METHODS AND SYSTEMS FOR A FUEL SYSTEM

• US 20140230794A1
• Filed: 02/21/2013
• Published: 08/21/2014
• Est. Priority Date: 02/21/2013
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Surnilla, Gopichandra, Basmaji, Joseph F., Pursifull, Ross Dykstra
• Granted Patent: US 9,453,466 B2
• Time in Patent Office: Days
• US Class Current: 123/495
• CPC Class Codes: F02D 19/0605 to adjust the fuel pressure or temperature
• CPC Class Codes: F02D 2200/0606 Fuel temperature
• CPC Class Codes: F02D 2250/02 Fuel evaporation in fuel rails, e.g. in common rails
• CPC Class Codes: F02D 41/3082 Control of electrical fuel pumps
• CPC Class Codes: F02D 41/3854 with elements in the low pressure part, e.g. low pressure pump
• CPC Class Codes: F02M 37/0058 Returnless fuel systems, i.e. the fuel return lines are not entering the fuel tank
• CPC Class Codes: F02M 37/04 Feeding by means of driven pumps
• CPC Class Codes: F02M 37/08 electrically driven

Abstract

Various methods and system are described for a fuel system which includes a fuel composition sensor and a fuel lift pump disposed upstream of the sensor. The system may be operated in each of three different modes of operation. In each of the modes, a fuel lift pump voltage is adjusted responsive to a fuel capacitance output by the sensor, while a variable such as sensor temperature or fuel pump pressure is maintained depending on the mode of operation.

Claims

1. A method for a gasoline direct injection engine system, comprising:

operating a fuel lift pump at a pressure within a threshold range above a fuel vapor pressure, the vapor pressure based on fuel capacitance.

2. The method of claim 1, wherein the fuel capacitance is measured via a fuel composition sensor.

3. The method of claim 1, wherein the fuel capacitance is measured via a higher pressure pump, the higher pressure pump operating at a higher pressure than the fuel lift pump and disposed downstream of the fuel lift pump along a fuel passage.

4. The method of claim 1, further comprising, responsive to the fuel capacitance exceeding a threshold capacitance, adjusting the fuel lift pump pressure.

5. The method of claim 1, further comprising, in a second mode, maintaining a temperature at a predetermined temperature at a location where the fuel capacitance is obtained, and adjusting the fuel lift pump pressure responsive to an indication of fuel vaporization.

6. The method of claim 1, further comprising, in a third mode, responsive to an indication of fuel vaporization, increasing the fuel lift pump pressure or reducing a fuel temperature.

7. A method for a fuel system including a fuel composition sensor and a fuel lift pump, comprising:

in a first mode, maintaining a fuel lift pump pressure at a selected pressure above a fuel vapor pressure, and adjusting a fuel lift pump voltage responsive to a fuel capacitance;

in a second mode, maintaining a temperature of the sensor at a selected temperature, and adjusting the fuel lift pump pressure responsive to an indication of fuel vaporization, the indication responsive to a fuel vapor pressure which is based on the fuel capacitance; and

in a third mode, increasing the fuel lift pump pressure responsive to the indication of fuel vaporization.

8. The method of claim 7, wherein the fuel composition sensor is disposed in a fuel passage downstream of the fuel lift pump and upstream of a higher pressure pump which operates at a higher pressure than the fuel lift pump.

9. The method of claim 7, wherein the fuel composition sensor is a higher pressure pump which operates at a higher pressure than the fuel lift pump, the higher pressure pump disposed downstream of the fuel lift pump along a fuel passage.

10. The method of claim 7, further comprising, in the third mode, reducing a fuel temperature responsive to the indication of fuel vaporization.

11. The method of claim 7, wherein the fuel lift pump voltage in the first mode is adjusted independent of the fuel lift pump pressure in the second mode.

12. The method of claim 7, wherein the fuel lift pump voltage in the first mode is adjusted independent of the fuel lift pump voltage in the third mode.

13. The method of claim 7, further comprising, operating the fuel system in only one of the first, second, or third modes at one time.

14. The method of claim 7, wherein the fuel composition sensor is part of a gasoline direct injection engine system.

15. A fuel system, comprising:

a fuel lift pump;

a fuel composition sensor positioned downstream of the fuel lift pump in a fuel passage, and configured to output a signal indicating fuel capacitance;

a control system in communication with the sensor, the control system including non-transitory instructions to adjust a fuel lift pump voltage responsive to the fuel capacitance in each of three different modes of operation.

16. The fuel system of claim 15, wherein the control system further includes instructions to maintain a fuel lift pump pressure at a selected pressure above a fuel vapor pressure, the fuel vapor pressure based on the fuel capacitance in a first mode of operation.

17. The fuel system of claim 15, wherein the control system further includes instructions to maintain a temperature of the sensor at a selected temperature, and wherein the fuel lift pump voltage is adjusted responsive to an indication of fuel vaporization in a second mode of operation.

18. The fuel system of claim 15, wherein the control system further includes instructions to increase a fuel lift pump pressure responsive to an indication of fuel vaporization in a third mode of sensor operation.

19. The fuel system of claim 15, further comprising a higher pressure pump positioned downstream of the fuel lift pump, the higher pressure pump configured to operate at a higher pressure than the fuel lift pump, and wherein the higher pressure pump is the sensor.

20. The fuel system of claim 15, wherein the fuel system is part of a gasoline direct injection engine system.