Method and system for fuel system control

Patent metadata

Field	Value
Publication number	US-10161349-B2
Application number	US-201715634907-A
Country	US
Kind code	B2
Filing date	Jun 27, 2017
Priority date	Jun 8, 2015
Publication date	Dec 25, 2018
Grant date	Dec 25, 2018

Abstract

Methods and systems are provided for increasing a lift pump voltage to a high threshold voltage responsive to a DI pump efficiency being below a threshold efficiency, and increasing a lift pump voltage to a first threshold voltage less than the high threshold voltage responsive to a main jet pump fuel reservoir level being less than a first threshold reservoir level. The approach increases fuel jet pump performance and thereby reducing engine stalls induced by fuel vaporization, while maintaining DI pump efficiency and fuel economy.

First claim

The invention claimed is:

1. A method, comprising:
increasing a lift pump voltage to a first threshold voltage responsive to a main jet pump fuel reservoir level being less than a first threshold reservoir level, and
increasing the lift pump voltage to a second threshold voltage responsive to the main jet pump fuel reservoir level being less than a second threshold reservoir level, wherein the second threshold reservoir level is less than the first threshold reservoir level, and wherein the second threshold voltage is greater than the first threshold voltage.

2. The method of claim 1 , further comprising
increasing the lift pump voltage to the first threshold voltage responsive to a fuel tank level being less than the first threshold reservoir level.

3. The method of claim 2 , further comprising
pulsing a lift pump voltage to a high threshold voltage responsive to a DI pump efficiency being below a threshold efficiency; wherein the high threshold voltage is greater than the first threshold voltage and the second threshold voltage.

4. The method of claim 3 , further comprising increasing the lift pump voltage to the second threshold voltage responsive to a lift pump pressure being less than a low threshold pressure for a threshold duration and the fuel tank level being less than a threshold sump level, wherein the threshold sump level is less than the first threshold reservoir level.

5. The method of claim 3 , further comprising increasing the lift pump voltage to the second threshold voltage responsive to the fuel tank level being less than a threshold sump level, wherein the threshold sump level is less than the first threshold reservoir level.

6. The method of claim 5 , further comprising increasing the lift pump voltage to a third threshold voltage responsive to an engine speed being greater than a threshold engine speed wherein the third threshold voltage is greater than the second threshold voltage.

7. The method of claim 5 , further comprising increasing the lift pump voltage to a third threshold voltage responsive to a fuel injection flow rate being greater than a threshold fuel injection flow rate, wherein the third threshold voltage is greater than the second threshold voltage.

8. The method of claim 5 , further comprising increasing the lift pump voltage to a third threshold voltage responsive to a DI pump duty cycle being greater than a threshold duty cycle, wherein the third threshold voltage is greater than the second threshold voltage.

9. The method of claim 5 , further comprising operating a lift pump voltage at a third threshold voltage when an estimated time for a fuel rail pressure to decrease by a threshold pressure drop is greater than a threshold time interval, wherein the third threshold voltage is greater than the second threshold voltage.

10. A method, comprising:
operating a lift pump in a first mode responsive to a fuel tank level decreasing below a first threshold reservoir level, wherein the first mode comprises increasing a lift pump voltage to a first threshold voltage, and
deactivating the first mode and operating the lift pump in a second mode responsive to a main jet pump fuel reservoir level decreasing below a second threshold reservoir level, wherein the second threshold reservoir level is below the first threshold reservoir level, and wherein the second mode comprises increasing the lift pump voltage to a second threshold voltage greater than the first threshold voltage and less than the high threshold voltage.

11. The method of claim 10 , further comprising:
responsive to a DI pump efficiency decreasing below a threshold efficiency, deactivating the first or second mode and pulsing a lift pump voltage to a high threshold voltage greater than the first threshold voltage.

12. The method of claim 11 , further comprising, responsive to the DI pump efficiency decreasing below the threshold efficiency, incrementing the lift pump voltage by a threshold incremental voltage.

13. The method of claim 10 , further comprising:
deactivating the first mode and operating the lift pump in the second mode responsive to the fuel tank level decreasing below a threshold sump level, wherein the threshold sump level is less than the first threshold reservoir level.

14. The method of claim 13 , further comprising deactivating the first or second mode and operating the lift pump in a third mode responsive to a fuel injection flow rate increasing above a threshold flow rate, wherein the third mode comprises increasing the lift pump voltage to a third threshold voltage greater than the second threshold voltage and less than the high threshold voltage.

15. The method of claim 14 , further comprising deactivating the first or second mode and operating the lift pump in a third mode responsive to an engine speed increasing above a threshold engine speed.

16. The method of claim 13 , further comprising deactivating the first or second mode and operating the lift pump in a third mode responsive to a DI pump duty cycle increasing above a threshold DI pump duty cycle.

17. A method, comprising:
responsive to a lift pump pressure below a fuel vaporization pressure, increasing a lift pump pressure to the fuel vaporization pressure;
responsive to a DI pump efficiency decreasing below a threshold efficiency, increasing a lift pump pressure to a high threshold pressure; and
responsive to a main jet pump fuel reservoir level being less than a first threshold reservoir level increasing a lift pump pressure to a first threshold pressure less than the high threshold pressure.

18. The method of claim 17 , further comprising:
responsive to a fuel tank level being less than the first threshold reservoir level, increasing the lift pump pressure to the first threshold pressure.

19. The method of claim 18 , further comprising:
responsive to the main jet pump fuel reservoir level decreasing below a second threshold reservoir level less than the first threshold reservoir level, increasing the lift pump pressure to a second threshold pressure greater than the first threshold pressure.

20. The method of claim 19 , further comprising:
responsive to the fuel tank level being below a threshold fuel tank level less than the threshold reservoir level, increasing the lift pump pressure to the second threshold pressure.

Assignees

• Ford Global Tech Llc

Inventors

• Pursifull Ross Dykstra
• Woodring Christopher Arnold
• Ulrey Joseph Norman
• Ord David

Classifications

• F02D2200/101

  Engine speed · CPC title

• F02D2200/06

  Fuel or fuel supply system parameters · CPC title

• F02D41/3854 Primary

  with elements in the low pressure part, e.g. low pressure pump · CPC title

• F02D41/3082 Primary

  Control of electrical fuel pumps · CPC title

• F02D2200/0614

  Actual fuel mass or fuel injection amount · CPC title