pravarun Re
• Meinhart Mark

Classifications

• Y02T10/30

  Use of alternative fuels, e.g. biofuels · CPC title

• F02D2200/0618

  Actual fuel injection timing or delay, e.g. determined from fuel pressure drop · CPC title

• F02D13/0207

  changing valve lift or valve lift and timing · CPC title

• Y02T10/40

  Engine management systems · CPC title

• F02D41/3094 Primary

  the fuel injection being effected by at least two different injectors, e.g. one in the intake manifold and one in the cylinder · CPC title