Volumetric Efficiency Based Lift Pump Control

• US 20090090331A1
• Filed: 10/04/2007
• Published: 04/09/2009
• Est. Priority Date: 10/04/2007
• Status: Abandoned Application

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Pursifull, Ross Dykstra
• Application Number:
  US11/867,552
• Publication Number:
  US 20090090331A1
• Time in Patent Office: Days
• US Class Current: 123/446
• CPC Class Codes: F02M 37/0058 Returnless fuel systems, i.e. the fuel return lines are not entering the fuel tank

Abstract

As one example, a method of operating a fuel delivery system of a directly injected internal combustion engine including a plurality of in-cylinder direct fuel injectors, a higher pressure fuel pump and a lower pressure fuel pump is provided. The method comprises operating the lower pressure fuel pump and the higher pressure fuel pump to maintain a prescribed fuel pressure at the fuel injectors; and varying an amount of pump work that is provided by the lower pressure fuel pump relative to the higher pressure fuel pump responsive to an indication of the efficiency of the higher pressure pump.

Claims

1. A method of operating a fuel delivery system of a directly injected internal combustion engine including a plurality of in-cylinder direct fuel injectors, a higher pressure fuel pump and a lower pressure fuel pump, the method comprising:

operating the lower pressure fuel pump and the higher pressure fuel pump to maintain a prescribed fuel pressure at the fuel injectors; and

varying an amount of pump work that is provided by the lower pressure fuel pump relative to the higher pressure fuel pump responsive to an indication of the efficiency of the higher pressure pump.

2. The method of claim 1, wherein the amount of pump work provided by the higher pressure pump is varied by adjusting a volume of fuel provided by each pump stroke and the amount of pump work provided by the lower pressure pump is varied by adjusting an amount of electrical power supplied to the lower pressure pump.

3. The method of claim 2, wherein the lower pressure pump is powered by an electric motor and the higher pressure pump is powered by the engine.

4. The method of claim 1, wherein the efficiency of the higher pressure pump includes a volumetric efficiency.

5. The method of claim 4, wherein the indication of volumetric efficiency is based on at least a volumetric flow rate of fuel through the higher pressure fuel pump and a pressure increase across the higher pressure fuel pump.

6. The method of claim 1, wherein the indication of efficiency is based on at least a speed of the higher pressure pump, a volume of each pump stroke of the higher pressure pump, a change in a fuel pressure provided by the higher pressure pump, and a rate at which fuel is injected into the engine by the fuel injectors.

7. An engine system, comprising:

an internal combustion engine including at least one combustion chamber;

a direct in-cylinder fuel injector configured to inject fuel directly into the combustion chamber;

a fuel system configured to deliver pressurized fuel to the injector via a lower pressure fuel pump and a higher pressure fuel pump;

a control system configured to operate the lower pressure fuel pump and the higher pressure fuel pump to provide pressurized fuel to the direct in-cylinder injector and adjust an operating parameter of the lower pressure fuel pump responsive to an indication of efficiency of the higher pressure fuel pump.

8. The system of claim 7, wherein the operating parameter includes an amount of electrical energy provided to the lower pressure fuel pump.

9. The system of claim 7, wherein the operating parameter includes a pressure increase across the lower pressure fuel pump.

10. The system of claim 7, wherein the operating parameter includes a level of pump work provided by the lower pressure fuel pump.

11. The system of claim 7, wherein the higher pressure fuel pump and the lower pressure fuel pump are arranged in series and wherein the higher pressure fuel pump is operated by being mechanically driven by the engine and the lower pressure fuel pump is operated by being driven by an electric motor.

12. The system of claim 7, wherein the control system is further configured to adjust an operating parameter of the higher pressure fuel pump to maintain a prescribed fuel pressure at the injector and wherein the control system is configured to adjust the operating parameter of the higher pressure pump by varying a timing of a command signal provided to a valve of the higher pressure pump.

13. The system of claim 12, wherein the control system is further configured to adjust the operating parameter of the lower pressure fuel pump to maintain the prescribed fuel pressure at the injector and wherein the control system is configured to adjust the operating parameter of the lower pressure fuel pump by varying a level of electrical power provided to a motor of the lower pressure fuel pump.

14. The system of claim 13, wherein the control system is further configured to adjust the operating parameter of the higher pressure fuel pump responsive to more rapid deviations of a pressure of the pressurized fuel from the prescribed pressure;

and to adjust the operating parameter of the lower pressure fuel pump responsive to less rapid deviations of the pressure of the pressurized fuel from the prescribed pressure.

15. The system of claim 7, wherein the control system is configured to adjust the operating parameter of the lower pressure fuel pump to maintain the indication of the higher pressure fuel pump efficiency above a prescribed efficiency.

16. The system of claim 15, wherein the efficiency is a volumetric efficiency.

17. The system of claim 7, wherein the control system is further configured to vary a relative amount of pump work provided by each of the lower pressure fuel pump and the higher pressure fuel pump responsive to the indication of efficiency of the higher pressure fuel pump and an indication of fuel pressure within the fuel system between the higher pressure fuel system and the injector.

18. The system of claim 17, wherein the indication of fuel pressure in the fuel system is obtained by the control system from a fuel pressure sensor and wherein the indication of efficiency of the higher pressure fuel pump is based on a speed of the higher pressure pump, a stroke volume of the higher pressure pump, a change in the indication of fuel pressure, and a total volume of fuel injected into the engine.

19. A fuel delivery system for a directly injected internal combustion engine, comprising:

a fuel storage tank;

a fuel rail;

a fuel delivery passage coupling the fuel the fuel storage tank with the fuel rail;

an electrically driven lower pressure fuel pump arranged along the fuel delivery passage between the fuel storage tank and fuel rail;

a mechanically driven higher pressure fuel pump arranged along the fuel delivery passage between the lower pressure fuel pump and the fuel rail;

at least one direct in-cylinder injector communicating with the fuel rail; and

a control system configured to;

operate the lower pressure fuel pump to provide a first fuel pressure increase within the fuel delivery passage across the lower pressure fuel pump;

operate the higher pressure fuel pump to provide a second fuel pressure increase within the fuel delivery passage across the higher pressure fuel pump, greater than the first fuel pressure increase; and

adjust the first fuel pressure increase provided across the lower pressure fuel pump in response to a volume of fuel flowing through the higher pressure fuel pump and the second fuel pressure increase provided by the higher pressure fuel pump.

20. The system of claim 19, wherein the control system is configured to adjust the first fuel pressure increase provided across the lower pressure fuel pump by varying an amount of electrical power provided to the lower pressure fuel pump and wherein the higher pressure fuel pump is mechanically driven by the engine.